What is the toy safety test simulation little finger? At present, the safety of children's toy products has become the focus of attention in all countries, and safety is an important indicator for measuring toy products. How to find safety problems and solve them in time when designing and manufacturing toy products? How to avoid product recall due to non-compliance with the standards of toy importing countries? This requires testing of toy products.

Toy safety simulation of small fingers, in line with GB6675, EN71 and other standards of simulation testing, through the imitation of children's fingers, to assess whether touching the surface of the toy or accessories (points and surfaces of the toy) may lead to danger. There are two types of AB, A refers to be used for under 3 years old and B refers to be used for over 3 years old.

The test is performed by extending the articulating reachable probes towards the part or parts of the toy under test in any manner, with each probe rotated 90°to simulate finger joint movement. Finally, a part or component of a toy is considered to be accessible if any part before the shoulder of the shaft can reach it, visually identifying the potential hazards of the toy for everyone.

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Oil content is one of the key indicators for evaluating the performance of all fibers and fiber products except cotton, expressed as the percentage of oil content per unit mass. Different product standards use terms such as“residual fat content,”“oil content,” “dichloromethane-soluble substances,”or“ethanol extractables” as test item names.

1. In chemical fibers, oils primarily originate from additives introduced during spinning and textile processing. These additives prevent or eliminate static buildup while imparting softness and smoothness to the fibers. Oil content is a critical indicator for chemical fibers: excessively low levels may cause static electricity due to friction during production, while excessively high levels impair moisture absorption and increase susceptibility to dust accumulation.

2. The oils in feathers and down primarily originate from residual oils on duck and goose bodies after washing and disinfection processes. Excessive oil content can cause odors and bacterial growth, while insufficient oil affects the external structure of down, making it brittle and reducing the product's warmth.

3. The pupa oil in silk originates from silkworm cocoons. High oil content reduces elasticity, impairs moisture absorption and breathability, and causes odors.

4. As mammals, sheep possess sweat glands. Thus, physiological impurities in wool fibers primarily include sebaceous wax secreted by sebaceous glands, sweat secreted by sweat glands, and shed skin flakes. During raw wool processing, greasy wool sheared from sheep undergoes washing machines to remove sebaceous wax, sweat, and other impurities before drying to produce washed wool. Therefore, the oil content measured in the ethanol extract of washed wool is a key indicator of whether wool grease and sweat have been effectively removed, serving as a benchmark for evaluating washing quality.

5. During the process of combing washed wool into slivers, wool oil is added to impart smoothness, softness, and antistatic properties to loose fibers. This facilitates the passage of wool fibers through combing and spinning equipment, preventing issues like loose fibers, tangling, and breakage. Dichloromethane-soluble substances reflect components in cashmere knitwear extractable by dichloromethane solvent. These primarily include various lubricants added during production, such as spinning oils, detergents, and softeners, along with small amounts of residual natural wool grease wax. If the amount of wool oils added during production is improper, this indicator in the product may be elevated. In severe cases, this can lead to an unpleasant odor and a sticky feel.

6. Test Principle

Utilizing the property that fats and oils are soluble in organic solvents such as ether, dichloromethane, and ethanol, organic solvents are employed to extract fats and oils from the sample. The organic solvent is then evaporated in an oven. The residual fat and oil mass and the sample mass are weighed, and the oil content of the sample is calculated.

7. Test Standards

Standards vary depending on the product type, such as:

GB/T 14272—2011 “Down Garments” Appendix C: Determination of Residual Fat Content

FZ/T 20018—2010 “Determination of Dichloromethane-Soluble Substances in Wool Textiles”

GB/T 24252—2009 “Silk Quilts” Appendix C: Test Method for Oil Content in Fillings

GB/T 6504—2017 “Chemical Fibers—Test Method for Oil Content”

GB/T 6977—2008 Test Methods for Ethanol Extracts, Ash Content, Vegetable Impurities, and Total Alkali Insolubles in Cleaned Wool — Test Method for Ethanol Extracts in Cleaned Wool

8. Are different testing methods interchangeable?

Although oil content testing methods vary for different types of fiber products, the underlying principles remain consistent. These methods utilize solvents such as diethyl ether, dichloromethane, or ethanol to extract fats and oils from the sample. The solvent is then evaporated, leaving behind residual fat. The sample's oil content is calculated using a formula. The QuicExtra Rapid Fiber Oil Extractor is compatible with extraction solvents such as petroleum ether, diethyl ether, and dichloromethane.

9. Testing Equipment

QuicExtra Fiber Oil Rapid Extractor

Also known as the Fiber Oil Rapid Extractor, this device utilizes the principles of solvent penetration and evaporation (using solvents such as petroleum ether, diethyl ether, or other organic solvents) to dissolve oils within textile fibers. This enables the detection of oil content in wool and synthetic fiber samples. Featuring a 3-station design, it rapidly and thoroughly extracts oils within 10 minutes, automatically calculates oil content, and uploads results to the system upon confirmation.

The oil content of different textile fibers varies depending on fiber type and processing requirements. Below are typical oil content ranges for common textile fibers (for reference only), generally expressed as percentages:

Polyester: 0.3% - 1%

Nylon: 0.5% - 2%

Polypropylene: 0.2% - 0.8%

Acrylic: 1% - 3%

Wool: 1% - 3%

Cotton: Below 0.5%

Viscose: 0.3% - 0.8%

Modal: 0.2% - 0.5%

Aramid: 0.1% - 0.5%

Carbon Fiber: Below 0.05%

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In daily life, down penetration can occasionally occur in down jackets and duvets, creating a negative consumer experience.

1. Down Burst Factors

Down feathers in down products contain a large amount of stagnant air. When a down quilt is squeezed, the air inside the down product is expelled through the fabric and needle holes. These airborne particles, called down filaments (hereinafter referred to as flying filaments), are carried by the high-speed airflow and attached to the fabric of the quilt, causing down bursts.

Down bursts can occur for a variety of reasons, such as insufficient fabric density, large needle holes, or poor down quality. This directly impacts the appearance and warmth of the down.

1.1 Down Structure

Because down is composed of protein molecules with a unique tree-like structure, they are easily charged by friction, causing like charges to repel each other and leak through micropores or seams. When down is subjected to external forces, it tends to rebound. During this rebound, air bursts through the fabric, pushing down feathers out from both sides. Furthermore, down is composed of a large number of components, and the tips of down filaments, feathers, and feathers are sharp, making it easy for them to burst through the fabric.

1.2 High Unfinished Down Content

The higher the unfinished down content in a down, the more it will be pierced; conversely, the lower the unfinished down content, the less it will be pierced.

For example, in 90% down that meets the national standard GB/T 14272-2021 "Down Clothing," the detectable unfinished down content can reach up to 10%. With such a high unfinished down content, it's difficult to minimize or eliminate piercing.

Experimental data shows that as the total amount of unfinished down decreases, the number of pinhole-pierced down decreases. When the unfinished down content drops below 3%, the number of pinhole-pierced down decreases by over 80% compared to down with a 12% unfinished down content.

1.3 Low density of the outer and inner lining material, resulting in high air permeability

In existing down jacket construction, the outer fabric, lining, or lining material may all be used to encase the down, and come into close contact and friction with the down.

The lower the density of the outer and inner lining material, the larger the gaps between the fabric fibers, resulting in higher air permeability and an increased chance of flyaway fibers penetrating the fabric. Some companies use calendering or coating processes to reduce fabric air permeability, achieving better initial down-proofing properties. However, as the down jacket is washed and rubbed, the down-proofing effectiveness of calendering or coating diminishes, and down penetration increases. Only by increasing the fabric density to achieve an air permeability of 1-3 mm/s can long-lasting down-proofing properties be achieved.

1.4 Filling Sequence

Currently, most factories use down filling machines. There are two filling processes: filling first and then quilting the down bag; quilting the down bag first and then filling each cell with down. The first filling process is more efficient, as each quilting needle hole compresses some down. These down fibers are close to the needle holes and easily escape through them due to airflow or friction. The second filling process is less efficient, but the quilting needle holes don't compress the down. To escape, the fibers must penetrate the down surrounding them and escape with the airflow, making this process significantly more challenging than the first. Experimental data shows that the amount of down that escapes when quilting first and then filling is reduced by over 60% compared to filling first and then quilting.

Taking all of the above factors into consideration, if companies want to ensure low down penetration in down products, they must implement effective measures and increase product costs to address this issue.

2. Anti-Down Penetration Test Method (Rotating Box Method)

2.1 Ready-to-Draw Down Garments

Principle: The entire test sample is placed in a rotating box of a testing instrument containing shaped silicone rubber balls. The rotating box rotates at a constant speed, bringing the shaped silicone rubber balls to a certain height and impacting the sample within the box, simulating the various squeezing, rubbing, and collision experiences experienced by the test sample during wear. The overall anti-down penetration performance of the garment is evaluated by calculating the number of down, feathers, and down fibers that emerge from the sample per unit area.

2.2 Down Quilts

Principle: Sample bags of fixed size are cut from the down filling area/layer of a finished down quilt or composite down quilt and placed in a rotating box of the testing instrument filled with hard silicone balls. The rotating box rotates at a constant speed, carrying the silicone balls to a certain height, where they impact the sample inside the box, simulating the various squeezing, rubbing, and collision effects that down quilts experience during use. The overall down penetration resistance of the down quilt is evaluated by counting the number of feathers, down, and down fibers that emerge from the sample bag.

[GB/T 12705.2-2009 "Textiles - Test Method for Down Penetration Resistance of Fabrics - Part 2: Rotating Box Method"]

Evaluation of anti-down drilling performance:

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The challenges of wastewater treatment are intensifying

Global wastewater treatment equipment manufacturers face the same challenge: the increasing presence of solids in wastewater, sewage, and surface water, such as wet wipes and other braided contents that can clog pumps. Despite this, especially in an era of shrinking budgets and increasing process complexity, operating wastewater treatment plants must be as efficient, trouble-free, and maintenance-free as possible.

 

Ensuring Reliable and Efficient Wastewater Treatment

 

As experts in wastewater treatment, SUOU offers tailored, end-to-end solutions for pumps, valves, and services, enabling your equipment to operate more efficiently and reliably. Optimized processes enhance equipment performance while reducing maintenance costs.

 

SUOU energy-efficient, low-maintenance pumps can be used in all stages of purification, such as initial purification in influent pumping stations, conveying primary sludge and floating sludge, and activated sludge recycling in biological processes.

 

SUOU: Clog-Free, Completely Reliable

 

SUOU WQ (QW) series wastewater pumps feature clog-free impellers and large free-flow paths, ensuring efficient discharge even with high solids content. Energy-efficient drives, wear-resistant materials, and intelligent automation optimize your processes, enhance equipment performance, and ensure reduced maintenance costs. Longitudinal waterproof inlet pipes and mechanical seals with covered springs are suitable for particularly abrasive wastewater, ensuring a higher level of reliability.

 

SUOU mixers and agitators help break down harmful substances through wastewater circulation. SUOU agitators feature optimized hydraulic performance, rupture-resistant blades, and exceptionally long maintenance intervals, setting the standard in their segment.

 

With decades of market experience, SUOU offers extensive application knowledge, even for large projects. You benefit from the assistance of application and service experts throughout the equipment's lifecycle.

Offering a wide range of products for wastewater treatment:

Dry-installed wastewater pumps

Booster pumps

High-pressure pumps

Inline pumps

Mixers, agitators, and tank purification equipment

Standard pumps

Submersible recirculation pumps

Shell pumps and well submersible pumps

Volcanic pumps

Submersible pumps

 

Applications:

Wastewater treatment plants treating wastewater mechanically, biologically, and chemically

Sludge treatment

Flood and stormwater overflow

Tank purification

Surface drainage

Drainage

 

Benefits:

Choose the best products from a range of pumps in various configurations for all wastewater treatment processes

Extensive international experience providing strong consulting services to planners, equipment manufacturers, and operators

Reliable and efficient operation with non-clogging impellers and energy-efficient drives

Reliable international supplier of pumps, valves, and services

Service and spare parts solutions covering the entire lifecycle

 

 

 

Continuing Carbon Verification Activities

 

Against the backdrop of global efforts to address climate change and promote green development, my country's "Dual Carbon" strategy has become an important guide for the comprehensive green transformation of economic and social development. Shanghai KSB Pump Co., Ltd., with its keen insight into current trends, has proactively responded and implemented measures. In 2021, the company invited the China Quality Certification Center to initiate third-party carbon verification work in accordance with the ISO14064 standard. By verifying and analyzing energy consumption data, we identify energy-saving and consumption-reduction sources and effectively reduce CO2 emissions by reducing energy consumption.

 

In its carbon emissions verification work, Shanghai KSB Pump Co., Ltd. adheres to a scientific and rigorous approach, conducting in-depth investigations and precise calculations of every carbon emission source throughout its production and operations, in accordance with the internationally recognized ISO14064 standard and specifications. The verification covers Scope 1 direct emissions, Scope 2 indirect emissions from purchased energy, and Scope 3 indirect emissions from the transportation system and the use of products. Verification activities encompass all stages, from raw material procurement and production and processing to product transportation. Through years of meticulous verification, Shanghai KSB Pump Co., Ltd. has established a complete and accurate carbon emissions data system, providing solid data support for the development of scientifically sound emission reduction measures and promoting and achieving annual emission reduction targets.

 

In 2024, Shanghai KSB Pump Co., Ltd., building on its carbon verification efforts, expanded its product carbon footprint verification to address the growing customer awareness of energy conservation and environmental protection, as well as the international market's demand for product carbon emissions. During the accounting process, the team conducted an in-depth analysis of carbon emissions from raw material procurement, including emissions from raw material use and energy consumption during transportation. They fully considered the carbon emission intensity of different transportation modes (road, rail, sea, etc.) and the impact of transportation distance on carbon emissions. During the manufacturing phase, detailed statistics were compiled on greenhouse gas emissions from energy consumption of production and testing equipment.

 

Through the team's tireless efforts, they successfully completed the carbon footprint accounting for the ETB 125-100-315 and ETB 100-080-315 products and obtained product carbon footprint certificates from the China Quality Certification Center.

 

This product carbon footprint accounting has yielded significant results for the company. Firstly, it provides a clearer understanding of the carbon emissions of the two products, identifying the main sources and key links in the manufacturing process, and charting the course for subsequent energy conservation and emission reduction efforts. Secondly, this initiative demonstrates the company's commitment to actively implementing the concept of green development and will help enhance its brand image and market competitiveness. Completing the carbon footprint accounting for these two products is just the beginning of Shanghai KSB Pump Co., Ltd.'s green development journey. Going forward, the company will use these two products as a breakthrough point to gradually expand the scope of its product carbon footprint accounting and promote the development and production of more green products. Furthermore, based on the results of the accounting, the company will develop practical emission reduction measures. Through technological innovation, process optimization, and energy structure adjustments, the company aims to reduce product carbon emissions and provide customers with more low-carbon, environmentally friendly products.

 

Benchmarking against green factories and continuously implementing green emission reduction efforts

 

As the concept of sustainable development becomes increasingly popular, green transformation in the industrial sector has become a major trend. As a leader in the industry, Shanghai KSB Pump Co., Ltd. has actively responded to this call and is fully committed to achieving green factory standards by 2025, aiming to build a resource-efficient, environmentally friendly modern factory.

 

In the process of building a green factory, Shanghai KSB Pump Co., Ltd. attaches great importance to energy management. Through a series of technological transformations and management optimizations, it has successfully passed energy management system certification.

 

This certification is not only a recognition of Shanghai KSB Pump Co., Ltd.'s energy management efforts, but also a significant milestone in its journey towards green development. Under the guidance of its energy management system, Shanghai KSB Pump Co., Ltd. meticulously streamlined and optimized its production processes, conducting comprehensive energy-saving assessments and improvements across equipment selection, production processes, and energy procurement. Shanghai KSB Pump Co., Ltd. also introduced an advanced energy monitoring system to monitor energy consumption in real time, promptly identifying and addressing energy waste.

 

To further reduce carbon emissions and achieve green development, Shanghai KSB Pump Co., Ltd. has invested heavily in green energy applications. As early as 2021, the company achieved a 50% reduction in water consumption through the renovation of its water supply and drainage network. The first phase of its rooftop photovoltaic system was installed and connected to the grid in September 2023, and the second phase was completed in October 2024. Together, the two rooftop photovoltaic systems will generate over 6 million kWh annually, meeting over 50% of the factory's electricity needs and reducing carbon emissions by 2,000 tons annually. By the end of 2024, the company's carbon emissions reduction from electricity, water, and natural gas consumption had decreased by 52% compared to 2018. The company achieved the KSB Group headquarters' goal of a 30% year-on-year reduction in carbon emissions by 2025 compared to 2018, ahead of schedule.

 

In production, the company continuously optimizes processes, improves energy efficiency, and reduces carbon emissions at the source. It also strengthens supply chain management, encourages suppliers to embrace green development, and builds a green supply chain to ensure low-carbon processes in raw material procurement and product transportation. The company will also actively participate in industry exchanges and collaborations, share its experience in establishing green factories, and contribute to the green development of the entire pump industry, leading the industry towards a more environmentally friendly and sustainable future.

 

 

Future Outlook

 

Shanghai KSB Pump Co., Ltd. will continue to unwaveringly advance its green and sustainable development strategy, incorporate zero-carbon factories into its corporate development strategy, and continuously strengthen carbon emission management and control. The company will further increase investment in clean energy utilization, production process innovation, and green supply chain integration, continuously exploring new emission reduction technologies and methods, and strive to achieve even higher emission reduction targets. The company will actively participate in carbon emission-related activities within the industry and society, strengthen cooperation and exchanges with governments, research institutions, and businesses, and jointly promote solutions to global climate change and contribute more to building a beautiful home for our planet.

What are the key terms of centrifugal pump?

 

1. Working point: the point on the performance curve that represents the actual running condition of the centrifugal pump is the intersection of the head curve and the resistance curve.

 

2. Specified point: the point determined by the specified flow rate and the specified head on the performance curve.

 

3. Head rise: the algebraic difference between the total water head at the outlet and the total water head at the inlet.

 

4. Close Yangcheng: the total head when the pump flow is zero.

 

5. Specified head: the total head corresponding to the specified flow rate on the contract sheet.

 

6. Cavitation margin: The difference between the absolute total water head at the inlet relative to the NPSH reference plane and the vaporization pressure head.

 

7. Allow suction vacuum height: For different types of pumps and different operating conditions, consider a certain safety margin of suction vacuum height.

 

8. Rated flow: the flow rate at the guaranteed point.

 

9. Pump output power: the power transferred to the output liquid by the pump.

 

10. Pump input power (shaft power): the power transmitted from the drive machine to the pump.

 

11. Drive input power: the power absorbed by the pump drive.

 

What are the wrong ways to use a pump?

 

As a key component for water transportation and pressure boosting, pumps play a vital role in water supply systems. However, they frequently encounter operational issues, most of which stem from improper usage. Years of practical experience have identified ten common misuse patterns in pump operation.

 

1.Overload

 

 

Whether it is flow, pressure or speed, long-term excessive deviation from the rated design point of work, may lead to increased pump load, such as centrifugal pump full open power maximum, shorten its life, or even "death".

 

2. Difficulty in medium inhalation

 

● The imported liquid level is too low, which is easy to produce vortex, suck in air, resulting in cavitation, flow head reduction;

● The inlet pipe or inlet is blocked by foreign matter, resulting in reduced flow and head;

● When the medium temperature increases, the vaporization pressure of the medium increases, and the cavitation margin decreases, resulting in the decrease of the suction stroke;

● The inlet pipe is unreasonable (such as: too many elbow joints of the inlet pipe, the pipe diameter is smaller than the pump inlet), the pipeline loss increases, and the cavitation margin decreases, which is easy to cause cavitation;

● The installation altitude of the pump is increased, the atmospheric pressure is reduced, the cavitation margin is reduced, resulting in the suction stroke is reduced.

 

3. Close the valve only, and the water pump is not powered off

 

In addition to automatic pumps and intelligent pumps, ordinary water pumps are operated for a long time under closed valve conditions, and there is no bypass. All the energy consumption of the system is wasted in "heating" water, resulting in pump cavitation, which causes unstable operation of the pump and even accidents.

 

4. CORROSION

 

The conveyed medium may corrode flow components and mechanical seals. For example, hydrochloric acid corrodes stainless steel, and hydrofluoric acid corrodes silicon carbide.

 

Note: The corroded surface will appear with a dense array of pinholes of varying sizes, resembling the surface of the moon.

 

 

 

5. Erosion

 

The liquid carrying solid particles will continuously wash the pump chamber, impeller and other flow components, so that the pump's service flow, head and life are reduced.

 

Note: In case of severe abrasion, fish scale pattern will appear on the abraded surface.

 

 

 

 

6. Pump body cracking

 

Due to the blockage of export or the high pressure of import, or the freezing of liquid in the pump chamber due to low temperature, the actual pressure of the pump chamber is far higher than its bearing pressure, and finally the pump body cracks.

 

7、vibrate

 

The pump is installed on a rigid foundation, lacking vibration damping measures, or the foundation is too weak to provide sufficient strength. The inlet and outlet pipelines lack support, resulting in uneven force on the unit, which binds the pump's operating vibration, and the pump "jumps" like on a trampoline.

 

8. Dampness

 

● The onshore pump is in a wet environment for a long time or the mechanical seal fails, and the liquid leakage splashes to the motor's non-sealed part.

●  The sealing of the submersible pump is failed, the cable is not sealed, the pump is exposed to moisture in the humid environment or the cable is dropped into the pool, resulting in liquid intrusion into the motor chamber.

 

Note: If there are water stains and condensate beads in the motor and the insulation resistance is less than 50 megohms, it is considered to be damp.

 

9. Irregular inspections

 

Pumps never get enough "care". They are not checked and maintained regularly according to the instructions, the machine seal is not replaced irregularly, the iron pump and aluminum pump are not repainted, and the vibration is not checked, so that the pump from "minor disease not treated" to "major disease not treated".

 

10. Poor heat dissipation

 

 

● The submersible electric pump motor is exposed to the water surface for dehydration operation, or sunk in the mud, so that the motor heat dissipation is slow, easy to cause burning, especially the oil-filled motor heat dissipation is bad, there is a chance of explosion.

●  The onshore pump is installed in the corner or in the closed box, and the fan cannot ventilate the surrounding air, resulting in poor heat dissipation of the motor.

 

XYLEM serves the top sewage treatment plants in Asia

As the largest sewage treatment plant in Asia, Shanghai Zhuyuan Sewage Treatment Plant covers an area of 33.79 hectares, with a total treatment capacity of 3.4 million tons per day, serving a population of 6 million. It ranks among the first batch of green and low-carbon benchmark sewage treatment plants, providing ecological and environmental protection for the sustainable development of Shanghai.

 

Sailor's flagship wastewater treatment system, featuring UV filtration, sedimentation tanks, and pump-aeration technology, has enabled Shanghai Zhuyuan Wastewater Treatment Plant to achieve' volume reduction and capacity upgrade'. This innovation has reduced CO₂ emissions by 16,400 tons, generating annual economic benefits of approximately 13 million yuan, while ensuring operational excellence and sustainable development.

 

UV System

 

 

WEDECO Duron UV System

♦ The total UV treatment capacity reaches 2.6 million tons per day (cumulative from Zhuyuan Plant 1, 2, and 4)

♦ Unique 45-degree slanted fabric lamp with enhanced sterilization effect

♦ ECORAY's lamp tubes and advanced rectifier technology reduce operating costs

 

Filter system

 

 

 

Leopold denitrification deep bed filter

♦ China's largest single-phase denitrification filter project, with a daily processing capacity of 1.1 million tons

♦ Ultra-long running cycle and ultra-low backwash water consumption

♦ Ensure Class 1A effluent quality at high filtration rates

 

Pump and Suction System

 

 

Flygt Flying Submarine Pump, Custom High-Flow Pump

(PL Series Axial Flow Pumps, N Series Submersible Pumps)

♦ World leader in submersible pump innovation

♦ Continuous and efficient, no clogging

♦ Easy installation and smart control

♦ Meet all pumping needs of sewage treatment plant

 

B&G GLC Series Vertical Pipeline Pump

♦ Ultra high pump efficiency and ultra low cavitation margin

♦ Compact structure, stable and reliable

 

 

 

 

Lowara e-SV Vertical Multi-stage Pump

♦ High efficiency achieved by sophisticated hydraulic model

 

 

Regarding some questions about screw pumps, Anhui Shengshi Datang would like to share some insights with everyone.

  Causes and Hazards Analysis of Rod String Reverse Rotation in Screw Pump Wells

1. Analysis of Causes for Rod String Reverse Rotation in Screw Pump Wells

During oilfield extraction using Screw Pumps, reverse rotation of the rod string is a relatively common failure. The causes of this reverse rotation are complex, but the primary reason is the sudden shutdown or sticking of the pump during operation, which causes deformation and torsion of the rod string. The rapid release of this deformation and torsion then leads to reverse rotation. Specifically, if the Screw Pump suddenly stops or sticks during operation, a pressure difference arises between the high-pressure liquid retained in the production tubing and the wellbore hydrostatic pressure in the casing annulus. Driven by this pressure difference, the Screw Pump acts as a hydraulic motor, driving the rotor and the connected rod string to rotate rapidly in reverse.

The reverse rotation of the Screw Pump rod string is influenced by the tubing-casing pressure difference, exhibiting variations in reverse rotation duration and speed. Generally, a larger tubing-casing pressure difference results in faster reverse rotation speed and longer duration for the rod string. As the pressure difference gradually decreases, the reverse rotation speed and duration correspondingly decrease until the pressure difference balances, at which point the reverse rotation gradually ceases. When reverse rotation occurs, the rod string vibrates intensely. If resonance occurs during this vibration—meaning the vibration frequency of the reversing rod string synchronizes with the natural frequency of the wellhead—the rotation speed can instantly surge to its maximum. This situation can trigger serious safety accidents, cause significant harm to the worksite, and even result in casualties.

2. Hazards of Rod String Reverse Rotation in Screw Pump Wells

The hazards caused by rod string reverse rotation vary in degree depending on the speed and duration of the reversal. Severe cases can lead to onsite safety incidents with serious consequences. Specifically, the hazards mainly manifest in the following three aspects:

(1) Reverse rotation can cause the rod string to become displaced from its original position, leading to the swinging of the Screw Pump polish rod. This can cause significant wear and tear on the Screw Pump equipment, damaging various components and parts.

(2) During reverse rotation, if the speed is too high or the duration too long, the temperature of the reversing components can continuously rise, potentially igniting flammable gases at the wellhead. This could trigger an explosion at the worksite, leading to unforeseeable serious consequences.

(3) If reverse rotation is not effectively controlled, it can cause the drive pulley to shatter. Fragments of the pulley flying around the worksite pose a risk of injury to personnel, damage the oilfield production site, reduce extraction efficiency, and increase the probability of various safety incidents.

  Commonly Used Anti-Reverse Rotation Devices for Screw Pump Well Rod Strings

1. Ratchet and Pawl Type Anti-Reverse Device

This type of device prevents reverse rotation by utilizing the one-way engagement of a ratchet and pawl. Specifically, the ratchet and pawl engage via an external meshing configuration. When the Screw Pump drive operates normally, centrifugal force causes the pawl to disengage from the ratchet brake band, so the anti-reverse device remains inactive. However, when the Screw Pump suddenly stops during operation, the rod string begins to reverse due to inertia. During this reverse rotation, gravity and spring force cause the pawl to engage with the ratchet brake band, activating the anti-reverse device. The device then dissipates the torque generated by the high-speed reverse rotation through frictional force.

The ratchet and pawl device has a simple structure, is easy to install, has a low overall cost, and offers good flexibility and controllability. However, it typically requires manual intervention at close range for activation/operation. Improper operation can cause the friction surfaces to slip, presenting a safety risk. Additionally, this type of device can generate significant noise during operation and subjects the components to considerable impact and wear, necessitating frequent part replacements.

2. Friction Type Anti-Reverse Device

The friction type anti-reverse device consists of two main parts: an overrunning clutch that identifies rotation direction and a brake shoe assembly. In this device, the brake shoes are connected to the brake bodies via riveting, and the two brake bodies grip the outer ring. During normal Screw Pump operation (clockwise rotation), the device remains inactive. When a sudden shutdown causes reverse rotation, the drive mechanism reverses. In this state, rollers move between the star wheel and the outer ring, activating the device. The resulting damping effect restricts the rotation of the star wheel, thereby achieving the anti-reverse function. However, since the operation of this device often requires manual control, improper handling can lead to failure. Furthermore, replacing this device involves significant safety risks. Consequently, its application in Screw Pump wells is currently relatively limited.

3. Sprag Type Anti-Reverse Device

The sprag type anti-reverse device operates based on the principle of an overrunning clutch. Specifically, during normal Screw Pump operation (forward rod string rotation), the sprags inside the device align normally and remain disengaged from the outer ring, keeping the device inactive. When the pump suddenly stops and the rod string starts to reverse rotate, the resulting reverse torque causes the device to rotate in the opposite direction. This makes the sprags align in the reverse direction, locking them against the outer ring and preventing reverse rotation of the rod string.

The sprag type device has a simple construction, is easy to install, offers good controllability, and operates with high safety, minimizing the risk of accidents. It also has a long service life and does not require frequent part replacements. The drawback is that it cannot fundamentally solve the reverse rotation problem. If the reverse torque exceeds the capacity the sprags can withstand, it can cause sprag failure and device malfunction. Additionally, daily maintenance of this device can be inconvenient.

4. Hydraulic Type Anti-Reverse Device

The working principle of the hydraulic anti-reverse device is somewhat similar to a car's braking system. When the Screw Pump suddenly stops and the rod string is about to reverse rotate, the hydraulic motor within the device activates. Hydraulic fluid pressure drives friction pads against a brake disc, releasing a large amount of the reverse rotation potential energy, thereby dissipating the reverse rotation of the rod string.

The advantages of the hydraulic type device include stable and reliable operation, high safety, no noise generation, and no hazard to onsite personnel. Maintenance, replacement, and daily upkeep are relatively convenient and safe. This type of device can more thoroughly address the reverse rotation problem, enhancing the operational safety of the Screw Pump system. The disadvantages are its high overall cost and stringent quality requirements for the hydraulic components, leading to potentially higher maintenance and replacement costs. If issues like hydraulic fluid degradation or leaks occur during operation, the device's performance can be affected, necessitating regular maintenance.

  Measures to Address Rod String Reverse Rotation in Screw Pump Wells

1. Research and Application of Safer, More Reliable Anti-Reverse Devices

Analysis of the causes of rod string reverse rotation indicates that the main factors are the release of stored elastic potential energy in the rod string and the effect of the tubing-casing pressure difference. If reverse rotation is not effectively controlled, especially at high speeds or for prolonged durations, it can lead to a series of severe consequences and safety incidents, posing significant risks. Therefore, technical research and application should be strengthened. Based on existing anti-reverse devices, upgrades and improvements should be made to develop and apply safer and more reliable devices. These should ensure the safe release of torque and effective elimination of the pressure difference during sudden Screw Pump shutdowns, reducing associated safety risks. The working principles, advantages, and disadvantages of common anti-reverse devices need in-depth analysis for targeted improvements. This will enhance the stability and reliability of these devices, minimize safety risks during use, and maximize the operational safety of Screw Pump equipment.

2. Application of Downhole Anti-Backflow Switches

Using downhole anti-backflow switches can effectively address reverse rotation caused by hydraulic forces. The downhole anti-backflow switch consists of components like a disc, ball, push rod, shear pin, and crossover sub. Its application in the Screw Pump drive system can reduce the torque generated during sudden shutdowns, lower the reverse rotation speed, and mitigate reverse rotation caused by the tubing-casing pressure difference. By dissipating hydraulic forces, it helps control reverse rotation and also prevents rod string back-off. The anti-backflow switch has a simple structure, low cost, and is easy to install. It has been widely used in oilfield development due to its strong stability, high reliability, and broad application prospects.

3. Strengthening Surface Safety Management

To effectively control reverse rotation, it is essential not only to equip Screw Pump systems with appropriate anti-reverse devices but also to enhance safety management in surface operations and implement protective measures to reduce the adverse consequences of reverse rotation. Specific measures include:

① Personnel should perform daily inspection, maintenance, and servicing of Screw Pump equipment, maintain proper equipment management records, continuously accumulate experience, and improve safety prevention capabilities.

② Implement continuous monitoring of the Screw Pump system's operation to promptly detect abnormalities. Take immediate action for fault diagnosis and troubleshooting to reduce the probability of reverse rotation occurrences.

③ Establish comprehensive emergency response plans. For sudden reverse rotation events, immediately activate the emergency plan to lower the probability of safety incidents.

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.