In industrial piping systems, ball valves and globe valves are two of the most commonly used control components. Both are capable of regulating and shutting off fluid flow, yet they differ significantly in structure, working principle, and application scope.

 

If you have ever hesitated between choosing a ball valve or a globe valve while designing or maintaining a fluid system, this article will help you make a clearer and more informed decision.

 

Structure and Working Principle

 

The core component of a ball valve is a spherical disc with a through hole. By rotating the ball 90 degrees, the flow can be quickly started or stopped. Its structure is relatively simple, and the straight-through flow path results in very low flow resistance.

 

A globe valve, on the other hand, uses a disc that moves up and down along the axis of the valve seat. By rotating the stem, the disc gradually presses against or lifts away from the seat, thereby controlling the flow rate.

 

In short:

● A ball valve is a rotary-type valve that enables fast opening and closing.

● A globe valve is a linear-motion valve that provides more precise flow regulation.

 

Flow Characteristics and Control Performance

 

When it comes to fluid control, the differences between the two valves are quite distinct.

 

A ball valve allows fluid to pass almost straight through without changing direction. The internal flow path is linear, resulting in very low flow resistance. This makes it ideal for applications that require quick opening and closing, such as emergency shut-off or systems with frequent operation.

However, because a ball valve opens and closes almost instantaneously, it is not suitable for precise flow regulation. Doing so may cause wear on the sealing surfaces or lead to vibration issues.

 

A globe valve, in contrast, excels at precise flow control. Its disc can be positioned at any degree of opening, allowing operators to fine-tune both flow rate and pressure. The drawback is its more complex structure and the fact that the fluid must change direction as it passes through the valve—resulting in higher pressure drop and flow resistance.

 

In summary:

● Ball Valve: Low flow resistance, fast operation, not suitable for throttling.

● Globe Valve: Precise flow control, higher flow resistance, slower operation.

 

Sealing Performance and Maintenance

 

A ball valve typically uses a soft-sealing structure, such as PTFE, which provides excellent tightness and allows for zero leakage. This makes it widely used in applications involving gas, steam, and liquids where a reliable seal is essential.

When equipped with a metal-seated design, the ball valve can also withstand high-temperature and high-pressure conditions.

In terms of maintenance, its compact structure and few components make disassembly and reassembly very convenient.

 

A globe valve, on the other hand, usually features metal-to-metal sealing surfaces, which can handle higher temperatures and pressures. However, with frequent operation, these sealing surfaces are prone to wear.

During routine maintenance, it is important to inspect the disc and seat regularly for signs of abrasion or damage.

 

Comparison of Application Scenarios

 

Ball valves are widely used in fluid transmission systems for the oil & gas, chemical, and pharmaceutical industries. They are particularly suitable for applications that require rapid on/off operation, low pressure drop, and tight sealing, such as emergency shut-off systems, gas lines, and liquid transfer pipelines.

 

Globe valves are more commonly used in steam systems, cooling-water systems, and other process lines that require precise flow control and pressure regulation, and they perform reliably in high-temperature, high-pressure environments.

 

In short:

● If your system priorities are fast actuation and low flow resistance, choose a ball valve. 

● If you prioritize control accuracy and high-temperature/high-pressure tolerance, a globe valve is the better option.

 

Service Life and Operating Torque

 

Ball valves require only a 90° turn to open or close, resulting in low operating torque and long service life. They are particularly well-suited for automated control systems.

 

Globe valves have a longer stroke and require greater operating force, but their robust structure allows them to withstand frequent flow regulation and control operations.

 

Conclusion

 

When choosing between a ball valve and a globe valve, it is essential to consider the specific operating conditions—such as fluid properties, temperature, pressure, and operation frequency.

 

Ball valves are renowned for their low flow resistance and quick on/off operation, while globe valves play a crucial role in industrial systems due to their precise flow control and high-pressure capability.

 

Making the right valve choice not only affects system efficiency but also has a significant impact on long-term maintenance costs and safety.

 

Q&A (Frequently Asked Questions)

 

Q1: Can a ball valve be used to regulate flow?

A: It is not recommended. Ball valves are primarily designed for on/off control. Keeping them partially open for extended periods may cause seal damage or vibration.

 

Q2: Can a globe valve completely shut off the fluid?

A: Yes. When closed, the globe valve disc presses tightly against the seat, providing good sealing. However, it does not achieve the zero-leakage level of a soft-seated ball valve.

 

Q3: Which valve is more suitable for high-temperature applications?

A: Globe valves are generally better for high-temperature and high-pressure conditions because they often use metal-to-metal seals. Ball valves with soft seals may degrade at elevated temperatures.

 

Q4: Which valve is recommended for automated systems?

A: Ball valves are recommended. Their 90° rotation design allows easy operation with low torque, making them well-suited for integration with electric or pneumatic actuators.

Globe valves are compact, reliable-sealing valves widely used in steam, oil, water, and chemical pipelines.

During long-term operation or frequent cycling, internal components can experience wear, corrosion, or deformation, with valve stem bending being one of the more common issues.

This article provides a professional overview of the main failure points in globe valves, the causes of valve stem bending, and recommended handling methods, helping users determine the appropriate time for repair or replacement.

 

1. Function and Importance of the Valve Stem

 

The valve stem is the “transmission core” of a globe valve, transferring the force from the handwheel or actuator to the valve disc to enable opening and closing.

It not only performs the mechanical transmission but also provides sealing guidance and positioning.

Therefore, any bending or damage to the valve stem can result in difficult operation at best, or sealing failure and valve jamming at worst.

 

2. Common Causes of Valve Stem Bending

 

Excessive Operation or Forced Opening/Closing

If the operator continues to turn the handwheel before the valve is fully open or closed, uneven stress may occur on the stem, causing slight bending or twisting.

 

Misalignment During Installation

When the valve is not installed coaxially with the pipeline, lateral forces act on the stem during operation. Over time, this can lead to bending.

 

High-Temperature Deformation

In high-temperature steam or hot oil systems, improper material selection or poor heat dissipation can cause the stem to bend due to excessive thermal expansion.

 

Blockage by Debris or Deposits

If particles or scale are present inside the valve body, the valve disc may be obstructed during operation, exerting reverse forces on the stem that lead to deformation.

 

Material Fatigue or Corrosion

Prolonged service can cause metal fatigue or corrosion, reducing stem strength and resulting in slight bending or even breakage.

 

3. Can a Bent Valve Stem Still Be Used?

 

In general, it is not recommended to continue using a bent valve stem. The main reasons are:

 

Misalignment of the valve disc and seat: Bending prevents the disc from properly aligning with the seat, reducing sealing performance and potentially causing internal or external leakage.

 

Uneven friction with the packing: This accelerates packing wear and can lead to seal leakage.

 

Heavier operation: A bent stem increases the load on the actuator or handwheel, reducing operational flexibility.

 

Further component damage: Continued use may damage the guide bush and valve disc, potentially leading to complete valve failure.

 

For slight bending, some manufacturers may perform mechanical straightening or replace the stem. However, this must be verified by professional inspection to ensure the stem axis is restored and its strength uncompromised before returning the valve to service.

 

4. Other Common Damage Points in Globe Valves

 

Valve Disc and Seat

Prolonged exposure to high pressure or erosion can cause wear or pitting.

Minor damage can be repaired by welding or grinding, but severe wear requires replacement.

 

Packing Chamber

Aging packing or insufficient compression can lead to leakage.

Regular adjustment or replacement restores proper sealing.

 

Bonnet-to-Body Connection

Gasket aging or loose bolts may cause leaks.

Periodic retightening or gasket replacement is recommended.

 

Stem Threads

Lack of lubrication or severe wear increases operating torque.

Regular application of grease prolongs service life.

 

5. How to Prevent Stem Bending

 

Proper Installation: Ensure the valve is aligned with the pipeline to avoid uneven loads.

Standard Operation: Avoid excessive force or over-travel when opening or closing.

Regular Maintenance: Periodically lubricate the stem threads and inspect guiding components.

Material Selection: Use stainless steel or alloy steel stems in high-temperature or corrosive environments.

Operational Monitoring: If the valve becomes hard to operate, stop immediately and inspect before continuing.

 

6. Conclusion

 

Although the stem is just one component of a globe valve, its straightness and strength directly affect the valve’s sealing performance and service life.

Using a bent stem can lead to leakage and further damage.

Proper installation, careful operation, and routine maintenance are essential for extending valve longevity.

 

Q&A

 

Q1: Can a slightly bent stem be corrected?

Yes, but it must be inspected and realigned by a professional using specialized equipment. Ensure there are no cracks or stress concentrations before reuse.

 

Q2: Can a bent stem be repaired?

If the bend is minor and the metal has not fatigued, repair is possible. Severe deformation or compromised sealing requires stem replacement.

 

Q3: Will a bent stem cause leakage?

Yes. The valve disc may not fully contact the seat, leading to internal leakage. Uneven friction at the packing can also cause external leakage.

 

Q4: How can stem bending be prevented in the future?

Proper valve alignment, regular stem lubrication, and avoiding excessive torque during operation are effective ways to prevent deformation.

1. Long Bonnet Design

2. Selecting Low-Temperature-Resistant Metal Materials

3. Valve Stem Sealing Design Must Accommodate Thermal Contraction

4. Special Material Matching for Valve Seats and Discs

5. Structural Measures to Prevent External Frosting and Freezing

6. Stricter Requirements for Valve Stem Tensile Strength and Low-Temperature Toughness

7. Anti-Condensation and Freeze Protection Design for Actuators

Conclusion: Globe Valves Must Be “Designed for Low Temperature”

Q&A – Frequently Asked Questions

Have you ever considered whether a butterfly valve is suitable for your piping system design? Or have you experienced leakage or operational difficulties when using a butterfly valve under high pressure, high temperature, or viscous media?

 

Butterfly valves are widely used in water, gas, steam, and low-pressure piping systems due to their simple structure, lightweight design, quick operation, and cost-effectiveness. However, they are not suitable for all operating conditions. The following situations require caution or avoidance when selecting a butterfly valve:

 

High-pressure systems

 

Butterfly valves are generally suitable for medium- to low-pressure applications. In high-pressure pipelines, the valve disc and sealing surface may not withstand the pressure, leading to leakage or valve damage. For high-pressure systems, gate valves or ball valves are more appropriate.

 

High-temperature environments

 

High-temperature fluids can cause the butterfly valve’s sealing elements to deform or age, compromising sealing performance. If the pipeline temperature exceeds the valve’s design limits, it is recommended to choose high-temperature-specific valves or metal-to-metal sealed valves.

 

Applications requiring extremely tight sealing

 

Although modern butterfly valves have greatly improved sealing performance, they may still be insufficient for zero-leakage or critically controlled leakage scenarios (e.g., hazardous chemicals or precision gas pipelines). Gate valves or ball valves are more suitable in such cases.

 

Viscous fluids or media containing solid particles

 

The valve disc of a butterfly valve may not fully cut off viscous fluids when closed, and solid particles can jam the disc, affecting operation. For slurries, pulp, or fluids with high solid content, check valves or other appropriate valve types should be considered.

 

Conclusion

 

Butterfly valves are an economical and efficient valve choice; however, in high-pressure, high-temperature, strict-sealing, or complex media conditions, they should be used with caution, or alternative valve types better suited to the application should be selected. Choosing the appropriate valve type not only ensures system safety and reliability but also extends valve service life and reduces maintenance costs.

When you turn on your tap or run a washing machine, have you ever wondered what device quietly controls the water flow?Chances are, it's a small but essential component - the ball valve.

 

A ball valve controls flow by rotating a handle 90 degrees to open or close a hole through the center of a spherical disc. When aligned with the pipeline, the medium (water, oil, or gas) flows freely; when turned perpendicular, the passage is completely blocked. This straightforward mechanism makes it one of the most popular flow-control valves today.

 

Ball valves are found far beyond household systems — they are among the most widely used valves in modern industry. Let’s look at where they make a difference.

 

1. Residential & Commercial Systems — The Everyday Guardian

 

Ball valves are valued for their easy operation and reliable sealing.

● Plumbing: Used as main shut-off valves and for sink, toilet, and appliance connections, typically made of brass or stainless steel.

● Appliances: Washing machines and dishwashers often integrate compact plastic or brass ball valves for automatic water control.

● Gas Lines: A dedicated gas ball valve is installed before stoves or heaters to quickly isolate the gas source in emergencies.

 

2. Oil & Gas — The Power Behind Energy Pipelines

 

This is where ball valves face their toughest conditions.

● Upstream production: Fully welded ball valves are used at wellheads and gathering lines for isolation and flow control under high pressure.

● Long-distance pipelines: Full-bore ball valves allow pig passage and enable rapid shutdowns in emergencies.

● Refining & petrochemical plants: Valves are selected based on medium characteristics — carbon steel, stainless steel, or alloy — for safe, corrosion-resistant operation.

 

3. Chemical & Pharmaceutical Industries — Clean and Corrosion-Resistant

 

These sectors demand purity and leak-free performance.

● Chemical processing: Stainless steel or PTFE-lined ball valves handle acids, alkalis, and solvents safely.

● Pharmaceutical & biotech systems: Hygienic polished ball valves (3-A, FDA compliant) ensure cleanability and are used for purified water, process fluids, and clean steam.

 

4. Power Generation — The Reliable Supporter

 

Ball valves are used in boiler feedwater, cooling, fuel, and auxiliary systems, ensuring reliable isolation and safety across thermal and nuclear power plants.

 

5. Water & Municipal Engineering — Managing Urban Flow

 

From drinking water to wastewater treatment, ball valves play a key role.

● Water distribution: Large-diameter ball valves segment main lines and isolate pumping stations.

● Wastewater plants: Valves control sludge, treated water, and chemical dosing, typically made with epoxy coating or full stainless steel for durability.

 

6. Pulp, Mining & Other Industries

 

● Pulp & Paper: Controls pulp, steam, and chemicals in processing lines.

● Mining: Handles slurry and abrasive media, requiring wear-resistant materials.

 

Why Are Ball Valves So Popular?

 

● Quick operation: 90° rotation for instant open/close.

● Tight sealing: Excellent shut-off with minimal leakage.

● Low flow resistance: Full-bore design reduces pressure drop.

● Durable & low maintenance: Simple structure, long service life.

● Versatile: Applicable to water, oil, gas, and corrosive media with proper material selection.

 

Conclusion

 

From household plumbing to remote oil fields, ball valves quietly ensure the smooth and safe operation of modern life and industry.

They remain one of the most universal and reliable solutions in fluid control systems.

In industries such as chemical processing, pharmaceuticals, electroplating, and metallurgy, valves are often exposed to highly corrosive media such as strong acids and alkalis. Conventional metal valve bodies can hardly withstand these conditions for long periods. To extend service life and ensure safe system operation, the PTFE Lined Globe Valve has become the preferred solution for many users. With its exceptional corrosion resistance and reliable sealing design, it performs excellently even under harsh and aggressive process conditions.

 

1. Structural Features and Working Principle of the PTFE Lined Globe Valve

 

The PTFE Lined Globe Valve is based on a standard metal globe valve, with key wetted components—such as the valve body, bonnet, disc, and seat—lined with fluoroplastics like PTFE, FEP, or PFA.

These materials possess outstanding chemical inertness and do not react with most chemical substances, effectively isolating the process medium from the metal parts and preventing corrosion.

 

When the valve is closed, the disc moves downward along the valve seat axis to achieve a tight seal. Thanks to the self-lubricating and low-friction characteristics of fluoroplastics, the lined globe valve ensures smooth operation and reliable sealing performance, even in applications involving frequent opening and closing.

 

2. Types of Corrosive Media Suitable for PTFE Lined Globe Valves

 

PTFE Lined Globe Valves can handle a wide range of corrosive fluids. The main applicable media include:

1. Strong Acids

Suitable for hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid, and similar media.

In extremely corrosive environments, such as concentrated sulfuric acid (98%) or hydrofluoric acid, conventional metal valves may suffer severe corrosion within months, whereas PTFE-lined valves can operate reliably for many years.

 

2. Strong Alkalis

Applicable for sodium hydroxide, potassium hydroxide, and other alkaline chemicals. Widely used in systems such as pulp and paper processing, flue gas desulfurization, and alkali recovery.

 

3. Oxidizing Media

Including sodium hypochlorite, hydrogen peroxide, and fuming nitric acid. The PTFE lining effectively resists oxidation reactions, preventing metal ion leaching or structural corrosion.

 

4. Organic Solvents and Mixed Chemicals

Suitable for alcohols, ketones, ethers, esters, phenols, and other organic compounds. Frequently used in pharmaceutical and fine chemical production lines to ensure high-purity fluid handling.

 

3. Temperature and Pressure Range

 

The operating temperature of PTFE Lined Globe Valves primarily depends on the lining material:

PTFE (Polytetrafluoroethylene): Suitable for -29℃ to +180℃

FEP / PFA (Modified Fluoropolymers): Can withstand temperatures up to +200℃

 

Typical design pressures range from PN10 to PN16, making them suitable for low-pressure, medium-temperature corrosive fluid systems. For conditions exceeding these limits, it is recommended to use metal alloy valves or specially coated valves to ensure long-term sealing and safety.

 

4. Typical Application Industries

 

Thanks to their excellent corrosion resistance, PTFE Lined Globe Valves are widely used in:

 

Acid-base neutralization and chemical transfer systems in chemical production lines

Reaction medium control in pharmaceutical and fine chemical processes

Electroplating, metal surface treatment, and pickling systems

Environmental protection equipment, including waste liquid, acid mist, and exhaust gas purification systems

Metallurgical industry, for wet process metallurgy and metal extraction operations

These applications generally demand high reliability and long-term corrosion resistance, making PTFE Lined Globe Valves particularly suitable for such environments.

 

5. Key Maintenance Tips for PTFE Lined Globe Valves

 

Avoid excessive operating torque

Excessive torque may deform the lining or bend the valve stem.

 

Keep pipelines clean

Prevent solid particles from entering the valve to avoid scratching or damaging the lining.

 

Protect valves during long-term shutdowns

Apply protective oil inside the valve cavity and store in a dry environment to prevent lining aging.

 

Regularly inspect sealing performance

Especially in strong acid or alkali systems, perform routine sealing tests and replace aged components promptly.

 

Q&A

 

Q1: Can PTFE Lined Globe Valves be used in high-temperature strong acid systems?

A: Yes, but it is recommended to use PFA lining, which offers higher temperature resistance suitable for high-temperature concentrated acid applications.

 

Q2: Can PTFE Lined Globe Valves be installed in vacuum pipelines?

A: Not recommended. Fluoropolymers may allow slight gas permeation under high vacuum, affecting sealing performance.

 

Q3: What is the typical service life of a PTFE Lined Globe Valve?

A: Under normal conditions, valves can operate reliably for 5–10 years. If the medium is clean and the opening/closing frequency is low, the service life can be even longer.

 

Q4: What should be considered during installation?

A: Flange bolts should be tightened evenly to avoid damaging the lining. Ensure the flow direction matches the valve body arrow.

 

Summary

 

PTFE Lined Globe Valves, with their outstanding corrosion resistance, reliable sealing, and broad medium compatibility, have become essential equipment in chemical and pharmaceutical industries. Proper selection and routine maintenance not only extend valve life but also significantly enhance system safety and operational stability.

In modern industrial and commercial projects, valve selection directly affects system efficiency and maintenance costs. Butterfly valves, with their simple design, reliable sealing, and lightweight construction, have become one of the most common flow control devices in HVAC systems as well as in municipal water supply, wastewater treatment, and cooling water circuits. But what makes butterfly valves stand out in these applications?

 

 

1. Compact Structure and Small Installation Space

 

Compared with other types of valves such as ball valves and gate valves, butterfly valves have a simpler design. They mainly consist of a body, disc, stem, and sealing ring. The disc functions both as a shut-off element and a flow control component, making the overall valve smaller and lighter—ideal for areas with limited space or tightly arranged piping.

 

In HVAC systems, equipment rooms, chilled water pipelines, and fan coil connections often have restricted space. Using butterfly valves can effectively save installation space and reduce the load on supports.

 

 

2. Easy Operation and Quick On/Off

 

Butterfly valves typically achieve full open or full close with just a 90° rotation of the disc. Whether operated manually, pneumatically, or electrically, the valve responds quickly and smoothly. This makes them ideal for applications that require frequent flow adjustments or rapid system shut-off.

 

For example, in cooling tower water circulation, butterfly valves can quickly adjust flow to respond to load changes, ensuring stable system operation.

 

 

3. Excellent Flow Control Performance

 

In low to medium pressure piping systems, butterfly valves offer effective flow regulation. Their disc design creates relatively low resistance and minimal pressure drop, allowing stable flow control across a wide range of openings.

 

In water treatment systems, butterfly valves are used on raw water, treated water, and wastewater lines to precisely control fluid flow, helping optimize the overall process.

 

 

4. Wide Applicability and Cost-Effectiveness

 

Modern butterfly valves are available in a variety of materials, including cast iron, carbon steel, stainless steel, and special alloys. Sealing materials can also be selected according to the medium, such as EPDM, NBR, or PTFE.

 

This versatility allows butterfly valves to perform well not only with clean water and chilled water but also in corrosive media like seawater and chemical solutions.

 

Compared to other valve types, butterfly valves have lower manufacturing and installation costs for the same nominal diameter, making them especially economical for large-diameter applications. For instance, in municipal water main pipelines, butterfly valves with DN600 and above are often standard.

 

 

5. Easy Maintenance and Long Service Life

 

Butterfly valves have a simple structure and are easy to maintain. Most designs use replaceable rubber or elastomeric seals, so routine maintenance generally involves checking seal wear and lubricating the stem.

 

Moreover, the advent of modern triple-offset metal-seated butterfly valves has enhanced reliability and durability, even under high-temperature, high-pressure, or steam service conditions.

 

 

Q&A

 

Q1: Can butterfly valves be used for flow regulation?

Yes. Butterfly valves can not only perform on/off control but also provide stable flow regulation within a certain opening range, making them particularly suitable for throttling in low- to medium-pressure systems.

                                                                                                                                                                                                                      

Q2: Why are butterfly valves not suitable for high-pressure systems?

Due to their structural characteristics, butterfly valves have relatively weaker sealing performance under high-pressure or high-differential-pressure conditions. For high-pressure or high-temperature media, metal-seated or triple-offset butterfly valves should be selected to ensure reliable sealing.

 

Q3: What materials are commonly used for butterfly valves in HVAC systems?

Common materials include cast iron, carbon steel, and stainless steel. Valve bodies are often made of cast iron or ductile iron, while discs may use nickel-plated carbon steel or stainless steel to ensure corrosion and wear resistance.

 

Q4: Are there any installation orientation requirements for butterfly valves?

Generally, butterfly valves can be installed horizontally or vertically. However, for easier operation and maintenance, it is usually recommended to install the stem vertically and ensure the disc aligns with the flow direction when closed.

 

Q5: What advantages do butterfly valves have over gate valves in water treatment systems?

Butterfly valves are more compact, lighter, faster to operate, and more cost-effective. For pipelines that require frequent operation or have limited space, butterfly valves offer a more economical and efficient solution.

Second, avoid operating the pump without material.

The progressive screw pump absolutely must not run dry. If dry running occurs, the rubber stator can instantly overheat due to dry friction and burn out. Therefore, having a properly functioning grinder and clear screens are essential conditions for the normal operation of the pump. For this reason, some pumps are equipped with a dry-run protection device. When material supply is interrupted, the self-priming capability of the pump creates a vacuum in the chamber, which triggers the vacuum device to stop the pump.

 

Third, maintain a constant outlet pressure.

The progressive screw pump is a positive displacement rotary pump. If the outlet is blocked, the pressure will gradually rise, potentially exceeding the predetermined value. This causes a sharp increase in the motor load, and the load on related transmission components may also exceed design limits. In severe cases, this can lead to motor burnout or broken transmission parts. To prevent pump damage, a bypass relief valve is usually installed at the outlet to stabilize the discharge pressure and ensure normal pump operation.

Fourth, reasonable selection of pump speed.

The flow rate of the progressive screw pump has a linear relationship with its speed. Compared to low-speed pumps, high-speed pumps can increase flow and head, but power consumption increases significantly. High speed accelerates the wear between the rotor and stator, inevitably leading to premature pump failure. Furthermore, the stator and rotor of high-speed pumps are shorter and wear out more easily, thus shortening the pump's service life.

 

Using a gear reducer or variable speed drive to reduce the speed, keeping it within a reasonable range below 300 revolutions per minute, can extend the pump's service life several times compared to high-speed operation.

 

Of course, there are many other maintenance methods for progressive screw pumps, which requires us to be more attentive during daily use. Careful observation will contribute significantly to proper pump maintenance.

 

How should faults in progressive screw pumps be handled? This article will mainly introduce methods for troubleshooting progressive screw pumps.

1. Pump body vibrates violently or produces noise:

A. Causes:​ Pump not installed securely or installed too high; damage to the motor's ball bearings; bent pump shaft or misalignment (non-concentricity or non-parallelism) between the pump shaft and the motor shaft.

B. Solutions:​ Secure the pump properly or lower its installation height; replace the motor's ball bearings; straighten the bent pump shaft or correct the relative position between the pump and the motor.

2. Transmission shaft or motor bearings overheating:

A. Causes:​ Lack of lubricant or bearing failure.

B. Solutions:​ Add lubricant or replace the bearings.

3. Pump fails to deliver water:

Causes:​ Pump body and suction pipe not fully primed with water; dynamic water level below the pump strainer; cracked suction pipe, etc.

 

The sealing surface between the screw and the housing is a spatial curved surface. On this surface, there are non-sealing areas such as ab or de, which form many triangular notches (abc, def) with the screw grooves. These triangular notches form flow channels for the liquid, connecting the groove A of the driving screw to grooves B and C on the driven screw. Grooves B and C, in turn, spiral along their helices to the back side and connect with grooves D and E on the back, respectively. Because the sealing surface where grooves D and E connect with groove F (which belongs to another helix) also has triangular notches similar to a'b'c' on the front side, D, F, and E are also connected. Thus, grooves A-B-C-D-E-A form an "∞"-shaped sealed space (If single-start threads were used, the grooves would simply follow the screw axis and connect the suction and discharge ports, making sealing impossible). It's conceivable that many independent "∞"-shaped sealed spaces are formed along such a screw. The axial length occupied by each sealed space is exactly equal to the lead (t) of the screw. Therefore, to separate the suction and discharge ports, the length of the threaded section of the screw must be at least greater than one lead.

 

 

High-temperature magnetic drive pumps are compact, aesthetically pleasing, small in size, and feature stable, user-friendly operation with low noise levels. They are widely used in chemical, pharmaceutical, petroleum, electroplating, food, film processing, scientific research institutions, defense industries, and other sectors for pumping acids, alkaline solutions, oils, rare and valuable liquids, toxic liquids, volatile liquids, and in circulating water equipment, as well as for supporting high-speed machinery. They are particularly suitable for liquids that are prone to leakage, evaporation, combustion, or explosion. It is best to choose an explosion-proof motor for such pumps.

Advantages of High-Temperature Magnetic Drive Pumps:

1. No need to install a foot valve or prime the pump.

2. The pump shaft is changed from dynamic sealing to enclosed static sealing, completely avoiding media leakage.

3. No independent lubrication or cooling water is required, reducing energy consumption.

4. Power transmission is changed from coupling drive to synchronous dragging, eliminating contact and friction. This results in low power consumption, high efficiency, and provides damping and vibration reduction, minimizing the impact of motor vibration on the pump and pump cavitation vibration on the motor.

5. In case of overload, the inner and outer magnetic rotors slip relative to each other, protecting the motor and pump.

6. If the driven component of the magnetic drive operates under overload conditions or the rotor jams, the driving and driven components of the magnetic drive will automatically slip, protecting the pump. Under these conditions, the permanent magnets in the magnetic drive will experience eddy current losses and magnetic losses due to the alternating magnetic field of the driving rotor, causing the temperature of the permanent magnets to rise and leading to the failure of the magnetic drive slip.

 

 

Precautions for Using High-Temperature Magnetic Drive Pumps:

1. Prevent Particle Entry

(1) Do not allow ferromagnetic impurities or particles to enter the magnetic drive or the bearing friction pair.

(2) After transporting media prone to crystallization or sedimentation, flush promptly (fill the pump cavity with clean water after stopping the pump, run for 1 minute, then drain completely) to ensure the service life of the sliding bearings.

(3) When pumping media containing solid particles, install a filter at the pump inlet.

 

2. Prevent Demagnetization

(1) The magnetic torque must not be designed too small.

(2) Operate within the specified temperature conditions; strictly avoid exceeding the maximum allowable media temperature. A platinum resistance temperature sensor can be installed on the outer surface of the isolation sleeve to monitor the temperature rise in the gap area, enabling an alarm or shutdown if the temperature limit is exceeded.

 

3. Prevent Dry Running

(1) Strictly prohibit dry running (operating without liquid).

(2) Strictly avoid running the pump dry or allowing the media to be completely drained (cavitation).

(3) Do not operate the pump continuously for more than 2 minutes with the discharge valve closed, to prevent overheating and failure of the magnetic drive.

 

4. Not for Use in Pressurized Systems:​

Due to the existence of certain clearances in the pump cavity and the use of "static bearings," this series of pumps must absolutely not be used in pressurized systems (neither positive pressure nor vacuum/negative pressure is acceptable).

 

5. Timely Cleaning:​

For media that are prone to sedimentation or crystallization, clean the pump promptly after use and drain any residual liquid from the pump.

 

6. Regular Inspection:​

After 1000 hours of normal operation, disassemble and inspect the wear of the bearings and the end face dynamic ring. Replace any worn-out vulnerable parts that are no longer suitable for use.

 

7. Inlet Filtration:​

If the pumped medium contains solid particles, install a strainer at the pump inlet. If it contains ferromagnetic particles, a magnetic filter is required.

 

8. Operating Environment:​

The ambient temperature during pump operation should be less than 40°C, and the motor temperature rise should not exceed 75°C.

 

9. Media and Temperature Limits:​

The pumped medium and its temperature must be within the allowable range of the pump materials. For engineering plastic pumps, the temperature should be <60°C; for metal pumps, <100°C. The suction pressure should not exceed 0.2MPa, the maximum working pressure is 1.6MPa, for liquids with a density not greater than 1600 kg/m³ and a viscosity not greater than 30 x 10⁻⁶ m²/s, and which do not contain hard particles or fibers.

High-temperature magnetic drive pumps replace dynamic seals with static seals, making the pump's wetted parts fully enclosed. This solves the unavoidable running, dripping, and leaking issues associated with the mechanical seals of other pumps. Manufactured using highly corrosion-resistant materials such as engineering plastics, alumina ceramics, and stainless steel, these pumps offer excellent corrosion resistance and ensure the pumped media remains uncontaminated.

 

Stainless steel submersible pumps are widely used in drainage applications across industries such as pharmaceuticals, environmental protection, food, chemical, and power due to their characteristics of corrosion resistance, hygiene, energy efficiency, environmental friendliness, non-clogging, high flow rate, and strong passage capability. Anhui Shengshi Datang will study together with everyone.

I. Common Causes and Solutions for Insufficient Flow or No Water Output in Stainless Steel Submersible Pumps:

1. The installation height of the pump is too high, resulting in insufficient impeller immersion depth and reduced water output. Control the allowable deviation of the installation elevation and avoid arbitrary adjustments.

2. The pump rotates in the reverse direction. Before trial operation, run the motor without load to ensure the rotation direction matches the pump. If this occurs during operation, check whether the power phase sequence has changed.

3. The outlet valve cannot open. Inspect the valve and perform regular maintenance.

4. The outlet pipeline is blocked, or the impeller is clogged. Clear blockages in the pipeline and impeller, and regularly remove debris from the reservoir.

5. The lower wear ring of the pump is severely worn or blocked by debris. Clean the debris or replace the wear ring.

6. The density or viscosity of the pumped liquid is too high. Identify the cause of the change in liquid properties and address it.

7. The impeller is detached or damaged. Reinforce or replace the impeller.

8. When multiple pumps share a common discharge pipeline, a check valve is not installed or the check valve is not sealing properly. Install or replace the check valve after inspection.

II. Causes of Abnormal Vibration and Instability During Operation of Stainless Steel Submersible Pumps:

1. The anchor bolts of the pump base are not tightened or have become loose. Tighten all anchor bolts evenly.

2. The outlet pipeline lacks independent support, causing pipeline vibration to affect the pump. Provide independent and stable support for the outlet pipeline, ensuring the pump’s outlet flange does not bear weight.

3. The impeller is unbalanced, damaged, or loosely installed. Repair or replace the impeller.

4. The upper or lower bearings of the pump are damaged. Replace the bearings.

III. Causes of Overcurrent, Motor Overload, or Overheating in Stainless Steel Submersible Pumps:

1. The operating voltage is too low or too high. Check the power supply voltage and adjust it.

2. There is friction between rotating and stationary parts inside the pump, or between the impeller and the seal ring. Identify the location of the friction and resolve the issue.

3. Low head and high flow cause a mismatch between the motor power and the pump characteristics. Adjust the valve to reduce the flow, ensuring the motor power matches the pump.

4. The pumped liquid has high density or viscosity. Investigate the cause of the change in liquid properties and adjust the pump’s operating conditions.

5. The bearings are damaged. Replace the bearings at both ends of the motor.

IV. Causes and Solutions for Low Insulation Resistance in Stainless Steel Submersible Pumps:

1. The cable ends were submerged during installation, or the power or signal cable was damaged, allowing water ingress. Replace the cable or signal wire, and dry the motor.

2. The mechanical seal is worn or not properly installed. Replace the upper and lower mechanical seals, and dry the motor.

3. The O-rings have aged and lost their function. Replace all sealing rings and dry the motor.

V. Causes and Solutions for Visible Water Leakage in Pipes or Flange Connections of Stainless Steel Submersible Pump Systems:

1. The pipeline itself has defects and was not pressure-tested.

2. The gasket connection at the flange joint was not properly handled.

3. The flange bolts were not tightened correctly. Repair or replace defective pipes, realign misaligned pipes, and ensure bolts are inserted and tightened freely. After installation, conduct a pressure and leakage test on the entire system. Replace components as necessary.

VI. Internal Leakage in Stainless Steel Submersible Pumps:

Leakage in the pump can lead to insulation failure, bearing damage, alarm activation, and forced shutdown. The main causes include failure of dynamic seals (mechanical seals) or static seals (cable inlet seals, O-rings), and damage to power or signal cables allowing water ingress. Alarms such as water immersion, leakage, or humidity may trigger shutdowns. Before installation, inspect the quality of all sealing components. Ensure proper contact between sealing surfaces during installation. Before operation, check the motor’s phase-to-phase and ground insulation resistance, and ensure all alarm sensors are functional. If leakage occurs during operation, replace all damaged seals and cables, and dry the motor. Do not reuse disassembled seals or cables.

VII. Reverse Rotation After Shutdown of Stainless Steel Submersible Pumps:

1. Reverse rotation occurs after the pump motor is powered off, mainly due to failure of the check valve or flap valve in the outlet pipeline.

2. Before installation, inspect the check valve for correct orientation and ensure the flap valve is centered and operates flexibly. Regularly inspect the check valve or flap valve during operation, and repair or replace damaged components with quality parts.