A spectrophotometer is a scientific instrument that quantifies the amount of light absorbed or transmitted by a solution at any specific wavelength. Spectrophotometers are used for qualitative and quantitative analysis of chemical materials. Spectrophotometers are also commonly used in laboratories and research settings in fields such as chemistry, biology, physics, and materials science.

They are used for a range of activities, including enzyme activity, DNA/RNA quantification, color analysis, and quality control in manufacturing. Modern spectrophotometers can measure across multiple ranges of the electromagnetic spectrum (ultraviolet, visible, infrared), depending on the analysis being performed.

1.The Concept of Portable Spectrophotometers

A portable spectrophotometer is a small, handheld tool used to measure the absorption or reflectance of light to characterize the optical properties of samples outside the laboratory. It is also based on the same fundamental science as large benchtop spectrophotometers, primarily on the Beer-Lambert law.

1.1 Advantages and Limitations of Portable Spectrophotometers

Portable spectrophotometers offer advantages such as portability, on-site analysis capabilities, and user usability, making them suitable for fieldwork, quality assurance, and faster decision-making.

Advantages:

Portability—Small size and light weight allow for movement and use in factories and anywhere else you have quality issues, including in the field.

On-site Measurement—Measure in the field or online, eliminating the need to send samples to a laboratory.

Speed—Sometimes provides rapid results within seconds, facilitating quick decisions in high-risk situations such as forensic science or customs clearance.

Ease of Use: Typically designed for non-professional users and ease of use, intuitive even for non-technical users.

Non-destructive Testing: Enables non-contact measurements without damaging the sample when testing through packaging such as plastic and glass.

Limitations:

Accuracy and Sensitivity: The accuracy and sensitivity of the sensor may not match those of high-end stationary models.

Wavelength Range: The spectral range of many instruments is narrowed to enable accurate analysis.

Environment: Sensor performance can be affected by external forces such as temperature and light.

Sample Contamination: Sample contamination is more likely than in field applications.

Quantification: In some field applications, quantifying results can still be a challenging process.

2.The Concept of Benchtop Spectrophotometers

Benchtop spectrophotometers are stationary precision laboratory instruments used to measure the interaction between samples and light. Designed to deliver the most accurate measurements, they serve as exceptional tools for laboratory analysis, quality control, and color formulation across industries.

Spectrophotometers operate based on the Beer-Lambert Law, which states that the absorbance of light by certain substances is directly proportional to the concentration of the substance and the path length of light passing through the sample.

2.1 Advantages and Limitations of Benchtop Spectrophotometers

Benchtop spectrophotometers offer advantages such as precision, consistency, and broad flexibility for in-depth color and spectral analysis in stable laboratory environments, though they are less portable, more expensive, and require a controlled lab setting.

Advantages:

Precise Accuracy and Consistency: Benchtop versions deliver superior accuracy and stability. Consistent results are critical for working within tighter tolerances and achieving precise color matching.

Flexibility: Benchtop spectrophotometers can measure diverse samples, including solids, liquids, and powders. Most models offer multiple measurement modes (e.g., transmittance and reflectance) as standard.

Advanced Features: Many benchtop spectrophotometers now include useful functions such as adjustable apertures and additional viewing angles. Some quality control spectrophotometers can even analyze defects like haze, and some include backstops to minimize errors.

Data Analysis: Data from benchtop spectrophotometers can also be sent to a computer for analysis. If integrated into a Laboratory Information Management System (LIMS), this may include report generation or data analysis.

Limitations:

Non-portable—They are bulky and heavy. Due to their size, they remain plugged into a fixed location and cannot be used for field or on-site measurements.

Expensive—Benchtop spectrophotometers are typically significantly more costly than portable spectrophotometers, primarily because benchtop models are often more complex and/or feature more advanced optics or instrumentation.

Requires Controlled Environment—Desktop units must be set up and operated in a laboratory setting, which may not be feasible for all intended applications.

Operator Skill Requirements—Operating and interpreting results from a desktop spectrophotometer necessitates specialized knowledge and an understanding of the science behind spectrophotometric applications.

Differences Between Portable Spectrophotometers and Benchtop Spectrophotometers

Conclusion: Portable Spectrophotometers vs. Benchtop Spectrophotometers

Choosing between a portable spectrophotometer and a benchtop spectrophotometer depends on the tasks you will be performing. If you need to conduct on-site inspections, perform minute measurements, and/or frequently move the instrument, the portability and accessibility of a portable spectrophotometer may be your best option. If you require extremely high precision for research and measurement, perform spectral analysis, or operate in a laboratory setting, a benchtop spectrophotometer is the instrument better suited to meet your needs.

Email: hello@utstesters.com

Direct: + 86 152 6060 5085

Tel: +86-596-7686689

Web: www.utstesters.com

Combined temperature and humidity cycling test is to expose the samples to the set temperature and humidity alternating test environment, to evaluate the samples through the temperature, humidity environment cycling or storage of the functional characteristics of the changes.

The environment in which the product is stored and worked in has a certain temperature and humidity, and it will change constantly. For example, the temperature difference between day and night, different humidity at different temperatures and different times, and different temperature and humidity areas during the transport of products. This alternating temperature and humidity environment will affect the performance and life of the product and accelerate the aging of the product. The temperature and humidity cycle simulates the temperature and humidity environment in which the products are stored and worked, and checks whether the products are affected in this environment for a period of time within an acceptable range.

It is used to test the quality of mobile phones, plastic products, metals, food, chemicals, building materials, medical, aerospace and other products.

Temperature and humidity test chamber mainly for constant temperature and humidity test and temperature and humidity cycle test

1. Constant temperature and humidity test

Test purpose: to assess the adaptability of products for use and storage under hot and humid conditions, observe the impact of test samples at constant temperature, no condensation, high humidity environment for a specified period of time, in order to accelerate the evaluation of the test samples to resist the effect of hot and humid deterioration.

Test equipment: constant temperature and humidity chamber

Test conditions: test temperature; test humidity; test time.

Commonly used preferred temperature/humidity: 40℃, 85%; 40℃, 93%; 85℃, 85%, etc.; commonly used

preferred test time: 48h, 96h, etc.

2. Temperature and humidity cycling test

Test Purpose: Applicable to determine the suitability of the test specimen for use and storage under hot and humid conditions of temperature cycling changes and surface condensation.

Test conditions: Selection of temperature, humidity, number of cycles, rate of temperature change and duration.

Temperature and humidity cycle main effects:

1. Expansion of the material by water intake

2. Loss of physical strength

3. Change in chemical properties

4. Degradation of insulation properties

5. Corrosion of machine parts and failure of lubricants.

6. Oxidation of materials

7. Loss of plasticity

8. Acceleration of chemical reactions

9. Degradation of electronic components

Method Standard

Temperature and Humidity Cycling Test Standard Reference: GB/T 2423.34, IEC 60068-2-38, EN 60068-2-38, etc.

Email: hello@utstesters.com

Direct: + 86 152 6060 5085

Tel: +86-596-7686689

Web: www.utstesters.com

Testing fabric color fastness with gray cards is a fundamental and crucial evaluation method in the textile industry. It primarily serves to objectively assess the degree of color change in textiles after undergoing tests such as rubbing, washing, perspiration exposure, and light exposure, as well as the potential for color transfer to adjacent fabrics.

1. What is Fabric Color Fastness?

Colored fabrics during production or garments made from them during use are subjected to various external environmental factors. The ability to resist these external forces is termed the colorfastness property of the fabric or garment.

2. What is Fabric Discoloration?

In dyed textiles, environmental factors can cause fiber color loss, destruction of dye chromophores, or generation of new chromophores. This leads to changes in color saturation, hue, and brightness.

3. What is fabric color migration?

This refers to the phenomenon where, under various environmental influences, dyes detach from the originally coated fibers and transfer to other fabrics, causing them to become stained.

During colorfastness gray scale grading, discoloration and migration gray scales are used to evaluate colorfastness. Currently used gray scales include AATCC, ISO, JIS, and Chinese National Standard GB gray scales. Each gray scale has slightly different gray levels.

4.How to Use Gray Scales to Test Fabric Color Fastness

4.1 Discoloration Gray Scale: Used to evaluate changes in the test sample's own color. It consists of 5 pairs of small gray cards, ranging from Level 5 to Level 1.

Level 5 indicates no change at all, while Level 1 indicates the most severe change. Within each pair, the left card is a fixed neutral gray, and the right card gradually lightens in shade, representing the degree of color change.

4.2 Dye Transfer Gray Cards: Used to evaluate the degree of color transfer from the test sample to an adjacent white fabric (commonly called the backing fabric). Consists of 5 pairs of small white and gray cards, ranging from Level 5 to Level 1.

Level 5 indicates no color transfer whatsoever, while Level 1 indicates the most severe color transfer. In each pair, the left card is a fixed white, and the right card is a progressively darker gray, representing the degree of color transfer.

5. Color Fastness Gray Scale Evaluation Method

Grading Scale Table

Masking Card

(As shown above), during grading, specially designed apertures are used to mask sample cards for evaluating multi-fiber fabric staining, rubbing colorfastness staining, and general staining assessment.

Using masking cards allows better focus on the sample being graded while covering other areas to prevent visual interference.

6. Grading Environment

6.1 Light Source

We commonly use the D65 light source. The bulb lifespan is 2000 hours. Other light sources may be specified, such as F light source, 84-P light source, UV light source, etc.

6.2 Darkroom Lighting

Darkroom: The grading process must be conducted in a darkroom with constant humidity and temperature. Additionally, the walls and furnishings of the darkroom must be painted in a neutral gray shade, approximately matching the level between Grade 1 and Grade 2 on the gray scale (roughly equivalent to Munsell N5). As shown in the image above, the left side displays the neutral gray of the walls with the lights on, while the right side shows the color after the lights are turned off. The entire darkroom must be free of any light sources other than the light source from the grading lightbox. Furthermore, no other objects should be present on the grading table.

7. Observer's Line of Sight

Grading Angle

Grading samples using gray cards requires precise angles! This standard mandates:

- Sample positioned at 45° to the horizontal plane

- Grading light source at 45° to the sample

- Observer's eyes at 90° to the sample

Observer-to-sample distance: 50-70 cm.

8. Precautions for Viewing Color Fastness Evaluation Cabinets

8.1 Light Source is Critical: Grading must never be conducted under everyday indoor lighting (e.g., incandescent or fluorescent lamps), as results will be severely distorted.

8.2 Viewing Angle: During observation, the sample and gray card should be placed on the same plane, with the line of sight forming approximately a 45° angle to the sample surface.

8.3 Multiple-Rater Grading: For greater objectivity, two or more graders should independently evaluate samples, then average the ratings. If discrepancies exceed 0.5 grades, a third grader must re-evaluate or consensus must be reached through discussion.

Gray Scale Maintenance: Gray scales are precision instruments. Avoid soiling, scratching, and light exposure. Store in protective sleeves after use.

Gray scale grading represents the final presentation of colorfastness test results and constitutes the concluding step in colorfastness testing. Regardless of prior process accuracy and standardization, grading errors can invalidate the entire test. Grading remains a challenging task. Ensuring consistency among personnel within the same laboratory is crucial, as is maintaining consistency between testing institutions. As more brands collaborate with multiple laboratories, inter-laboratory consistency becomes increasingly vital.

Email: hello@utstesters.com

Direct: + 86 152 6060 5085

Tel: +86-596-7686689

Web: www.utstesters.com

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.

Email: hello@utstesters.com

Direct: + 86 152 6060 5085

Tel: +86-596-7686689

Web: www.utstesters.com

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%

Email: hello@utstesters.com

Direct: + 86 152 6060 5085

Tel: +86-596-7686689

Web: www.utstesters.com

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:

Email: hello@utstesters.com

Direct: + 86 152 6060 5085

Tel: +86-596-7686689

Web: www.utstesters.com

An EV charger is a long-term investment for electric vehicle owners and operators—but its lifespan depends heavily on regular maintenance. Skipping simple upkeep can lead to frequent breakdowns, slower charging, or even safety risks. Below are the most actionable steps to keep your charger running reliably for years.​

Regular Cleaning: Stop Damage Before It Starts​

External Cleaning​

Dust, rain residue, or spilled liquids (like garage cleaners) build up on your charger over time, seeping into ports or corroding casings. After each use, wipe the exterior and cable with a dry, lint-free cloth. For sticky stains, use a damp cloth with mild soap—avoid harsh chemicals that harm insulation. Check the charging port weekly with a soft brush to clear debris; blocked ports cause overheating.​

Internal Cleaning​

Internal dust can short-circuit components, but never open the charger yourself. For home or commercial units (like those in an operating charging station), hire a certified technician to blow out dust with compressed air once a year—this is especially critical for high-use models.​

Electrical System Checks: Catch Issues Early​

Voltage and Current Monitoring​

Fluctuations in power damage chargers over time. For a 7KW home charger, use a basic voltage tester monthly to ensure it’s receiving stable power (120V/240V, depending on your setup). At operating charging stations, invest in smart monitoring tools to track current—spikes often signal wiring issues that need immediate fixes.​

Circuit Inspection​

Check the charger’s plug, outlet, and internal wiring (via a technician) every 3–6 months. Look for loose connections or discolored plugs—these are signs of overheating that can ruin the charger.​

Thermal Management: Prevent Overheating​

Overheating is the top cause of AC charger failure. Keep your charger in a shaded, well-ventilated area (avoid direct sunlight or enclosed spaces). For outdoor units, install a waterproof cover with vents. Every 2 months, clean the charger’s 散热 grilles with a dry brush to remove dust—blocked grilles trap heat.​

Quick Habits: Handle and Store Wisely​

Never yank the charging cable—pull by the plug to avoid fraying wires.​

When not in use, coil the cable loosely (don’t twist it) to prevent internal damage.​

For seasonal storage (e.g., winter garages), keep the charger in a dry area above 0°C to avoid freezing damage.​

Simple, consistent maintenance—cleaning, electrical checks, and careful handling—will double your EV charger’s lifespan. By following these steps, you avoid costly repairs and ensure your charger (whether a 7KW home model or an AC charger at an operating charging station) stays reliable for years.

Reliability and efficiency are critical for EV chargers, especially in high-traffic public and commercial environments where uptime directly impacts both user satisfaction and business operations. As a high quality EV charger manufacturer, USTEU designs its products to operate continuously, delivering consistent performance without interruptions. For drivers, reliable chargers mean they can plug in their vehicles anytime—day or night—without worrying about malfunctions or delays, ensuring a smooth and convenient charging experience.

Efficiency also plays a vital role in these scenarios. In busy locations such as shopping centers, office buildings, hotels, and highway service stations, chargers must manage energy precisely to serve multiple users quickly while minimizing downtime. USTEU systems provide high-power output with intelligent energy management, allowing operators to serve more vehicles simultaneously and maintain steady charging speeds. This efficiency reduces waiting times for drivers and helps businesses maximize throughput, operational capacity, and customer satisfaction.

Furthermore, USTEU integrates smart technologies to enhance both reliability and efficiency. As a provider of smart electric vehicle charging stations, USTEU chargers feature real-time monitoring, automated protection mechanisms, and intuitive interfaces. These features prevent faults before they occur, ensure optimal energy usage, and allow operators to monitor and manage their stations remotely. For commercial operators offering fast DC charging solutions for business, these capabilities are essential to maintain a competitive edge, as rapid and dependable charging attracts more customers and keeps fleet operations running smoothly.

In addition to technology, USTEU emphasizes durable construction and high-quality materials, ensuring that every charger withstands continuous operation in diverse environmental conditions. This combination of robust engineering, intelligent design, and efficient power management guarantees that USTEU chargers can run reliably around the clock, providing drivers with the convenience they expect and operators with the operational confidence they need.

In summary, reliability and efficiency are key because they directly affect user experience, business performance, and long-term operational sustainability. By offering durable, high-performance chargers equipped with smart management features, USTEU ensures that both everyday drivers and commercial operators can depend on their EV charging infrastructure to operate efficiently, safely, and consistently at all times.

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.

Working Principle of Centrifugal Pumps

The working principle of centrifugal pumps is based on the action of centrifugal force. When the impeller rotates at high speed, the liquid is thrown from the center of the impeller to the outer edge under the influence of centrifugal force, thereby gaining kinetic energy and pressure energy. The specific working process is as follows:

1.Liquid enters the central area of the impeller through the pump's suction inlet.

2.The rotation of the impeller generates centrifugal force, causing the liquid to move from the center of the impeller to the outer edge along the blade passages.

3.The liquid gains kinetic energy and pressure energy within the impeller and is then discharged into the pump casing.

4.Inside the pump casing, part of the liquid's kinetic energy is converted into pressure energy, and the liquid is ultimately discharged through the outlet.

During the operation of a centrifugal pump, the impeller does work by converting mechanical energy into the energy of the liquid. As the liquid flows through the impeller, both its pressure and velocity increase. According to Bernoulli's equation, the increase in the total energy of the liquid is primarily manifested as an increase in pressure energy, enabling the centrifugal pump to transport the liquid to a higher elevation or overcome greater system resistance.

It is important to note that the prerequisite for the normal operation of a centrifugal pump is that the pump cavity must be filled with liquid. This is because centrifugal force can only act on liquids and not on gases. If air is present in the pump cavity, the pump will be unable to build up pressure normally, resulting in "vapor lock," which ultimately leads to cavitation.

Analysis of Causes for Centrifugal Pump Cavitation

 1.Inadequate Inlet Medium or Insufficient Inlet Pressure

Inadequate inlet medium is one of the most common causes of centrifugal pump cavitation. The following situations may lead to insufficient inlet medium:

a. Low Liquid Level: When the liquid level in a pool, tank, or storage container falls below the pump's suction pipe or the minimum effective level, the pump may draw in air instead of liquid, resulting in cavitation.

b. Excessive Suction Lift: For non-self-priming centrifugal pumps, if the installation height exceeds the allowable suction lift, even if the suction pipe is immersed in the liquid, the pump will be unable to draw the liquid up, leading to a lack of liquid inside the pump. According to physical principles, the theoretical maximum suction lift for non-self-priming centrifugal pumps is approximately 10 meters of water column (atmospheric pressure value). However, considering various losses, the actual suction lift is typically below 6-7 meters.

c. Insufficient Inlet Pressure: In applications requiring positive inlet pressure, if the provided inlet pressure is lower than the required value, the pump may experience inadequate liquid supply, causing cavitation.

d. Poor System Design: In some system designs, if the suction pipeline is too long, the pipe diameter is too small, or there are too many bends, the pipeline resistance increases, reducing the inlet pressure and preventing the centrifugal pump from drawing liquid properly.

Case studies show that approximately 35% of centrifugal pump failures in the petrochemical industry are caused by inadequate inlet medium or insufficient inlet pressure. This issue is particularly common in oil transportation systems due to the high viscosity and vapor pressure of oil products.

 2.Blockage in the Inlet Pipeline

Blockage in the inlet pipeline is another common cause of centrifugal pump cavitation. Specific manifestations include:

a. Clogged Screens or Filters: During long-term operation, screens or filters in the inlet pipeline may become gradually blocked by impurities or sediments, restricting liquid flow.

b. Scale Formation Inside the Pipeline: Particularly when handling hard water, water with high calcium and magnesium ion content, or specific chemical liquids, scale or crystalline deposits may form on the inner walls of the pipeline, reducing the effective diameter over time.

c. Foreign Object Entry: Accidental entry of objects such as leaves, plastic bags, or aquatic plants into the suction pipeline can block elbows or valves, obstructing liquid flow.

d. Partially Closed Valves: Operational errors, such as failing to fully open valves in the suction pipeline, or internal valve malfunctions, can also lead to insufficient flow.

e. Foot Valve Failure: In systems equipped with foot valves, if the foot valve malfunctions (e.g., spring deformation or sealing surface damage), it can affect the pump's ability to draw liquid properly.

Statistical data indicate that approximately 25% of centrifugal pump cavitation cases in municipal water supply and drainage systems are caused by inlet pipeline blockages. This issue is especially common in wastewater treatment systems with high levels of suspended solids.

 3.Incomplete Air Removal from the Pump Cavity

Incomplete air removal from the pump cavity is a significant cause of centrifugal pump cavitation. Key manifestations include:

a. Inadequate Priming Before Initial Startup: After initial installation or prolonged shutdown, centrifugal pumps must be primed to remove air from the pump body. If priming is insufficient, residual air can prevent the pump from establishing normal working pressure.

b. Insufficient Self-Priming Capability: Non-self-priming centrifugal pumps cannot expel air on their own and rely on external priming. While some self-priming pumps have a certain self-priming capability, improper startup methods or excessive self-priming height can lead to poor air expulsion.

c. Air Leaks in the Pipeline System: Minor cracks in suction pipeline connections, sealing points, or aging pipes can allow air to enter the system under negative pressure. This is particularly hazardous because even if the pump is initially primed correctly, air can accumulate over time, eventually causing cavitation.

d. Seal Failure: Worn or improperly installed shaft seals (e.g., mechanical seals or packing seals) can allow external air to enter the pump, especially when the suction side pressure is below atmospheric pressure.

In industrial applications, approximately 20% of centrifugal pump cavitation cases are caused by incomplete air removal from the pump cavity. This issue is particularly common during initial startup after installation or maintenance.

 4.Other Causes

In addition to the main causes mentioned above, other factors can also lead to centrifugal pump cavitation:

a. Liquid Vaporization: When handling high-temperature or highly volatile liquids, if the suction pipeline pressure falls below the liquid’s saturation vapor pressure at that temperature, the liquid may vaporize, forming bubbles. This can prevent the pump from drawing liquid or cause cavitation.

b. Operational Errors: Human factors, such as incorrect valve operation or failure to follow startup procedures, can lead to pump cavitation.

c. Control System Malfunctions: In automated control systems, failures in level sensors, pressure sensors, or errors in PLC programming logic may cause the pump to start or operate under inappropriate conditions, resulting in cavitation.

d. Power or Motor Issues: Incorrect power phase sequence causing motor reversal can prevent the pump from drawing liquid properly. Voltage instability causing motor speed fluctuations can also disrupt normal pump operation.

e. Temperature Effects: In extreme environmental conditions, such as cold regions, inadequate insulation may cause liquid in the pipeline to freeze, obstructing flow. In high-temperature environments, liquids may vaporize, forming vapor locks.

Research indicates that these other causes account for approximately 20% of centrifugal pump cavitation cases. Although the proportion is relatively small, they can be significant factors in specific scenarios or conditions and should not be overlooked.