Seal-free self-priming pumps are primarily used for low-level lifting in the wastewater treatment system of the Second Purification Plant, replacing submersible sewage pumps and long-shaft submerged lift pumps in suction tanks. In summary, the use of seal-free self-priming pumps offers simple operation and reduced maintenance workload, making them highly suitable for the wastewater treatment system in natural gas purification plants where safety requirements are critical. Anhui Shengshi Datang now provides an analysis and summary of the usage of seal-free self-priming pumps.

1. Structure and Working Principle of Seal-Free Self-Priming Pumps

(1) Basic Structure of Self-Priming Pumps

Typically, the basic structure of a self-priming pump mainly includes the following components: a liquid storage chamber, a pump body rotor, inlet and outlet valves, a motor, and several other parts that together form the pump.

(2) Basic Working Principle of Seal-Free Self-Priming Pumps

The working principle primarily involves the following processes: first, self-priming and exhaust; second, normal pumping of liquid.

2. Analysis of the Practical Usage of Seal-Free Self-Priming Pumps

(1) Advantages of Seal-Free Self-Priming Pumps in Low-Level Liquid Transport

① Small seal-free self-priming pumps do not require specialized installation foundations or anchor bolts. They can be placed horizontally, making installation simple. They can easily replace existing lift pumps or submersible pumps.

② Easy operation. Normal operation only requires priming the pump once, after which starting and stopping can be done effortlessly.

③ Strong self-priming capability. Within the suction range, they can replace submersible electric pumps, reducing safety hazards.

④ No sealing required. Completely eliminates leakage, dripping, and seepage. During operation, the sealing device does not experience friction, extending its lifespan by more than 10 times. The self-priming performance is stable and reliable, requiring only one initial priming for lifelong self-priming, with superior self-control capability.

⑤ No need for a separate suction device, resulting in a simpler structure and safer operation.

⑥ Maintenance of seal-free self-priming pumps is convenient. These devices rarely malfunction, are easier to maintain compared to other equipment, and do not require significant financial investment.

(2) Specific Analysis of the Technical Performance of Seal-Free Self-Priming Pumps

① Due to the simple structure of self-priming pumps and the use of dynamic combined airflow sealing, the pump's operation does not affect the sealing device. Compared to long bearings, this device is easier to operate and has a lower probability of issues.

② The device primarily relies on the principle of air-water separation, giving it strong self-priming performance. Especially after using an "air control valve," the siphon phenomenon can be maximally disrupted, achieving the effect of lifelong self-priming.

③ The drawback is that it does not have a high work efficiency and consumes more energy.

④ After starting the self-priming pump, it takes some time before water is discharged. Therefore, designers of pump stations must pay attention to this situation, meaning multiple backup pumps should be prepared.

⑤ When a self-priming pump is used to lift wastewater, certain parameters such as flow rate, head, and suction head must be kept within allowable limits. Otherwise, equipment malfunctions may occur, adversely affecting the pump's smooth operation.

⑥ Based on the basic principle of self-priming pumps, it is essential to ensure that the connections at the water pipe interfaces are properly sealed. If the pump experiences insufficient flow, it may fail to operate smoothly.

3. Technological Innovations

(1) Installation of an Air Valve in the Suction Pipeline to Disrupt the Siphon Phenomenon and Retain Sufficient "Priming Liquid" in the Pump Cavity

① In the early stages of using seal-free self-priming pumps, the electric air valves designed by manufacturers were not installed, mainly because they were unsuitable for flammable and explosive environments. Additionally, air valves of this model had many defects, such as frequent malfunctions. Therefore, personnel should use solenoid valves as air valves based on actual application conditions, significantly improving durability and stability.

② Function and Principle of the Electric Air Control Valve

The air valve is typically installed at the high point of the self-priming pump's suction pipe. When the pump starts, the solenoid valve is energized, and the valve core seats downward, ensuring the suction pipeline is sealed to achieve self-priming. When the pump stops, the air valve opens, allowing air to enter the pipe cavity. This separates the liquid in the suction pipe and pump cavity, preventing backflow of the liquid in the pump cavity. This completely disrupts the siphon phenomenon, ensuring the self-priming pump operates normally during the next self-priming cycle. The air valve is particularly suitable for self-priming pumps that start and stop frequently, reducing the need for priming operations.

(2) Use of Steel Wire Flexible Hoses in the Suction Pipe to Facilitate Daily Maintenance and Troubleshooting of Self-Priming Pumps

① Typically, self-priming pumps in wastewater systems, like other pumps, require regular cleaning at specific intervals. If the suction tank is deep, maintaining metal suction pipes requires collaboration among several personnel.

② If the suction pipe of the self-priming pump operates under negative pressure, such as when pinholes occur, insufficient air may reach the pump, preventing normal operation. Moreover, such issues are not easily detectable. By using steel wire flexible hoses, if leakage points occur, the hose can be pulled back to the ground for inspection promptly.

(3) Adjusting the Pump Outlet Diameter to Prevent Motor Overload

① From the perspective of seal-free self-priming pumps, some manufacturers fail to achieve precision during production, resulting in inconsistent power output between the motor and the pump body. This can easily lead to overload situations.

② During specific applications, personnel need to adjust the flow path based on the actual degree of overload to ensure the pump's flow rate remains within allowable limits.

Centrifugal pumps are widely used in industrial production and engineering systems for conveying various liquid media. However, during operation, a phenomenon that severely affects pump performance and service life often occurs—cavitation. Cavitation not only reduces the efficiency of centrifugal pumps but also causes serious damage to key components such as impellers, and can even lead to the complete scrapping of the equipment. Therefore, studying and understanding the causes of cavitation in centrifugal pumps is of great significance for the rational design, correct installation, and safe operation of pumps. Below, Anhui Shengshi Datang will provide you with a detailed introduction.

1. Basic Concept of Cavitation

Cavitation refers to the phenomenon where, as liquid flows through the pump impeller, the local pressure drops below the saturated vapor pressure of the liquid at its operating temperature, causing partial vaporization of the liquid and the formation of numerous tiny vapor bubbles. When these bubbles are carried by the liquid flow into a region of higher pressure, the surrounding pressure rapidly increases, causing the bubbles to collapse instantaneously and condense back into liquid. The collapse of these bubbles generates intense shock waves and localized high temperatures, which impact the impeller surface, leading to fatigue pitting or spalling of the metal. This is the cavitation phenomenon in centrifugal pumps.

The essence of cavitation is the result of the combined action of fluid dynamics and thermodynamics. The fundamental cause is the uneven pressure distribution within the liquid. When the local flow velocity is too high or the geometric design is unreasonable, the local pressure drops, triggering the cyclic process of vaporization and bubble collapse.

2. Root Cause of Cavitation

The root cause of cavitation in centrifugal pumps is that the local pressure of the liquid within the pump falls below the saturated vapor pressure of the liquid at that temperature. In a centrifugal pump, liquid flows from the suction pipe into the impeller inlet. As the flow passage gradually contracts, the liquid velocity increases, and the static pressure consequently decreases. When the local pressure drops to the saturated vapor pressure of the liquid, the liquid begins to vaporize, generating vapor bubbles. These bubbles are carried into the high-pressure region towards the middle and outlet of the impeller, where they rapidly collapse under the high pressure. The high-energy shock waves released during bubble collapse cause metal erosion on the impeller surface, increased pump vibration, enhanced noise, and problems such as reduced flow rate and head.

3. Main Factors Leading to Cavitation

a. Excessive Suction Lift: If the pump is installed too high or the suction liquid level is too low, the pressure on the suction side decreases. As the liquid flows towards the impeller inlet, the pressure drops further. When it falls below the saturated vapor pressure, vaporization occurs. If the suction lift exceeds the allowable NPSH (Net Positive Suction Head), cavitation is inevitable.

b. Excessive Suction Line Resistance: A suction pipeline that is too long, too narrow, has too many elbows, or has a partially closed valve causes significant frictional and local pressure losses. The reduced pressure at the suction end leads to a further pressure drop at the impeller inlet, making cavitation more likely. Additionally, air leakage or poor sealing in the suction piping can introduce gas into the liquid, exacerbating cavitation.

c. Excessively High Liquid Temperature: An increase in liquid temperature significantly raises its saturated vapor pressure, making the liquid more prone to vaporization. For example, the saturated vapor pressure of water is relatively low at room temperature but increases substantially at high temperatures. Even if the suction pressure remains unchanged, the vaporization condition might be met when the temperature rises, thus triggering cavitation.

d. Low Inlet Pressure or Reduced Ambient Pressure: When the pressure at the pump suction source decreases—such as due to a drop in liquid level, a vacuum in the supply container, or low ambient atmospheric pressure (e.g., at high altitudes)—the pressure at the suction port becomes insufficient, making it very easy for the liquid to vaporize at the impeller inlet.

e. Improper Pump Design or Installation: The structural design of the pump directly affects its cavitation performance. For instance, an impeller inlet diameter that is too small, an unreasonable blade leading edge angle, or a rough impeller surface can cause unstable liquid flow, leading to a sharp local pressure drop. Furthermore, failure to follow the manufacturer's provided Required NPSH (NPSHr) requirements during installation, or installing the pump at an excessive height, can also lead to cavitation.

f. Improper Operating Conditions: When the pump operates at flow rates deviating from the design point, runs for extended periods at low flow, or during sudden valve adjustments, the pressure distribution of the fluid changes, which can also cause local vaporization and cavitation.

4. Effects and Hazards of Cavitation

The hazards of cavitation to centrifugal pumps are mainly manifested in the following aspects:

a. Metal Surface Damage: The high-pressure shocks generated by collapsing bubbles cause pitting erosion on the impeller surface. Long-term development can lead to material fatigue, spalling, and even perforation of the impeller.

b. Performance Degradation: Cavitation leads to a significant reduction in flow rate, head, and efficiency, altering the pump's characteristic curves.

c. Vibration and Noise: The impact forces generated by cavitation cause mechanical vibration and high-frequency noise, affecting the stable operation of the equipment.

d. Reduced Service Life: Long-term operation under cavitation conditions accelerates mechanical wear, shortening the service life of bearings, seals, and the impeller.

5. Measures to Prevent Cavitation

To prevent or mitigate cavitation, measures should be taken from the perspectives of design, installation, and operation:

a. Select a reasonable installation height to ensure sufficient pressure on the suction side, making the Available NPSH (NPSHa) greater than the pump's Required NPSH (NPSHr).

b. Optimize the suction pipeline by shortening its length, reducing the number of elbows, increasing the pipe diameter, keeping suction valves fully open, and avoiding air ingress.

c. Control the liquid temperature through cooling or lowering the storage tank temperature to reduce the liquid's saturated vapor pressure.

d. Increase the inlet pressure, for example, by installing a booster pump, pressurizing the liquid surface, or placing the liquid container at a higher elevation.

e. Improve the impeller structure by using materials and geometries with good anti-cavitation properties, such as adding an inducer or optimizing the blade inlet angle.

f. Keep the pump operating near its design point, avoiding prolonged operation at low flow rates or other abnormal operating conditions.

In summary, the occurrence of cavitation in centrifugal pumps is primarily caused by the pressure of the liquid at the impeller inlet being too low, falling below its saturated vapor pressure, which triggers vaporization and subsequent bubble collapse. Specific factors leading to this phenomenon include excessive suction lift, excessive suction resistance, high liquid temperature, low inlet pressure, and improper design or operation. Cavitation not only affects pump performance but also causes severe damage to the equipment. Therefore, in both design and operation, emphasis must be placed on the prevention and control of cavitation. By rationally configuring the system, optimizing structural parameters, and improving operating conditions, the safe and efficient operation of centrifugal pumps can be ensured.

In the structure of a centrifugal pump, the mechanical seal is a core component, directly related to the stable operation and service life of the equipment. The primary function of the mechanical seal is to prevent fluid leakage from the pump, ensuring its normal operation and working efficiency. However, in practical applications, the mechanical seal of centrifugal pumps is often affected by factors such as operating conditions, medium characteristics, and operational maintenance, leading to failures. This results in seal damage, pump leakage, and even equipment shutdown, adversely impacting production safety and environmental protection. Failure of the centrifugal pump mechanical seal not only affects the equipment's performance and safety but also leads to high maintenance costs, increasing production expenses for oilfield enterprises. Therefore, researching the causes and damage mechanisms of mechanical seal failures in centrifugal pumps, and subsequently proposing effective prevention and improvement measures, is of significant importance for reducing the failure rate of mechanical seals and extending their service life. Anhui Shengshi Datang will give you an overview.

1. Analysis of Centrifugal Pump Operating Principle

The operation of a centrifugal pump is based on Bernoulli's equation in fluid dynamics, which states that within a closed system, the energy of a fluid comprises kinetic energy, potential energy, and pressure energy, and these three forms of energy are converted within the pump. The core components of a centrifugal pump are the impeller and the pump casing. When the electric motor drives the pump shaft to rotate, the impeller rotates at high speed, causing the liquid inside the pump to also undergo rotational motion. Under the action of centrifugal force, the liquid is thrown from the center of the impeller towards its periphery, gaining an increase in both kinetic and pressure energy. This change in kinetic and pressure energy causes the liquid to flow out through the pump casing outlet. The pressure at the center of the impeller decreases, forming a low-pressure area, and liquid is continuously drawn into the pump under atmospheric pressure, thus forming a continuous liquid transport process. The operation of a centrifugal pump can be divided into three stages: liquid suction, acceleration, and discharge. In the suction stage, due to the low-pressure zone formed at the impeller center, external liquid flows into the pump under atmospheric pressure. In the acceleration stage, the liquid, acted upon by centrifugal force through the impeller, accelerates towards the pump casing. In the discharge stage, the high-speed liquid is gradually decelerated through the diffuser or volute, converting kinetic energy into pressure energy before being discharged from the pump.

The main components of a centrifugal pump include the impeller, pump casing, pump shaft, mechanical seal, and bearings. The impeller, made of materials like cast iron, stainless steel, or plastic, is the core component. Its design directly determines the pump's flow rate and head. Parameters such as the impeller's shape, size, number of blades, and blade angle significantly affect liquid flow and pressure conversion efficiency. The pump casing, typically volute-shaped, contains the fluid. Its main functions are to collect liquid discharged from the impeller and guide it to the discharge outlet. The casing also facilitates energy conversion by gradually converting the liquid's kinetic energy into pressure energy through diffusion, thereby increasing the pump's head. The pump shaft, driven by the motor and connected to the impeller, transmits mechanical energy from the motor to the impeller, causing it to rotate. The pump shaft must possess high strength and stiffness to withstand centrifugal forces and the reaction forces of the liquid on the impeller. The mechanical seal prevents liquid leakage at the point where the pump shaft and casing interact. Its performance directly affects the pump's efficiency and safety. Bearings support and fix the pump shaft, reducing friction and vibration during rotation, ensuring stable pump operation.

2. Causes of Leakage in Centrifugal Pump Mechanical Seals

(1) Trial Run Leakage.​ The installation precision of the mechanical seal directly affects its sealing effectiveness. If the seal faces are not accurately aligned during installation or if the face gap is set improperly, leakage can occur during trial operation. The stationary and rotating rings should be flat and aligned during installation. Failure to meet this standard can result in poor contact between the sealing faces, creating gaps and allowing medium leakage. Similarly, improper tightening according to design requirements or vibration during installation can cause misalignment of the seal rings, compromising the seal. During the trial run phase, the seal faces may not be fully bedded-in. Under high-speed operation and friction, face wear can lead to leakage. This wear is common if the seal faces have not been pre-treated or run-in, as initial high surface roughness increases frictional heat, exacerbating wear. Face wear reduces the contact integrity of the sealing surfaces, leading to leakage. Additionally, excessively rapid temperature rise during trial runs can cause uneven thermal expansion of the faces, accelerating wear. Vibration generated during pump operation due to bearing wear, imbalance, or other mechanical issues can affect the mechanical seal, which is sensitive to vibration. Vibration causes uneven pressure distribution between the seal faces, potentially leading to misalignment of the rotating and stationary rings, seal failure, and leakage. Particularly during trial runs, excessive axial shaft movement or radial runout beyond standards can adversely affect the stability of the seal components.

(2) Static Test Leakage.​ In mechanical seals, auxiliary sealing elements are typically made of materials like rubber or PTFE. The elasticity and corrosion resistance of these materials significantly impact sealing performance. Improper material selection for auxiliary seals can lead to leakage during static pressure testing. If the seal material lacks corrosion resistance or temperature tolerance, it may deform under static test pressure or temperature, failing to provide an effective seal. Simultaneously, aging, hardening, or loss of elasticity due to temperature changes can prevent the seal faces from fitting tightly, causing leakage. During static testing, pressure within the seal chamber should not fluctuate significantly. Otherwise, uneven pressure on the seal faces may cause leakage. Static tests are usually conducted at slightly higher pressures than operating pressure to verify seal integrity. However, if the pressure is too high or applied unevenly, the seal components can be damaged, compromising the contact between the stationary and rotating rings and causing leakage. Especially during static tests, if the liquid temperature is high, thermal expansion within the seal chamber can cause pressure fluctuations, leading to inadequate sealing. The seal faces, often made of wear-resistant, high-strength materials like silicon carbide or ceramic, are critical. If subjected to excessive pressure during installation or static testing, minor deformation can occur, affecting the faces' ability to mate properly.

(3) Operational Leakage.​ The operating conditions of a centrifugal pump may change with its working state. Variations in fluid temperature, pressure, or flow rate can all affect seal performance. When operating conditions exceed the seal's design limits—such as excessively high temperature or pressure—the material properties of the seal components can degrade, leading to seal failure. Leakage is particularly likely during transient flow fluctuations or under highly variable load conditions. Mechanical seals often rely on the presence of a seal fluid for adequate lubrication and cooling. Insufficient seal fluid flow or excessively high temperature can cause the seal fluid to evaporate or vaporize, reducing sealing effectiveness. Furthermore, impurities or contaminants in the seal fluid can enter the seal chamber, impairing lubrication between the seal faces, accelerating wear, and causing leakage. The material selection and design of the mechanical seal are directly related to its performance. If the seal material has insufficient corrosion resistance, it may corrode when exposed to the pump fluid, leading to decreased sealing performance. Similarly, poor design can cause uneven force distribution on the seal faces or issues related to thermal expansion, resulting in seal failure. Therefore, appropriate material selection and sound design are crucial factors for ensuring the stability of the mechanical seal during normal operation.

(4) Cooling Water Quality.​ The role of cooling water is to ensure temperature control for the mechanical seal, preventing seal failure due to high temperatures. If the cooling water quality does not meet standards, it can lead to mechanical seal leakage. If the cooling water contains impurities, solid particles, oil contamination, or other pollutants, it can negatively impact the working environment of the mechanical seal. These impurities may enter the seal chamber, causing wear on the stationary and rotating rings, reducing the smoothness of the seal faces, and thus inducing leakage. Simultaneously, the presence of pollutants can obstruct the flow of cooling water, preventing it from effectively carrying away the heat generated at the seal faces, further exacerbating wear and temperature rise. The chemical composition of the cooling water can also affect the materials of the mechanical seal. Cooling water containing high concentrations of corrosive agents can accelerate the corrosion of seal materials, reducing their service life. If the materials used in the mechanical seal are not corrosion-resistant, prolonged exposure to such cooling water can lead to cracks, pitting, or spalling on the seal faces, ultimately causing leakage. The temperature of the cooling water is crucial for the performance of the mechanical seal. If the cooling water temperature is too high, it may cause softening or aging of the seal materials, reducing their elasticity and sealing effectiveness. As temperature increases, the seal components may not maintain the designed tight contact, leading to leakage.

Anhui Shengshi Datang Pump Industry is committed to providing customers with the best technology and services, always putting customers at the core.

  Introduction to Pneumatic Diaphragm Pumps

A pneumatic diaphragm pump uses compressed air as its driving power source. It typically consists of components such as an air inlet, air distribution valve, balls, ball seats, diaphragms, connecting rods, central bracket, pump inlet, and exhaust outlet. Once it receives a control command, the pump starts operating by utilizing air pressure and its special internal structure to transfer materials. It has low requirements for the properties of the conveyed medium and can handle a wide range of substances, including solid–liquid mixtures, corrosive acid and alkali liquids, volatile, flammable, and toxic fluids, as well as viscous materials. It offers high working efficiency and simple operation. However, due to aging parts or improper use, diaphragm pump failures may occur during operation.

A. Materials

Pneumatic diaphragm pumps are commonly made from four materials: aluminum alloy, engineering plastics, cast alloy, and stainless steel. Depending on the medium being handled, the pump materials can be adjusted accordingly to meet the diverse needs of users. Owing to its adaptability to different environments, the pump can handle materials that conventional pumps cannot, earning it wide recognition among users.

B. Working Principle

The diaphragm pump operates by using a power source to drive the piston, which in turn moves hydraulic oil back and forth to push the diaphragm, thereby achieving suction and discharge of liquids. When the piston moves backward, the change in air pressure causes the diaphragm to deform and concave outward, increasing the chamber volume and decreasing pressure. When the chamber pressure drops below the inlet pressure, the inlet valve opens, allowing fluid to flow into the diaphragm chamber. Once the piston reaches its limit, the chamber volume is at its maximum and the pressure is at its minimum. After the inlet valve closes, the suction process is complete, and liquid filling is achieved.

As the piston moves forward, the diaphragm gradually bulges outward, decreasing the chamber volume and increasing internal pressure. When the pressure in the chamber exceeds the resistance of the outlet valve, the liquid is expelled. Once the piston reaches the external limit, the outlet valve closes under gravity and spring force, completing the discharge process. The diaphragm pump then proceeds to the next suction and discharge cycle. Through continuous reciprocation, the diaphragm pump effectively transfers the liquid.

C. Characteristics

1. Low heat generation: Powered by compressed air, the exhaust process involves air expansion, which absorbs heat, reducing the operating temperature. Since no harmful gases are emitted, the air properties remain unchanged.

2. No spark generation: As it does not rely on electricity, static charges are safely discharged to the ground, preventing spark formation.

3. Can handle solid particles: Due to its positive displacement working principle, there is no backflow or clogging.

4. No impact on material properties: The pump merely transfers fluids and does not alter their structure, making it suitable for handling chemically unstable substances.

5. Controllable flow rate: By adding a throttling valve at the outlet, the flow rate can be easily adjusted.

6. Self-priming capability.

7. Safe dry running: The pump can operate without load without damage.

8. Submersible operation: It can work underwater if needed.

9. Wide range of transferable liquids: From water-like fluids to highly viscous substances.

10. Simple system and easy operation: No cables or fuses are required.

11. Compact and portable: Lightweight and easy to move.

12. Maintenance-free operation: No lubrication needed, eliminating leakage and environmental pollution.

13. Stable performance: Efficiency does not decline due to wear.

  Common Failures and Causes

Although pneumatic diaphragm pumps are compact and occupy little space, their internal structure is complex, with many interconnected components. Failure of any single part can lead to operational problems. Unusual noise, fluid leakage, or control valve malfunctions are typical warning signs. Timely maintenance is essential. Component wear and aging caused by friction are also major sources of malfunction.

A. Pump Not Operating

1. Symptoms: When starting, the pump either does not respond or stops running shortly after starting.

2. Causes:

a. Circuit issues such as disconnection or short circuit prevent proper operation.

b. Severe component damage — for example, worn ball valves or damaged air valves — leads to loss of pressure and system shutdown.

B. Blocked Inlet or Outlet Pipeline

1. Symptoms: Reduced working pressure, weak suction, and slow fluid transfer.

2. Causes:

a. High-viscosity materials adhere to the inner pipe walls, reducing diameter and smoothness, increasing resistance.

b. Use of multiple materials without thorough cleaning causes chemical reactions between residues, affecting normal operation.

C. Severe Ball Seat Wear

Continuous friction wears down the surface of the ball seat, creating gaps between the ball and seat. This may cause air leakage and reduced pump output.

D. Severe Ball Valve Wear

1. Symptoms: Irregular ball shape, visible surface pitting, or heavy corrosion reducing ball diameter.

2. Causes:

a. Manufacturing inconsistencies cause mismatch between the ball and seat.

b. Long-term operation under friction and corrosive environments accelerates valve damage.

E. Irregular Pump Operation

1. Symptoms: The pump fails to complete normal suction and discharge cycles even after adjustment.

2. Causes:

a. Worn or damaged ball valve.

b. Aged or broken diaphragm.

c. Incorrect system settings.

F. Insufficient Air Supply Pressure or Poor Air Quality

Insufficient air pressure leads to reduced gas volume entering the air chamber, resulting in inadequate force to drive the connecting rod reciprocation. Increasing air pressure typically resolves this issue. Additionally, poor air quality can hinder the movement of the linkage rod and reduce motor speed, weakening pump output.

Comprehensive Guide to Chemical Centrifugal Pumps: From Features to Installation

1.Overview of Chemical Centrifugal Pumps

Chemical centrifugal pumps, as reliable assistants in the chemical industry, have gained widespread popularity due to their outstanding performance characteristics, such as wear resistance, uniform water output, stable operation, low noise, easy adjustment, and high efficiency. Their working principle involves the generation of centrifugal force when the impeller rotates while the pump is filled with water. This force pushes the water in the impeller channels outward into the pump casing. Subsequently, the pressure at the center of the impeller gradually decreases until it falls below the pressure in the inlet pipe. Under this pressure differential, water from the suction pool continuously flows into the impeller, enabling the pump to sustain water suction and supply. With the growing demand for chemical centrifugal pumps across various industries, it is essential to delve into their technical details. Next, Anhui Shengshi Datang will explore 20 technical questions and answers about chemical centrifugal pumps with you, unveiling the technical mysteries behind them.

2.Performance Characteristics of Chemical Centrifugal Pumps

Chemical centrifugal pumps are highly favored for their wear resistance, uniform water output, and other features. They possess multiple characteristics, including adaptability to chemical process requirements, corrosion resistance, tolerance to high and low temperatures, resistance to wear and erosion, reliable operation, minimal or no leakage, and the ability to transport liquids in critical states.

3.Technical Details of Chemical Centrifugal Pumps

a. Definition and Classification

Chemical centrifugal pumps are devices that generate centrifugal force through impeller rotation and can be classified into vane pumps, positive displacement pumps, etc. Based on their working principles and structures, chemical pumps are categorized into vane pumps, positive displacement pumps, and other forms. Vane pumps utilize the centrifugal force generated by impeller rotation to enhance the mechanical energy of liquids, while positive displacement pumps transport liquids by altering the working chamber volume. Additionally, there are special types like electromagnetic pumps, which use electromagnetic effects to transport conductive liquids, as well as jet pumps and airlift pumps that utilize fluid energy to convey liquids.

b. Advantages and Performance Parameters

Centrifugal pumps offer high flow rates, simple maintenance, and core metrics such as output power and efficiency. Centrifugal pumps exhibit several notable advantages in application. First, their single-unit output provides a large and continuous flow without pulsation, ensuring smooth operation. Second, their compact size, lightweight design, and small footprint reduce costs for investors. Third, the simple structure, minimal vulnerable parts, and long maintenance intervals minimize operational and repair efforts. Furthermore, centrifugal pumps feature excellent adjustability and reliable operation. Notably, they require no internal lubrication, ensuring the purity of the transported fluid without contamination from lubricants.

 c. Types of Losses and Efficiency

Main hydraulic losses include vortex, resistance, and impact losses, with efficiency being the ratio of effective power to shaft power. Hydraulic losses in centrifugal pumps, also known as flow losses, refer to the difference between theoretical head and actual head. These losses occur due to friction and impact during liquid flow within the pump, converting part of the energy into heat or other forms of energy loss.

Hydraulic losses in centrifugal pumps primarily consist of three components: vortex loss, resistance loss, and impact loss. These combined effects create the difference between theoretical and actual head. The efficiency of a centrifugal pump, also called mechanical efficiency, is the ratio of effective power to shaft power, reflecting the extent of energy loss during operation.

d. Speed and Power

Speed affects flow rate and head, with power measured in watts or kilowatts. The speed of a centrifugal pump refers to the number of rotations the pump rotor completes per unit time, measured in revolutions per minute (r/min). The power of a centrifugal pump, or the energy transmitted to the pump shaft by the prime mover per unit time, is also known as shaft power, typically measured in watts (W) or kilowatts (KW).

e. Head and Flow Rate

When speed changes, flow rate and head vary according to square or cubic relationships. Adjusting the speed of a centrifugal pump alters its head, flow rate, and shaft power. For unchanged media, the ratio of flow rate to speed exceeds the speed itself, while the ratio of head to speed equals the square of the speed ratio. Meanwhile, the ratio of shaft power to speed equals the cube of the speed ratio.

f. Number of Blades and Materials

The number of blades typically ranges from 6 to 8, with materials requiring corrosion resistance and high strength. The number of blades in a centrifugal pump impeller is a critical parameter directly affecting pump performance. Generally, the blade count is set based on specific applications and needs, ensuring efficient and stable operation. Common manufacturing materials include gray cast iron, acid-resistant silicon iron, alkali-resistant aluminum cast iron, chromium stainless steel, etc.

g. Pump Casing and Structure

The pump casing collects liquid and increases pressure, with common structures including horizontal split-type designs. The pump casing plays a vital role in centrifugal pumps. It not only collects liquid but also gradually reduces liquid velocity through specific channel designs. This process effectively converts part of the kinetic energy into static pressure, enhancing liquid pressure while minimizing energy loss due to oversized channels. Common pump casing structures include horizontal split-type, vertical split-type, inclined split-type, and barrel-type designs.

With the continuous updates in process technology for chemical enterprises, stricter demands are placed on the stable operation of chemical centrifugal pumps. These pumps play a crucial role in the chemical industry, where their performance stability directly impacts the smoothness of the entire production process. Therefore, a deep understanding and rational selection of pump casing support forms are essential for ensuring the stable operation of chemical centrifugal pumps.

Welcome everyone to join Anhui Shengshi Datang in learning about submersible pumps.

 Common Faults of Submersible Pumps

1. Electric Leakage

Electric leakage is one of the most common and dangerous faults in submersible pumps, as it poses a serious threat to human safety. When the switch is turned on, the leakage protection device in the transformer distribution room may automatically trip. Without such protection, the motor could burn out. Water entering the pump body lowers the insulation resistance of the submersible pump. Long-term use can cause wear on the sealing surfaces, allowing water to seep in and create leakage.

Once leakage occurs, the motor should be removed and dried in an oven or with a 100–200 Ω lamp. Afterward, replace the mechanical seal, reassemble the pump, and then it can be safely operated again.

2. Oil Leakage

Oil leakage in a submersible pump is mainly caused by severe wear or poor sealing of the oil seal box. When oil leakage occurs, oil stains can often be seen near the water inlet. Remove the screws at the inlet and carefully inspect the oil chamber for water intrusion. If water is found inside, it indicates poor sealing and the oil seal box should be replaced immediately to prevent water from entering the oil chamber and damaging the motor.

If oil stains appear around the cable connection, the leakage is likely from inside the motor, possibly due to a cracked joint or substandard lead wire. After identifying the cause, replace the defective parts and check the motor’s insulation. If the insulation is compromised, replace the oil inside the motor with fresh oil.

3. Impeller Does Not Rotate After Power-On

If the pump emits an AC humming sound when powered on but the impeller does not rotate, cut off the power and try to manually rotate the impeller. If it does not move, it is jammed and the pump must be disassembled for inspection. If the impeller moves freely but still does not rotate when powered, the likely cause is worn bearings. The magnetic field generated by the stator may attract the rotor, preventing it from turning. When reassembling the pump, ensure the impeller rotates freely to eliminate this issue.

4. Low Water Output

After removing the rotor, check whether it rotates smoothly. When dismantling the pump, inspect for looseness between the lower part of the pump and the bearing. If the rotor has dropped, it means the rotor’s rotational force is reduced, resulting in decreased power output. Place an appropriate washer between the bearing and the rotor, reassemble the pump, and perform a test run to gradually identify and resolve the fault.

   Submersible Pump Maintenance

1. Correct Assembly and Disassembly Methods

Before disassembly, mark the joint between the end cover and the base to ensure proper alignment during reassembly and avoid shaft misalignment. After removing the impeller, use the heat expansion and cold contraction method — heating and lightly tapping to detach it. During disassembly, carefully inspect the winding for damage and analyze the cause. When removing damaged windings, protect the iron core and plastic insulating rings to prevent damage to insulation or electromagnetic components. Always use proper tools and techniques to avoid harming other parts. 

2. Analysis of Winding Burnout Causes

During motor disassembly, avoid moving the assembly excessively to prevent grounding or short circuits when installing new windings. When rewinding, always use wires from reliable manufacturers to ensure quality. For low-insulation areas, use insulation materials of sufficient thickness and ensure padding is properly installed. Do not use sharp tools to scrape the wires during winding, as this may damage insulation.

3. Proper Waterproof Insulation of Cable Joints

At the joint, remove the sheath and insulation layer, and clean any oxidation from the copper wire surface. Wrap the connection securely with polyester adhesive tape to form a mechanical protective layer and ensure waterproof insulation. 

4. Preparations Before Powering On

Before energizing the motor, fill it with clean water to help cool the windings and provide lubrication. Operating the motor without water can cause severe damage. In winter, be sure to drain the water from the motor to prevent freezing and cracking.

5. Correct Application of Insulating Varnish to Motor Coils

After forming the stator, immerse it completely in insulating varnish for about 30 minutes before removing it. Then brush varnish evenly on the surface. Since varnish has high viscosity and poor penetration, brushing alone may not provide a uniform coating or meet required insulation quality standards.

   Proper Maintenance Practices

Proper maintenance is crucial for extending the service life and efficiency of submersible pumps. If the pump will not be used for an extended period, it should be removed from the well and all components should be inspected to prevent rusting. For pumps with long service history, disassemble and clean all internal parts, including removing screws and flushing sediment from the impeller. Severely worn components should be replaced promptly.

If rust is found, clean the affected areas, apply oil, and reassemble. Always check the sealing parts. Store electric pumps in a dry, well-ventilated place to prevent moisture damage. Add lubricating oil periodically, using low-viscosity, water-insoluble oil.

Avoid long-term overload operation or pumping water containing large amounts of sediment. When the pump runs dry, limit the duration to prevent motor overheating and burnout. During operation, the operator should continuously monitor the working voltage and water flow. If either exceeds the specified range, the motor should be stopped immediately to prevent damage.

Visiting Liang Zhiquan, the Product Director of QSTECH CO., LTD. (QSTECH).

In the past few years, LED all-in-one machines have achieved significant success across various industries and sectors. Especially in areas like advertising, commerce, conferences, education, theaters, stadiums, exhibitions, and entertainment, LED all-in-one machines have become the mainstream display devices. However, there's one company that not only leads in the domestic LED display field but also holds the record for the highest market share in the LED integrated display industry in China*. This company is QSTECH CO., LTD. (referred to as "QSTECH" below). The editorial team of "LED display" had the privilege of interviewing Liang Zhiquan, the Product Director of QSTECH, to delve into the secrets behind QSTECH's success in the LED integrated display field.

Craftsmanship Creates Quality, Setting the Benchmark for Excellence

In recent years, QSTECH's LED all-in-one machines have consistently stood out due to their outstanding product quality and continuous innovation, earning the favor of consumers in the market. Liang Zhiquan explained, "QSTECH offers LED all-in-one machines with 16:9 aspect ratios in models ranging from 120 to 220 inches, with resolutions such as 2K and 4K; as well as ultra-wide 32:9 screens in models like 199, 249, and 299 inches with 4K resolution." The core strengths of QSTECH's LED all-in-one machines lie in their convenience through an intelligent system that introduces new application methods, energy efficiency and environmental friendliness through advanced power and system design, and exceptional display quality achieved through meticulous calibration using QSTECH's systems.

QSTECH places a strong emphasis on technological innovation and research and development, boasting a team of highly skilled engineers who continuously explore and study new technologies. They consistently launch high-quality LED integrated display products that meet the market's demands. "For four consecutive years, we have ranked first in both shipments and sales in the LED integrated display industry*," Liang Zhiquan proudly stated. In various industries and scenarios, such as large and medium-sized conference venues, exhibition halls, and small briefing rooms, QSTECH's LED all-in-one machines have been widely utilized. Liang Zhiquan expressed his pride, stating that QSTECH's products are highly integrated and user-friendly, evident in cases like the transformation of a crucial meeting room for a certain enterprise, where QSTECH's LED integrated display meets all application needs with a single power cable.

Seizing Opportunities, Planning Development, and Drawing a New Chapter

The era of the pandemic has accustomed people to remote work, including remote meetings and training among teams. In the post-pandemic era, communication, training, and other activities within and between companies are expected to experience explosive growth. With the diversification of businesses, the demand for large-sized, user-friendly LED all-in-one machines has surged for various local and remote meetings, trainings, and more. Liang Zhiquan believes that LED all-in-one machines will gradually replace traditional displays in spaces below 10 square meters or within spaces of 60 to 300 square meters, as the cost of LED all-in-one machines decreases, driving an accelerated rate of replacement.

QSTECH is poised to respond to this trend by focusing on customer needs, deeply understanding the current market, researching the demands of various stakeholders, and considering factors such as touch experience and visual quality to create products that align with user preferences. Liang Zhiquan noted, "QSTECH's integrated design combines receiver cards, power supplies, and interface boards on a single card with wireless connections. This design shift from 'soft connections' to 'hard connections' eliminates issues caused by aging cables or loose connections, enhancing product stability and reliability." According to related data, QSTECH has held the top market share in the Chinese LED integrated display industry from 2019 to 2022, and updated data shows that its market share exceeded 40% in Q1 of 2023*. Additionally, QSTECH boasts a highly skilled team that possesses deep understanding and mastery of their products, thus establishing a strong brand image and reputation in the market. This marks the beginning of a new chapter of high-quality development for QSTECH's LED all-in-one machines.

Forging Ahead on a New Journey, Riding the Momentum toward the Future

The underlying logic of LED all-in-one machines has evolved from complex engineering to user-friendly integration and high levels of integration. In the future, LED all-in-one machines are expected to appear in even more industries and application scenarios. Wherever a large-sized display is needed, LED all-in-one machines will have a presence. The convenience, energy efficiency, and exceptional display quality of LED all-in-one machines have transformed them from mere LED screens into versatile carriers of various applications. QSTECH is prepared to unleash its potential in the new journey of the future.

It's important to note that while LED all-in-one machines have proliferated like mushrooms after rain, not all products on the market are of high quality. Some products labeled as LED all-in-one machines have provided users with subpar experiences, causing good products to not spread as quickly as expected. Liang Zhiquan suggests that the industry should promptly improve the standards for LED all-in-one machines, ensuring that users have access to safe, user-friendly, and visually appealing LED integrated display products. In the future, QSTECH will further enhance technological innovation and research and development to provide users with higher quality, more advanced LED display products and services.

Lastly, Liang Zhiquan pointed out that Micro LED all-in-one machines are currently conceptual products. True full-process Micro LED all-in-one machines still face many technical challenges and cost pressures. However, looking at the development trend from a technological perspective and based on scenarios, there is significant market potential for Micro LED all-in-one machines in the future. Liang Zhiquan is confident that QSTECH will embrace the opportunities and challenges of the LED integrated display market and will surely make remarkable progress in the development of Micro LED all-in-one machines.

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Magnetic pumps are commonly used pumps, and demagnetization is a relatively frequent cause of damage. Once demagnetization occurs, many people may find themselves at a loss, which could lead to significant losses in work and production. To prevent such situations, Anhui Shengshi Datang will briefly explain today why magnetic pumps experience demagnetization.

1. Magnetic Pump Structure and Principle

1.1 Overall Structure

The main components of a magnetic pump's overall structure include the pump, the motor, and the magnetic coupler. Among these, the magnetic coupler is the key component, encompassing parts such as the containment shell (isolating can) and the inner and outer magnetic rotors. It significantly impacts the stability and reliability of the magnetic pump.

1.2 Working Principle

A magnetic pump, also known as a magnetically driven pump, operates primarily on the principle of modern magnetism, utilizing the attraction of magnets to ferrous materials or the magnetic force effects within magnetic cores. It integrates three technologies: manufacturing, materials, and transmission. When the motor is connected to the outer magnetic rotor and the coupling, the inner magnetic rotor is connected to the impeller, forming a sealed containment shell between the inner and outer rotors. This containment shell is firmly fixed to the pump cover, completely separating the inner and outer magnetic rotors, allowing the conveyed medium to be transmitted into the pump in a sealed manner without leakage. When the magnetic pump starts, the electric motor drives the outer magnetic rotor to rotate. This creates attraction and repulsion between the inner and outer magnetic rotors, driving the inner rotor to rotate along with the outer rotor, which in turn rotates the pump shaft, accomplishing the task of conveying the medium. Magnetic pumps not only completely solve the leakage problems associated with traditional pumps but also reduce the probability of accidents caused by the leakage of toxic, hazardous, flammable, or explosive media.

1.3 Characteristics of Magnetic Pumps

(1) The installation and disassembly processes are very simple. Components can be replaced anywhere at any time, and significant costs and manpower are not required for repair and maintenance. This effectively reduces the workload for relevant personnel and substantially lowers application costs.

(2) They adhere to strict standards in terms of materials and design, while requirements for technical processes in other aspects are relatively low.

(3) They provide overload protection during the conveyance of media.

(4) Since the drive shaft does not need to penetrate the pump casing, and the inner magnetic rotor is driven solely by the magnetic field, a completely sealed flow path is truly achieved.

(5) For containment shells made of non-metallic materials, the actual thickness is generally below about 8 mm. For metallic containment shells, the actual thickness is below about 5 mm. However, due to the thick inner wall, they will not be punctured or worn through during the operation of the magnetic pump.

2. Main Causes of Demagnetization in Magnetic Pumps

2.1 Operational Process Issues

Magnetic pumps represent relatively new technology and equipment, requiring high technical proficiency during application. After demagnetization occurs, operational and process aspects should first be investigated to rule out problems in these areas. The investigation content includes six parts:

(1) Check the magnetic pump's inlet and outlet pipelines to ensure there are no issues with the process flow.

(2) Check the filter device to ensure it is free of any debris.

(3) Perform priming and venting of the magnetic pump to ensure no excess air remains inside.

(4) Check the liquid level in the auxiliary feed tank to ensure it is within the normal range.

(5) Check the operator's actions to ensure no errors occurred during operation.

(6) Check the maintenance personnel's operations to ensure they complied with relevant standards during maintenance.

2.2 Design and Structural Issues

After thoroughly investigating the above six aspects, a comprehensive analysis of the magnetic pump's structure is necessary. The sliding bearings play a cooling role when the magnetic pump conveys the medium. Therefore, it is essential to ensure sufficient medium flow rate to effectively cool and lubricate the gap between the containment shell and the sliding bearings, and the friction between the thrust ring and the shaft. If there is only one return hole for the sliding bearings and the pump shaft is not interconnected with the return hole, the cooling and lubrication effect can be reduced. This prevents complete heat removal and hinders maintaining a good state of liquid friction. Ultimately, this can lead to seizure of the sliding bearings (bearing lock-up). During this process, the outer magnetic rotor continues to generate heat. If the inner magnetic rotor's temperature remains within the limit, the transmission efficiency decreases but can potentially be improved. However, if the temperature exceeds the limit, it cannot be remedied. Even if it cools down after shutdown, the reduced transmission efficiency cannot recover to its original state, eventually causing the magnetic properties of the inner rotor to gradually diminish, leading to demagnetization of the magnetic pump.

2.3 Medium Properties Issues

If the medium conveyed by the magnetic pump is volatile, it can vaporize when the internal temperature rises. However, both the inner magnetic rotor and the containment shell generate high temperatures during operation. The area between them also generates heat due to being in a vortex state, causing the internal temperature of the magnetic pump to rise sharply. If there are issues with the magnetic pump's structural design, affecting the cooling effect, then when the medium is delivered into the pump, it may vaporize due to the high temperature. This causes the medium to gradually turn into gas, severely affecting the pump's operation. Additionally, if the static pressure of the conveyed medium within the magnetic pump is too low, the vaporization temperature decreases, inducing cavitation. This can halt the medium conveyance, ultimately causing the magnetic pump bearings to burn out or seize due to dry friction. Although the pressure at the impeller varies during operation, centrifugal force effects can cause very low static pressure at the pump inlet. When the static pressure falls below the vapor pressure of the medium, cavitation occurs. When the magnetic pump contacts the cavitating medium, if the cavitation scale is small, it might not significantly affect the pump's operation or performance noticeably. However, if the medium's cavitation expands to a certain scale, a large number of vapor bubbles form inside the pump, potentially blocking the entire flow path. This stops the flow of medium inside the pump, leading to dry friction conditions due to the ceased flow. If the pump's structural design results in an inadequate cooling effect, the containment shell temperature can become excessively high and cause damage, subsequently increasing the temperature of both the medium and the inner magnetic rotor.

The horizontal multistage centrifugal pump is a type of fluid machinery primarily used for liquid transportation. It features high delivery efficiency and can be applied to the transfer of crude oil and chemical products, intermediate process liquids, cooling and circulation systems, as well as waste treatment and discharge. A petrochemical plant typically operates thousands of horizontal multistage centrifugal pumps. Prolonged operation inevitably leads to wear and technical failures, which can reduce operating efficiency and increase both production costs and the risk of shutdowns for maintenance. Currently, the petroleum industry generally adopts the DG-2499Y horizontal multistage centrifugal pump. Anhui Shengshi Datang will conduct an in-depth analysis of its technical parameters, explore possible causes of technical failure, and propose targeted maintenance recommendations to provide a systematic repair plan, ensuring equipment stability and continuous plant operation.

   Technical Parameters

The horizontal multistage centrifugal pump consists of multiple pump stages connected in series, with each stage including an impeller and a corresponding diffuser. In each stage, the liquid gains kinetic energy through the impeller, which is then partially converted into pressure energy in the diffuser—thus progressively increasing the total output pressure of the pump.

This pump features a compact structure, ease of maintenance, and high efficiency in handling large flow rates, meeting high head requirements. Its rated flow ranges from 6 to 1000 m³/h, with a rated head between 40 and 2000 m. Operating speeds include 3500 r/min, 2900 r/min, 1750 r/min, and 1450 r/min, with a working frequency of 50 Hz or 60 Hz.

Taking the DG-2499Y horizontal multistage centrifugal pump as an example, its key technical features include:

 a. Two bearings installed on the front and rear shafts.

 b. The pump and motor are connected by an elastic pin coupling, with the motor rotating clockwise during operation.

 c. The suction inlet is set horizontally, while the discharge outlet is vertical.

 d. Bearings are lubricated with grease, and the shaft seal can be either a packing seal or a mechanical seal.

   Failure Cause Analysis

A. Dry Running Without Lubrication

Dry running occurs when the pump operates without sufficient lubrication due to failure or absence of lubricant. For the DG-2499Y pump, the bearings and shaft sleeves rely on lubrication to minimize friction and wear. Without lubrication, these parts can quickly wear out due to high friction and heat. The packing seal’s effectiveness may also decrease, leading to shaft seal failure and leakage. Excessive bearing wear can cause instability, resulting in impeller imbalance, increased vibration and noise, and reduced efficiency and lifespan. In extreme cases, complete bearing failure may occur, causing severe mechanical damage and shutdown.

B. Chemical Corrosion

In petrochemical applications, the DG-2499Y pump often handles chemically aggressive media such as crude oil, intermediate refinery products, and other chemical process fluids. These media may contain corrosive compounds such as sulfides, acids, and alkalis, which can attack metal components like impellers, shafts, and sleeves. Prolonged exposure leads to structural weakening, cracking, or pitting corrosion. Factors such as temperature, concentration, and flow velocity significantly affect corrosion rate. For instance, high temperatures accelerate corrosion, while high velocities can cause erosion–corrosion, where chemical attack and mechanical wear act simultaneously. Chemical reactions may also deteriorate packing and seal materials, reducing sealing performance and causing leakage or pump failure.

C. Overheating During Operation

During long-term operation, friction, poor heat dissipation, or high process fluid temperature may lead to overheating. Bearing overheating is common, often caused by insufficient or poor-quality lubricant. Under high-speed rotation, frictional heat between shaft sleeves can degrade material properties. Impellers and sealing rings may lose mechanical strength at elevated temperatures, reducing pump efficiency or causing structural damage. Insufficient flow in the recirculation or discharge lines can also lead to overheating, resulting in component fatigue, accelerated wear, and reduced service life.

D. Solid Particle Contamination

In petrochemical operations, pumps may be damaged by solid impurities in the conveyed medium—such as unreacted catalyst particles, sediments, corrosion products, or small debris. When these enter the pump, especially through the suction section and impeller, they increase wear on these components and reduce efficiency. Continuous particle erosion can severely wear sealing rings, shafts, and sleeves, leading to seal failure and performance degradation.

E. Cavitation

Cavitation occurs when the pressure at the suction side drops to or below the liquid’s vapor pressure, forming vapor bubbles that collapse in high-pressure regions. The resulting shock waves damage impellers and internal components. This phenomenon is common in petrochemical applications where volatile solvents or gases are present, especially under high-temperature or low-pressure conditions.

   Key Maintenance Techniques

A. Zero-Flow Issue After Startup

 a. When a DG-2499Y pump exhibits zero flow after startup, technicians should perform precise diagnostics:

 b. Use pressure testing instruments to verify system sealing, ensuring no gas or liquid leakage, especially at the shaft seal and packing areas. 

 c. Monitor flow and pressure readings to identify internal blockages or piping faults. 

 d. Check motor-pump alignment to ensure efficient power transmission through the coupling.

 e. Use infrared thermography to detect heat concentration indicating friction hotspots.

 f. Replace or repair faulty components (e.g., impellers, bearings) and realign using laser tools.

 g. Ensure all maintenance steps meet petrochemical safety and technical standards for stable operation.

B. Flow Rate Troubleshooting

 a. Flow issues often result from chemical corrosion, solid contamination, or cavitation. Maintenance should include:

 b. Evaluating the pump’s Q–H (flow–head) curve to determine deviations.

 c. Cleaning or replacing worn or fouled impellers.

 d. Inspecting and replacing worn sealing rings and bearings.

 e. Measuring actual vs. theoretical flow using flowmeters and adjusting inlet valves as needed.

 f. Checking for cavitation and optimizing NPSH (Net Positive Suction Head) conditions to prevent vapor ingestion.

 g. Detecting blockages or leaks in the pipeline with ultrasonic flow and pressure sensors and repairing as required.

C. Overload in the Drive System

 a. To resolve motor or drive overload:

 b. Conduct full performance tests using instruments like clamp ammeters and power analyzers to ensure operation within rated limits.

 c. Inspect impellers, bearings, and seals for wear or damage that may increase load.

 d. Remove internal blockages and ensure smooth fluid flow.

 e. Precisely align the pump and motor to reduce mechanical transmission losses.

D. Bearing Overheating

 a. Maintenance steps include:

 b. Using vibration analyzers to detect abnormal bearing vibration—an early sign of overheating.

 c. Regularly monitoring bearing temperature via infrared thermography; disassemble and replace damaged bearings when necessary.

 d. Inspecting and cleaning the lubrication and cooling systems to ensure proper lubricant flow and quality.

 e. Verifying correct bearing installation and alignment to minimize frictional heat.

E. Vibration Troubleshooting

 a. Pump vibration may result from impeller blockage or imbalance, misalignment, or loose components. Maintenance personnel should:

 b. Use vibration and laser alignment tools to diagnose misalignment.

 c. Adjust bearing preload to prevent overheating and vibration.

 d. Inspect impellers for damage or imbalance and perform dynamic balancing if necessary.

 e. Tighten all fasteners, including shaft sleeve nuts and bolts, to ensure structural stability and safe operation.

In industries such as chemicals, pharmaceuticals, and new materials, the tank farm area serves as a critical transfer point connecting raw material supply with workshop processes. Especially for long-distance liquid transfer from storage tanks to workshops, ensuring safety, sealing performance, and stable conveying becomes the core of equipment selection. Magnetic pumps, with their leak-free and explosion-proof structure, have become the preferred solution for transferring raw materials and finished products in tank farm systems.

1. Transfer Scenario: Challenges from the “Tank Area” to the Workshop

A “tank area” refers to the zone for raw material unloading, product loading, and intermediate material storage. In actual operations, liquids are transferred from tank trucks into storage tanks, typically within a distance of around 20 meters. Next, the material must be conveyed stably through pipelines to workshops located more than 50 meters away.

This type of transfer scenario has three typical characteristics:

A. Long distance and high head requirements: Pipeline lengths often exceed 50 meters; head must account for pipeline resistance and elevation differences.

B. Media are usually volatile or toxic: Such as alcohols, ketones, and organic solvents—requiring excellent system sealing.

C. High explosion-proof requirements and limited maintenance access: Usually located in hazardous areas, demanding reliable, low-maintenance equipment.

2. Why Magnetic Pumps Are Suitable for Tank Area Transfer

Shengshi Datang magnetic pumps use magnetic coupling drive and require no mechanical seals, eliminating leakage risks structurally. For toxic, flammable, or volatile media, magnetic pumps offer true zero-leakage performance.

Through optimized flow channels and efficient magnetic drive systems, Shengshi Datang magnetic pumps ensure stable output even during long-distance transfer, making them especially suitable for high-frequency transfers from tank farms to workshops.

3. Key Points for Pump Selection

A. Head Matching: For pipelines exceeding 50 meters, account for frictional and local resistance, as well as tank liquid level and workshop elevation. It is recommended to design the pump head at 1.2× the actual requirement as a safety margin.

B. Material Selection: Wetted parts should be selected according to the medium’s corrosiveness—stainless steel, fluoroplastic lining, or other corrosion-resistant materials.

C. Flow Rate Determination: Select based on unloading or process requirements, generally using the maximum required flow to avoid insufficient feeding or frequent start–stop cycles.

D. Motor Configuration: Use explosion-proof motors, with a grade not lower than EX d IIB T4, matching the operating conditions to ensure long-term safe operation.

E. Cooling Structure: For easily vaporized liquids, choose magnetic pumps with auxiliary cooling circuits to prevent demagnetization of the inner magnet or local cavitation in the pump chamber.

4. Reference Case

At a fine chemical plant in East China, ethanol is transferred from the tank area to a workshop around 55 meters away. Initially, mechanical-seal centrifugal pumps were used, but frequent leakage and long maintenance cycles caused issues. They were later replaced with fluoroplastic-lined magnetic pumps equipped with explosion-proof motors and auxiliary cooling loops. After three years of operation, no leakage occurred, and maintenance costs dropped by more than 40%.

Long-distance transfer from tank areas to workshops demands high levels of stability and sealing from pumps. Magnetic pumps, with their sealless design and strong corrosion resistance, demonstrate significant advantages in such systems. During selection, factors such as transfer distance, medium characteristics, and site explosion-proof requirements should be thoroughly evaluated. Choosing products from manufacturers with extensive industry experience ensures long-term stable operation. Shengshi Datang Pump Industry’s magnetic pumps have been widely used in such applications and are a reliable choice.