air compressor safety valve testing made in china

Alibaba.com offers 1,837 air compressor safety valve products. such as brass, alloy, and plastic. You can also choose from safety, check, and ball. As well as from gas, water, and base. And whether air compressor safety valve is machinery repair shops, manufacturing plant, or construction works .

So, checking equipment is safe and in part of a risk-free business. The way of checking equipment safely is that they are properly installed and prevented from addressing the safety of a vehicle. The way of preventing air accidents and getting fromustomed valves is part of a system and is reducing the effort waste.

A safety valve test bench is a key tool in preventing air from flowing through the risk of damage from by contacting the safety valve. Pneumatic air compressor and other air compressors are essential in a safe environment, and they may be equipped with a variety of safety valve testing tools.

Safety valve test benches are used to test and compress air at a pressure level. For preventing fluid from apart, they need to be compressed, or occasionally leaking.

Safety valve test benches are used to test air compressors, and other related products, such as air compressor, and other flushes. There are also safety valve test benches to test air compressors, and other related products such as air compressor, and other flushes. air testing benches for functional purposes such as air compressors, for example, and other flushes, and other products. Alibaba.com features a wide range of safety valve test benches for compressor air compressor, and many other products available, such as air compressor, and air flushes.

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The utility model is for satisfying the gas gathering and transportation device to be carried out the on-the-spot requirement that detects and debug with the safety valve performance parameter, and develops a kind of novel safety valve debugging apparatus.

The safety valve debugging apparatus, by air compressor machine, the source of the gas jar, gas-holder, the adjustment platform, switch board, the microcomputer testing management system, instrument and pipeline fittings constitute, the air compressor machine high-pressure air source is attached to the source of the gas jar by stop valve, source of the gas tank stores gases at high pressure and by control stop valve send into gas-holder, tested safety valve is installed on the adjustment platform that directly links to each other with gas-holder, switch board is concentrated installing pressure measuring instruments and pilot piping high sealing stop valve, the microcomputer testing management system is by safety valve adjustment platform, intelligent transducer, information module, computing machine, compositions such as LAN, intelligent transducer is installed on the safety valve adjustment stand of gas-holder outlet, it is characterized in that:

B, source of the gas jar, gas-holder adopt horizontal type structure respectively, and are provided with safety relief protective valve and tensimeter monitoring, in the gas-holder outlet microcomputer testing sensor contact are set;

C, adjustment platform are furnished with the above flange debugging frock of at least one cover, and the safety valve discharge flange is furnished with the noise reduction pipe fitting.

The utility model also is provided with pilot valve test gas-holder, adopts vertical installation, and gas-holder is provided with test pilot valve source of the gas control interface.

The utlity model has following advantage: 1. adopt the skid structure, innovatively the source of the gas jar, gas-holder, the adjustment platform, switch board, instrument and pipeline fittings are assembled into one on the skid base, make its compact conformation, convenient transportation, avoided on-the-spot complicated pipelines laying installation, be not subjected to any condition restriction during installation, can adapt to the field work condition of work especially, be beneficial to the online detection of oil-gas gathering and transportation system, solved at present big latus rectum, high pressure safety valve performance parameter test, the technical barrier that calibration equipment does not match is for the safety and reliability of gas gathering and transportation device provide necessary guarantee; 2. this device not only can satisfy the test of high pressure, big latus rectum safety valve performance parameter, also according to the needs of on-the-spot adjustment safety valve pilot valve, is furnished with pilot valve performance parameter test functional structure specially, be beneficial to and improve the on-the-spot test serviceability, carry out hermetic seal test detection needs for satisfying the gas gathering and transportation device with other valve type product, this device also is furnished with the gas source interface and the by-pass valve control of other valve type product of special detection, has had the characteristics and the effect of a tractor serves several purposes; 3. debugging of safety valve and management system combine with intranet, can realize the networking of safety valve testing management work, can implement management to the verification situation of safety valve in enormous quantities, comprise archives, verification and the maintenance status etc. of safety valve.Simultaneously, because database is left on the server, test data is fragile and lose, the test data personal error is little, true and reliable, from actual operating position analysis, this system can gather in real time to the force value in the checking procedure, measure set-pressure value, opening pressure value and blow pressure value exactly, the survey report of printout standard, and can also make things convenient for, promptly the every information and the data of safety valve be retrieved and inquired about, improve the automatization level of science, credibility and the management of safety valve testing process greatly.Can not only satisfy pilot operated safety valve pilot valve test and multiple universal valve performance test separately, but also have automatic recording functions such as the verification of measurement pressure, displacement, temperature and time, favourable technical application management and stroke analysis.

Use proof through the scene, this device output pressure is adjustable, the rate of rise is controlled, simple to operate, that operation detects data is accurate, can in time provide verification and report and carry out data management that performance is safe and reliable, the automaticity height.Can accurately test set-pressure, blowdown presssure and the blow pressure of PN≤16.0MPa, DN25～200mm specification safety valve, the accuracy class height, test specification is wide, and every technical performance index reaches the regulation of GB12242-1989, GB150-1998, " safe technology of pressure vessel supervision rules " standard.Satisfy the needs of national oil-gas gathering and transportation construction project, can be widely used in petroleum gas and adopt transporting operation district, collection defeated station, chemical industry metallurgical industry and safety valve testings at different levels station, market potential is big, has remarkable economic efficiency and social benefit.

Conventionally when we talk about oil lubricated screw air compressor maintenance, it is mostly about replacing consumables such as filters and lubricant on time. While these consumables have a defined usable life and have a direct effect on the efficiency and the life of the air compressor itself when not replaced on time, there are a few critical valves in the air compressor that require maintenance as well. Compressor valves directly affect the efficiency, safety, and the functionality of the screw air compressor. Let us understand some of the commonly available valves in a screw air compressor, why they need maintenance, and discuss some of the frequently asked questions about screw air compressor valves.

A screw air compressor is very similar to a human heart. While a human heart has tricuspid, pulmonary, mitral, and aortic valves, a screw air compressor has four critical valves namely air inlet, minimum pressure, blow down, and safety valves.

Air inlet valve is also commonly known as the ‘Intake valve’ which is typically assembled on the airend’s intake. The air inlet valve of a conventional fixed speed screw air compressor controls the air intake into the compressor. It remains closed when the compressor starts to lower the starting load on the main motor and when the desired working pressure is attained in the compressed air circuit and thus enabling the compressor’s motor to run without any load. In some compressors that are capable of providing a variable output by modulating the amount of air it sucks in, the inlet valve holds various opening positions to regulate the volume of air entering the compressor. The effective performance of the inlet valve directly affects the compressor’s capacity and its power consumption during load and no-load conditions.

The minimum pressure valve is typically assembled on the exit of the air-oil separation tank of a compressor. The minimum pressure valve acts as a check valve preventing back flow of compressed air into the airend, retains a minimum pressure in the compressor system for lubrication, offers a restriction to avoid a collapse of the air-oil separation filter, and ensures a suitable velocity of flow across the air-oil separator that ensures efficient air-oil separation. The effective performance of the minimum pressure valve directly affects the compressor’s lubrication, air-oil separation efficiency, and power consumption during load and no-load conditions.

The blow down valve is typically found on a dedicated exhaust line from the air-oil separation tank. The blow down valve evacuates the compressed air in the air-oil separation tank each time the compressor runs on a no-load and when the compressor shuts down to ensure there is no back pressure when the compressor starts to load next time. The blow down valve of a conventional screw compressor is typically actuated by a solenoid valve. The effective performance of the blow down valve affects the compressor’s power consumption during un-load, capacity of the compressor when running on load, and the life of the motor.

The safety valve is typically mounted directly on the air-oil separator tank. The only function of the safety valve is to blow off the compressed air in the air-oil separation tank when the pressure in the air-oil separation tank exceeds the set pressure of the safety valve and there by prevents the tank from cracking under high pressure. A malfunctioning safety valve affects the safe operation of the air compressor or results in leakage of compressed air continuously.

Though each compressor manufacturer has their own unique valve design, compressor valves in general contain moving parts such as springs, valve plates, and plungers that affect the opening and closing of the valves and rubber seals / seats that offer perfect sealing when the valves remain closed. These moving parts wear or lose their mechanical properties over a period of time and the sealing components typically ‘age’ over time and lose their effectiveness and will need to be replaced.

Compressor manufacturers typically design these components to operate efficiently for several thousand or millions of operation cycles. However, several factors such as variability in the demand pattern, sizing of the air compressor against a certain air demand, the environment in which the air compressor operates, promptness of preventive maintenance, etc. determine how long these valves efficiently operate.

Many times, it is difficult to identify a malfunctioning valve or a valve operating with worn-out parts as the compressor continues to generate air. The typical symptoms of a malfunctioning valve are loss in compressor"s capacity, increase in power consumption during load or/and unload, drop in discharge pressure, increase in oil carry-over and more load on motor. These symptoms are either difficult to notice or have other frequently common assignable causes such as air leak before suspecting the compressor valves.

Case studies show that operating a screw air compressor with a worn-out / malfunctioning valve could increase its overall power consumption by 10 - 15%. Power cost contributes to more than 75% of the compressor’s total life cycle cost over ten years and hence this is a significant impact. Unserviced valves also lower the life span of downstream accessories by half. In some cases, a malfunctioning safety valve may result in a catastrophe.

Air compressor manufacturers typically offer convenient valve maintenance kits for customers that contain the internal parts of the valve that wear or age out. Changing the valve kits is a much more sensible and economical option than changing the complete valve.

It is difficult or almost impossible to identify a malfunctioning valve unless it is opened for inspection. Hence it is absolutely mandatory that these valves are inspected for effectiveness every year and the internal moving parts replaced as a part of preventive maintenance once every year or two depending on the operating conditions of the air compressor. It is typical for compressor manufacturers to mandate a valve kit replacement once every two years as a proactive measure.

In particular, the safety valve must be inspected and certified every year per the local safety laws to ensure they are functional and efficient. Sometimes, replacing the safety valve entirely with a valid certificate for one year is more economical as the certification procedures could be equally expensive on an existing valve.

As stated before, it is challenging to identify a valve that is worn out unless it is opened and inspected, but there are a few indicators that a qualified compressor technician can use to deduct a malfunctioning valve.

Low duty cycle operation: A sophisticated screw air compressor in today’s day and age carries a convenient microprocessor-based human-machine interface that keeps track of operating hours of the compressor under load and un-load conditions and the number of load/unload counts the compressor is subjected to over a period of time. A higher un-load hours and load/unload count indicates that the air compressor is oversized against the actual air demand. This in turn indicates the air compressor ‘cycles’ frequently between load and un-load mode as opposed to running continuously on load. Every time a compressor ‘cycles’, the inlet valve, blow down valve, and minimum pressure valve is brought into play where their internals ‘actuate’. Frequent actuation of these valves results in a faster wear of the internals and hence results in shorter life.

High operating temperature: A compressor that runs on a high operating temperature affects the life of the valve’s sealing components, which causes them to ‘age’ fast.

Compressor not building pressure: If the air demand has not changed over time and the facility is relatively free of any air leakage, the air compressor is probably not delivering the rated output. There is a high probability that there is a malfunctioning valve.

Increase in compressor’s power consumption: An increase in the air compressor’s power consumption profile over a period of time where there has been no abnormal change in the air demand and usage pattern indicates an increase in either the load or un-load power. There is a high probability that this is because of a malfunctioning valve.

Based on the design philosophy adopted by the air compressor manufacturer, the oil lubricated screw air compressors could have a few more valves that are critical to functional performance that must be maintained as well. Some of the other valves frequently used in an air compressor are as follows:

Temperature control valve (also known as thermal valve) is used to regulate the flow of oil through the oil cooler based on the operating temperature.

Drain valves are used to drain lubricant at the time of lubricant change over or cleaning. Air compressors equipped with a moisture trap at the outlet of the after cooler also has a drain valve (automatic or timer based) to discharge water collected

The presence or absence of one of these valves and the type of actuation of these valves (electronic / mechanical) depends on air compressor’s design architecture. The Operation and Maintenance Manual (OMM) and the Piping and Instrumentation Diagram (P&ID) supplied by the air compressor manufacturer are excellent resources that explain the purpose, functioning, and maintenance requirements of these valves.

Many of the air compressor valves are highly specialized and exclusive. Their designs are usually complex and some even need special tools to service them. The internal components" build quality and material selection are extremely important and proprietary. Hence it is highly critical that only genuine valve kits issued by the air compressor manufacturer are used to maintain the valves. An inferior after-market replacement will most certainly compromise the performance of the entire compressor, void the original manufacturer"s warranty of the compressor, cause consequential damage to other parts of the compressor, and above all, be a safety hazard.

In conclusion, while it is important to change the screw air compressor"s filters and lubricants on time, it is equally important to perform preventive maintenance on these critical valves in a screw air compressor as recommended by the air compressor manufacturer. While the intake valve, minimum pressure valve, safety valve, and blowdown valve are critical to the performance and safety of the compressor, there could be other valves in the compressor that are critical and need maintenance. The air compressors sizing and the environment in which it operates are crucial factors that affect the life of the air compressor. Finally, it is critical to proactively service these valves using genuine kits issued by the compressor manufacturer to enable the air compressor performs efficiently and safely.

We offer high quality valves serving the compressed air, pressure washer, fluid power, fire protection, specialty gas & pneumatic industries. Purchase online today!

Safety should be the priority in any workplace environment, whether it’s a construction site, a factory or another setting. Business leaders want to make sure their employees are safe, maintain high morale among their workforce and reduce the possibility of damaged or broken machinery. By employing practical safety measures, your company can benefit from increased uptime and fewer repair or replacement expenses.

Having safety measures in place is especially important when working with air compressors and other high-powered machinery. Compressed air should be treated with the same amount of care as other energy sources, as misuse or a lack of the proper precautions can present risks. It’s essential that all operators have the proper training, have read all instruction manuals thoroughly and understand how to mitigate safety risks and potential damage. Manuals contain an abundance of valuable information and will tell you how to keep your compressors running for longer periods without damage or injury.

There are also plenty of other resources that discuss how to maintain safety when operating pneumatic tools and air compressors. This guide will take you through the basics of using an air compressor, what to check before use, what to monitor and how to keep operators and workspaces safe to minimize air compressor dangers.

Air compressors are useful for many jobs, but they can also become dangerous when not maintained properly or misused. Compressor machines, hoses, pneumatic tools and electric connections can all pose hazards in the workplace. Air compressor accidents could potentially cause harm to workers and machinery.

What are some of the most common hazards related to air compressors? They include electrical dangers, fumes, flying particles, high pressures and high noise levels.

Flying particles and debris: Highly pressurized air and pneumatic tools can cause flying debris. If it strikes an operator, the pieces can cause bodily injury, or they can become lodged in the machine, causing damage.

High pressures:If high-pressure air is injected into the body, dangerous conditions and injuries, such as air embolism, ruptured eardrums and ruptured organs, can result.

Operators and workers can mitigate these dangers by following proper safety measures and air compressor precautions, which we will discuss later in the guide.

Depending on where you’re working, the intake air can contain pollutants and contaminants that are harmful to your health. From carbon monoxide to dust and debris, the air in the compressor collects from the surrounding space. To keep yourself safe while using the compressor unit, you must work in an area with proper airflow or natural air access, as well as protective gear, such as a respirator or dust mask.

While the likelihood of a workplace fatality due to an air compressor failure is low, it can happen in some extreme circumstances. If a compressor tank explodes, it can endanger your workers’ lives, but typically, the highest amount of danger lies with the operator. Due to the high pressures and pneumatic tools attached, operators must abide by all safety rules and regulations, including having the proper protective gear.

Every operator needs to undergo proper training and learn the relevant safety standards before using an air compressor. If you upgrade your air compressors or make any repairs, it’s essential to update operators on any changes so they know how to use the machine correctly and know what to look out for. It’s also important to check air compressor safety regulations from the Occupational Safety and Health Administration (OSHA) and ensure you’re in compliance with any that apply to your uses or machines.

The way your equipment and workspace are set up can have a significant impact on safety. Some air compressor and workspace setup tips to keep in mind include:

Component pressure ratings: Make sure that all components, including hoses, pipes and fittings, are rated for the maximum pressure of the air compressor.

Relief valves: Relief valves automatically release air if the pressure in the tank gets too high. These valves are important air compressor tank safety features, so you should never attempt to adjust, bypass or remove them.

Drain valves: If your compressor has an electric drain valve, make sure it is at least a foot and a half above the ground. Electric drain valves must be kept away from moisture.

Workspace air circulation: Intake air contains pollutants and carbon monoxide that can be hazardous to your health. For these reasons and others, it’s essential to keep your workspace circulated with clean air at all times.

Workspace humidity: It’s important to keep the humidity in your workspace from getting too high. To decrease the moisture in the air, try increasing air circulation in the workspace, operating your compressor for longer periods, using a peripheral crankcase heater or adding a dryer to your compressed air system.

Before using a compressor, you need to check various components to make sure the machine will work properly. To keep track of any issues and ensure you’ve looked at all the necessary areas, create an air compressor safety checklist for your operators to complete before each job. Some of the elements you may want to look at include:

Oil level: It’s essential to check and see if the machine has an appropriate amount of oil. Using it without an adequate amount of oil can ruin it to the point of requiring costly repairs or replacement. If it needs more oil, add oil to the reservoir but be careful not to overfill it. Also, be sure to keep oil from spilling onto the exterior of the compressor.

Fuel level:To run an air compressor, you need to have a sufficient amount of fuel. It can be a pain to have to refill in the middle of a job, as it requires you to stop, allow the compressor time to cool off and then refill the tank. Don’t refuel your air compressor when it’s on or has been shut off for only a short time. You should only conduct refuels and oil changes when the machine is cold.

Air filter:Whether you use a given compressor every day or only every once in a while, check the air filter before use. If it appears dirty or clogged, you should remove and wash it — if you have the right kind of screen — or replace it with a new filter.

Air connection:Before turning on your air compressor, make sure that it is securely connected to the air source. If the connection is weak or loose, the compressor may not perform as expected, and parts could disconnect, potentially leading to injury.

Outlets: Ensure your air compressor is only used with outlets that have the proper grounding. If you plug an air compressor into an incorrectly grounded outlet, it could damage the machine’s electrical circuitry and even cause a fire.

There are also air compression safety tips and procedures for particular parts of the compressor. Three of these components include the pressure regulation devices, air receivers and distribution lines. Each of these is significant in maintaining a healthy machine and operating it safely.

Valves:Ensure that the safety valves on your air tank are set to at least 10% or 15 psi — whichever is greater — above the operating pressure of the compressor but never higher than the air receiver’s working pressure limit. If using an air compressor in freezing temperatures, check that the safety valves are positioned in a way that prevents water from collecting inside the unit. If a valve freezes, thaw it and empty the compressor tank before reactivating the unit. The machine should also have shielded blowoff valves so sudden blowoffs don’t result in equipment damage or injury.

Air intake: The air intake should receive air only from clean, outdoor sources. Place a filter or screen at the intake valve to keep the intake air clean.

Speed: Check the manual that came with your compressor for the maximum recommended speed and ensure that you never run your compressor at speeds exceeding this level.

Draining:If your air compressor doesn’t have an automatic drain, be sure to drain the air receiver regularly so liquid does not build up inside of it.

Gauges and valves: Ensure that your air receiver has a pressure gauge and a safety valve that meets the American Society of Mechanical Engineers (ASME) standards.

Air hoses:Don’t let air hoses become bent or kinked. Check distribution lines regularly for flaws, damage and imperfections and replace any defective air lines immediately.

Operators should also take certain precautions while operating air compressors and after completing a project using an air compressor. It’s essential to remain in control of compressor units at all times. Sound footing and standing on a level surface at a safe distance from the unit is crucial as is keeping your hands, clothing and hair away from the air nozzle and tools.

While you can use compressed air for cleaning certain objects at low pressures and with a nozzle, you should never use compressed air for cleaning clothing or human skin. Don’t use compressed air to pressurize a vessel, such as to empty oil from a gearbox, as these vessels aren’t designed to handle high pressures. Don’t dry bearings using compressed air, as doing so can cause excessive rotations speeds that can cause bearings to explode.

Also, be sure to wear the proper safety gear for the job. No matter what tool you’re using for a given project, it’s vital to wear protective gear for your ears and eyes at all times. According to the Center for Disease Control, an estimated 22 million workers face exposure to potentially harmful noise every year. The risks involved with failing to wear hearing guards might not always be apparent at first, but adverse effects due to exposure to noise are often experienced later, in some cases years down the line. Personal protective equipment (PPE) to consider includes goggles, face masks, rubber or leather gloves, steel-toed shoes and leather or PVC aprons. Cotton clothing is not an effective barrier to compressed air. Cover any part of the body that is at risk of coming into contact with compressed air or flying particles.

To prevent safety issues, it’s crucial to keep an eye out for any potential issues while you’re using an air compressor. Once you start the machine and begin your work, be sure to check the following items consistently:

Surroundings: In addition to managing your own safety, keep an eye out for other workers and ensure you’re keeping the surrounding area safe. Make sure that all your hoses, cables and wires are tucked away where no one can trip on them and that you keep your area clean.

Voltage:Pay close attention to your air compressor’s voltage. If repairs are needed, power down the machine, lock and tag out all power sources and release all pressure from the compressor. If your compressor is designed for indoor use, don’t use it outdoors, as rain or wet conditions can cause electrical problems.

Air source:Be sure to check the air source itself regularly to ensure optimal performance and efficiency. The air source should be clean and dry. You can use screens or filters to clean the incoming air.

Air inlet:At the inlet, the air that goes in should be clean and free of moisture and should not exceed the maximum recommended pressure. If the maximum pressure rating of a particular tool is surpassed, it could cause various dangers, such as cracks, undue velocity or faulty pressure or output torque.

Performing preventative maintenance is essential to keeping your compressor running smoothly and safely. It can increase the longevity of your machine and improve its capabilities. Running a clean, well-kept machine will also promote the wellbeing of your workers and operators and help manage air compressor risks.

Receive the proper training:Anyone performing maintenance on an air compressor should have received the appropriate training to ensure they conduct maintenance tasks correctly and safely.

Follow the manufacturer’s recommendations: To ensure safety in maintenance and operation, it’s important to follow the care and maintenace recommendations of your compressor’s manufacturer.

Disconnect power: Before performing maintenance work, shut off the machine and disconnect it from all power sources. Lock open the electrical switch for the compressor and tag it so no one starts it by mistake.

Clean the unit properly:Cleaning your air compressor regularly will improve its performance and extend its life. When it comes to cleaning carbon remnants from the various parts of an air compressor, it’s safe to use soapy water or a lye solution, but you should never use anything flammable, such as kerosene. Following every cleaning, completely purge the air system.

Lubricate properly:Don’t use oils with low flash points to lubricate compressor parts. These oils could combust due to the high temperatures produced by air compressors during operation. It’s essential, however, to keep parts lubricated with the proper oils and to avoid over-lubrication to prevent corrosion.

Take steps to prevent rust: One of the most dangerous possibilities when it comes to air compressors is a rusty tank. Rust increases the unit’s chances of combusting, putting anyone nearby in danger. To prevent rust due to the accumulation of liquid, use the underside valve to drain the tank daily. If a tank becomes rusted, don’t attempt to repair it. A rusted tank requires replacement.

Handle tools safely:Before you install, remove, fine-tune or perform any kind of maintenance on your pneumatic impact tools or accessory parts, shut off the source of air, bleed the air pressure and disengage the air hose.

Report faulty equipment immediately:If you notice that repair work is needed that goes beyond regular maintenance, tag out the machine so no one uses it. Then, report the issue as quickly as possible so the machine can be repaired.

Although proper maintenance can help extend the life of your air compressor, you may still occasionally need to troubleshoot issues. Follow these compressed air safety tips when troubleshooting your equipment:

Shut down your compressor:Turn off your compressor, disconnect it from power and bleed any remaining air pressure before doing any troubleshooting or repair work. Make sure that the shutoff valve is always within reach in case something goes wrong during operation.

Follow safety procedures for hose malfunctions:If a hose malfunctions or comes apart at the coupling, you can prevent whipping with two components. One is an air fuse of the proper size, which you should install in the hose upstream. The other is a whip-inhibiting device that is placed along the coupling of a hose. If an air hose does start whipping around uncontrollably or another similar air hose problem occurs, don’t try to stop and control it by grabbing the hose. To prevent injury, turn off the air source before touching the hose.

Use reliable parts: If a component becomes damaged or needs to be replaced for any reason, use only reliable, high-quality parts that are the correct size, material and type for your machine. Using the wrong parts or low-quality components can result in decreased compressor performance, damage to your equipment and safety hazards.

As one of the world’s leading sellers of compressed air products for nearly 100 years, Quincy Compressor offers an array of machines and parts for many industries. With our one-of-a-kind offers and round-the-clock support, we’ve supplied and serviced businesses in the automotive, manufacturing and construction sectors, among others.

People have various uses for compressed air, and at Quincy, we’ve got them all covered. With Quincy, there’s no application too demanding for our top-of-the-line products to handle with utmost ease and maximum efficiency. Everyone who shops with us receives support from our authorized partners, day or night, as well as industry-leading warranties on select compressor products.

If you’re in the market for compressed air devices or related equipment, explore our website, where you can download whitepapers for more information on our wide range of products. You can also contact your local authorized Quincy Compressor distributor for air compressor sales and service in your area.

Many processes involve the use of high pressure steam, water or air.  Piping systems carrying these fluids must be protected from over-pressures that could cause damage or injury.  A pressure relief valve is a device that opens to vent any pressure higher than the relief valve’s operating set point.  The water heater in your house, for example, has a pressure relief valve set to open at a pressure that is lower than the burst pressure of the heater tank.  That way if pressure inside the tank exceeds the relief valve’s set point pressure, the valve will open and vent the pressure before the tank is damaged – you get a wet floor but you don’t have to replace the heater tank.

Pressure relief valves come in all sizes and pressures and these are critical parts of a high pressure piping system carrying steam in an industrial plants, refineries, power plants, etc.  The ASME has established criteria for the size and set point pressures for relief valves operating in industrial systems.  Additionally, these valve are tested on a regular basis to insure that they open at the correct pressure and do not impede the flow of fluid as the pressure is vented.  The vales are tested at their operating pressures and temperatures, and the opening pressure and pressure drop through the valve as it vents must be measured.

There are testing laboratories that are used to test industrial pressure relief valves by simulating the operating conditions for water, air and steam.  One customer of Validyne has a test lab capable of generating up to 10,000 lbs. per hour of steam at 300 psig, air flows to 3500 SCFM at 500 psig and water flow rates of 500 gpm at 300 psig.  Pressure relief valves are tested depending on their operating conditions, and the valves are instrumented to verify correct operation at their set point pressure.

The Validyne product used to make relief valve measurements is the DP15 pressure transducers.  One transducer is used to measure the pressure upstream of the relief valve, a second DP15 measures the downstream pressure.  These transducers are 300 or 500 psi, depending on the test.    A third DP15 measures the pressure drop across the relief valve when it is flowing and this transducer is typically 100 In H2O full scale.  The DP15s are used because they can be mounted remotely from the control station.  A large steam relief valve, for example, is connected to piping with runs of 25 and 30 feet.  The DP15 can be mounted at the measurement point and the cable to the demodulator can be up to 50 feet with no compromise in calibration.

The pressure transducers are connected to Validyne CD23 demodulator with digital display.  The CD23 features large LED displays that are helpful for the operator to see while opening and closing large control valves during the test.  The display can be given directly in PSIG and the CD23 provides an analog output proportional to pressure that can be connected to a LabVIEW computer to record the pressures during the test. Alternatively the pressure sensors can also be connected to the USB2250 DAQ.

The Validyne CD23s and DP15s have given many years of service in this difficult environment and this reliability, plus the ability to interface to a data acquisition system make it a great solution for relief valve testing.

This section tells you about air brakes. If you want to drive a truck, bus, or pull a trailer with air brakes, you need to read this section. If you want to pull a trailer with air brakes, you also need to read Section 6: Combination Vehicles in this handbook.

Air brakes use compressed air to make the brakes work. Air brakes are a good and safe way of stopping large and heavy vehicles, but the brakes must be well maintained and used properly.

CDL Air Brake Requirements. For CDL purposes, a vehicle’s air brake system must meet the above definition and contain the following, which will be checked during the vehicle inspection test:

If the vehicle you use for your road test does not have these components, your vehicle will not be considered as having an air brake system and you will have a “No Air Brakes” (“L”) restriction on your CDL.

A full service brake application must deliver to all brake chambers not less than 90 percent of the air reservoir pressure remaining with the brakes applied (CVC §26502).

The air compressor pumps air into the air storage tanks (reservoirs). The air compressor is connected to the engine through gears or a v-belt. The compressor may be air cooled or cooled by the engine cooling system. It may have its own oil supply or be lubricated by engine oil. If the compressor has its own oil supply, check the oil level before driving.

The governor controls when the air compressor will pump air into the air storage tanks. When air tank pressure rises to the “cut-out” level (around 125 pounds per-square-inch or “psi”), the governor stops the compressor from pumping air. When the tank pressure falls to the “cut-in” pressure (around 100 psi), the governor allows the compressor to start pumping again.

Air storage tanks are used to hold compressed air. The number and size of air tanks varies among vehicles. The tanks will hold enough air to allow the brakes to be used several times, even if the compressor stops working.

Compressed air usually has some water and some compressor oil in it, which is bad for the air brake system. The water can freeze in cold weather and cause brake failure. The water and oil tend to collect in the bottom of the air tank. Be sure that you drain the air tanks completely. Each air tank is equipped with a drain valve in the bottom. There are 2 types:

Some air brake systems have an alcohol evaporator to put alcohol into the air system. This helps to reduce the risk of ice in air brake valves and other parts during cold weather. Ice inside the system can make the brakes stop working.

Check the alcohol container and fill up as necessary. (every day during cold weather). Daily air tank drainage is still needed to get rid of water and oil (unless the system has automatic drain valves).

A safety relief valve is installed in the first tank the air compressor pumps air to. The safety valve protects the tank and the rest of the system from too much pressure. The valve is usually set to open at 150 psi. If the safety valve releases air, something is wrong. Have the fault fixed by a mechanic.

You engage the brakes by pushing down the brake pedal (It is also called a foot valve or treadle valve). Pushing the pedal down harder applies more air pressure. Letting up on the brake pedal reduces the air pressure and releases the brakes. Releasing the brakes lets some compressed air go out of the system, so the air pressure in the tanks is reduced. It must be made up by the air compressor. Pressing and releasing the pedal unnecessarily can let air out faster than the compressor can replace it. If the pressure gets too low, the brakes will not work.

S-cam Brakes. When you push the brake pedal, air is let into each brake chamber. Air pressure pushes the rod out, moving the slack adjuster, thus twisting the brake camshaft. This turns the S-cam (it is shaped like the letter “S”). The S-cam forces the brake shoes away from one another and presses them against the inside of the brake drum. When you release the brake pedal, the S-cam rotates back and a spring pulls the brake shoes away from the drum, letting the wheels roll freely again. See Figure 5.2.

Disc Brakes.In air-operated disc brakes, air pressure acts on a brake chamber and slack adjuster, like S-cam brakes. But instead of the S-cam, a “power screw” is used. The pressure of the brake chamber on the slack adjuster turns the power screw. The power screw clamps the disc or rotor between the brake lining pads of a caliper, similar to a large c-clamp.

All vehicles with air brakes have a pressure gauge connected to the air tank. If the vehicle has a dual air brake system, there will be a gauge for each half of the system (or a single gauge with two needles). Dual systems will be discussed later. These gauges tell you how much pressure is in the air tanks.

This gauge shows how much air pressure you are applying to the brakes. (This gauge is not on all vehicles.) Increasing application pressure to hold the same speed means the brakes are fading. You should slow down and use a lower gear. Brakes that are of adjustment, air leaks, or mechanical problems can also cause the need for increased pressure.

A low air pressure warning signal is required on vehicles with air brakes. A warning signal you can see must come on when the air pressure in the tanks falls between 55 and 75 psi (or 1/2 the compressor governor cutout pressure on older vehicles). The warning is usually a red light. A buzzer may also come on.

Drivers behind you must be warned when you put your brakes on. The air brake system does this with an electric switch that works by air pressure. The switch turns on the brake lights when you put on the air brakes.

Some vehicles made before 1975 have a front brake limiting valve and a control in the cab. The control is usually marked “normal” and “slippery.” When you put the control in the “slippery” position, the limiting valve cuts the “normal” air pressure to the front brakes by half. Limiting valves were used to reduce the chance of the front wheels skidding on slippery surfaces. However, they actually reduce the stopping power of the vehicle. Front wheel braking is good under all conditions. Tests have shown front wheel skids from braking are not likely even on ice. Make sure the control is in the “normal” position to have normal stopping power.

Many vehicles have automatic front wheel limiting valves. They reduce the air to the front brakes except when the brakes are put on very hard (60 psi or more application pressure). The driver cannot control these valves.

All trucks, truck tractors, and buses must be equipped with emergency brakes and parking brakes. They must be held on by mechanical force (because air pressure can eventually leak away). Spring brakes are usually used to meet these needs. Powerful springs are held back by air pressure when driving. If the air pressure is removed, the springs put on the brakes. A parking brake control in the cab allows the driver to let the air out of the spring brakes. This lets the springs put the brakes on. A leak in the air brake system, which causes all the air to be lost, will also cause the springs to put on the brakes.

Tractor and straight truck spring brakes will come fully on when air pressure drops to a range of 20 to 45 psi (typically 20 to 30 psi). Do not wait for the brakes to come on automatically. When the low air pressure warning light, and buzzer first come on, bring the vehicle to a safe stop right away, while you can still control the brakes.

In newer vehicles with air brakes, you put on the parking brakes using a diamond-shaped, yellow, push-pull control knob. You pull the knob out to put the parking brakes (spring brakes) on, and push it in to release them. On older vehicles, the parking brakes may be controlled by a lever. Use the parking brakes whenever you park.

Caution.Never push the brake pedal down when the spring brakes are on. If you do, the brakes could be damaged by the combined forces of the springs and the air pressure. Many brake systems are designed so this will not happen. Not all systems are set up that way, and those that are may not always work. It is much better to develop the habit of not pushing the brake pedal down when the spring brakes are on.

Modulating Control Valves. In some vehicles a control handle on the dash board may be used to apply the spring brakes gradually. This is called a modulating valve. It is spring-loaded so you have a feel for the braking action. The more you move the control lever, the harder the spring brakes come on. They work this way so you can control the spring brakes if the service brakes fail. When parking a vehicle with a modulating control valve, move the lever as far as it will go and hold it in place with the locking device.

Dual Parking Control Valves. When main air pressure is lost, the spring brakes come on. Some vehicles, such as buses, have a separate air tank which can be used to release the spring brakes. This is so you can move the vehicle in an emergency. One of the valves is a push-pull type and is used to put on the spring brakes for parking. The other valve is spring loaded in the “out” position. When you push the control in, air from the separate air tank releases the spring brakes so you can move. When you release the button, the spring brakes come on again. There is only enough air in the separate tank to do this a few times. Therefore, plan carefully when moving. Otherwise, you may be stopped in a dangerous location when the separate air supply runs out. See Figure 5.3.

Truck tractors with air brakes built on or after March 1, 1997, and other air brakes vehicles (trucks, buses, trailers, and converter dollies) built on or after March 1, 1998, are required to be equipped with anti-lock brakes. Many commercial vehicles built before these dates have been voluntarily equipped with ABS. Check the certification label for the date of manufacture to determine if your vehicle is equipped with ABS. ABS is a computerized system that keeps your wheels from locking up during hard brake applications.

Most heavy-duty vehicles use dual air brake systems for safety. A dual air brake system has 2 separate air brake systems, which use a single set of brake controls. Each system has its own air tanks, hoses, lines, etc. One system typically operates the regular brakes on the rear axle or axles. The other system operates the regular brakes on the front axle (and possibly one rear axle). Both systems supply air to the trailer (if there is one). The first system is called the “primary” system. The other is called the “secondary” system. See Figure 5.4.

Before driving a vehicle with a dual air system, allow time for the air compressor to build up a minimum of 100 psi pressure in both the primary and secondary systems. Watch the primary and secondary air pressure gauges (or needles, if the system has 2 needles in one gauge). Pay attention to the low air pressure warning light and buzzer. The warning light and buzzer should shut off when air pressure in both systems rises to a value set by the manufacturer. This value must be greater than 55 psi.

The warning light and buzzer should come on before the air pressure drops below 55 psi in either system. If this happens while driving, you should stop right away and safely park the vehicle. If one air system is very low on pressure, either the front or the rear brakes will not be operating fully. This means it will take you longer to stop. Bring the vehicle to a safe stop, and have the air brakes system fixed.

This device allows air to flow in one direction only. All air tanks on air-brake vehicles must have a check valve located between the air compressor and the first reservoir (CVC §26507). The check valve keeps air from going out if the air compressor develops a leak.

You should use the basic 7-step inspection procedure described in Section 2 to inspect your vehicle. There is more to inspect on a vehicle with air brakes than one without them. These components are discussed below, in the order that they fit into the 7-step method.

Check the air compressor drive belt (if the compressor is belt-driven). If the air compressor is belt-driven, check the condition and tightness of the belt. It should be in good condition.

The manual adjustment of an automatic adjuster to bring a brake pushrod stroke within legal limits is generally masking a mechanical problem and is not fixing it. Further, routine adjustment of most automatic adjusters will likely result in premature wear of the adjuster itself. It is recommended that when brakes equipped with automatic adjusters are found to be out of adjustment, the driver takes the vehicle to a repair facility as soon as possible to have the problem corrected. The manual adjustment of automatic slack adjusters is dangerous because it may give the driver a false sense of security regarding the effectiveness of the braking system.

Brake drums (or discs) must not have cracks longer than 1/2 the width of the friction area. Linings (friction material) must not be loose or soaked with oil or grease and must not be worn dangerously thin (less than 1/4 inch). Mechanical parts must be in place, not broken, or missing. Check the air hoses connected to the brake chambers to make sure they are not cut or worn due to rubbing.

All air brake system tests in this section are considered important and each can be considered critical parts of the in-cab air brakes tests. The items marked with an asterisk (*) in this section are required for testing purposes during the vehicle inspection portion of the CDL skills test. They may be performed in any order as long as they are performed correctly and effectively. If these items are not demonstrated and the parameters for each test are not verbalized correctly, it is considered an automatic failure of the vehicle inspection portion of the skills test.

To perform this test, the driver must start with the engine running and with the air pressure built to governor cut-out (120–140 psi or another level specified by the manufacturer). The driver identifies when cut-out occurred, shuts off the engine, chocks the wheels if necessary, releases the parking brake (all vehicles) and tractor protection valve (combination vehicle), and fully applies the foot brake. The driver then holds the foot brake for 1 minute after stabilization of the air gauge. The driver checks the air gauge to see that the air pressure drops no more than 3 pounds in one minute (single vehicle) or 4 pounds in 1 minute (combination vehicle) and listens for air leaks. The driver must identify how much air the system lost and verbalize the maximum air loss rate allowed for the representative vehicle being tested.

For a Class A combination vehicle, if the power unit is equipped with air brakes and the trailer is equipped with electric/surge brakes, the pressure drop should be no more than 3 psi.

An air loss greater than those listed above, indicates a problem in the braking system and repairs are needed before operating the vehicle. If the air loss is too much, check for air leaks and fix any that are identified.

For testing purposes, you must be able to demonstrate this test and verbalize the allowable air loss for your vehicle. For testing purposes, identify if the air loss rate is too much.

To perform this test the vehicle must have enough air pressure so the low-pressure warning signal is off. The engine maybe on or off; however, the key must be in the “on” or “battery charge” position. Next, the driver begins fanning off the air pressure by rapidly applying and releasing the foot brake. Low-air warning devices (buzzer, light, and flag) must activate before air pressure drops below 55 psi or the level specified by the manufacturer. The driver must indicate the approximate pressure when the device gave warning and identify the parameter at which this must occur; no lower than 55 psi. See Figure 5.5.

For testing purposes, identify and verbalize the pressure at which the low air pressure warning signal activates and identify the parameter(s) at which this should occur. On large buses, it is common for low-pressure warning devices to signal at 80–85 psi. If testing in a large bus, identify the parameter(s) mentioned above (55–75 psi) and inform the examiner that your vehicle’s low-pressure warning devices are designed to activate at a higher pressure.

If the warning signal does not work, you could lose air pressure and not know it. This could cause sudden emergency braking in a single-circuit air system. In dual systems, the stopping distance will be increased. Only limited braking can be done before the spring brakes come on.

To perform this test, the parking brake (all vehicles) and tractor protection valve (combination vehicles) must be released; (engine running or not) as the driver fans off the air pressure. Normally between 20-45 psi (or the level specified by the manufacturer) on a tractor-trailer combination vehicle, the tractor protection valve and parking brake valve should close (pop out). On other combination vehicle types and single vehicle types, the parking brake valve should close (pop out). The driver must identify and verbalize the approximate pressure at which the brake(s) activated.

The parking brake valve will not pop out on buses that are equipped with an emergency park brake air reservoir (tank). If your bus is equipped with an emergency park brake air tank, you must perform the spring brake test for triple reservoir vehicles to check the automatic actuation of the spring brakes.

If the parking brake valve does not pop out when the air pressure has been reduced to approximately 20 psi, you must demonstrate that the spring brakes have activated. To do this, you must:

To perform this test, the engine must be running at normal operating idle, typically 600–900 rpms. Observe the air gauge to determine if the pressure builds at the proper rate. For dual air systems, the pressure should build from approximately 85 to 100 psi within 45 seconds. For single air systems (in pre-1975 vehicles), the pressure should build from approximately 50 to 90 psi within 3 minutes.

With a basically fully-charged air system (within the effective operating range for the compressor), turn off the engine, release all brakes, and let the system settle (air gauge needle stops moving). Time for 1 minute. The air pressure should not drop more than:

Wait for normal air pressure, release the parking brake, move the vehicle forward slowly (about 5 mph), and apply the brakes firmly using the brake pedal. Note any vehicle “pulling” to one side, unusual feel, or delayed stopping action.

Stopping distance was described in Section 2.6 under “Speed and Stopping Distance.” With air brakes there is an added delay, “brake lag”. This is the time required for the brakes to work after the brake pedal is pushed. With hydraulic brakes (used on cars and light/medium trucks), the brakes work instantly. However, with air brakes, it takes a little time (one half second or more) for the air to flow through the lines to the brakes. Thus, the total stopping distance for vehicles with air brake systems is made up of 4 different factors.

The air brake lag distance at 55 mph on dry pavement adds about 32 feet. Therefore, at 55 mph for an average driver under good traction and brake conditions, the total stopping distance is over 450 feet. See Figure 5.6.

If the low air pressure warning comes on, stop and safely park your vehicle as soon as possible. There might be an air leak in the system. Controlled braking is possible only while enough air remains in the air tanks. The spring brakes will come on when the air pressure drops into the range of 20 to 45 psi. A heavily loaded vehicle will take a long distance to stop because the spring brakes do not work on all axles. Lightly loaded vehicles or vehicles on slippery roads may skid out of control when the spring brakes come on. It is much safer to stop while there is enough air in the tanks to use the foot brakes.

If your vehicle does not have automatic air tank drains, drain your air tanks at the end of each working day to remove moisture and oil. Otherwise, the brakes could fail.