When any product / system is designed drawings are made to assist in the production of the designed product. For example if a mechanical part is being machined you may see symbols like these to verify the part is made correctly:
Same with an electrical panel, they use symbols like the ones below to note the type of equipment used in a location.
Then there’s the Piping & Instrumentation Diagram (P&ID)…it depicts an overall view of a system, showing the flow (usually fluid or electricity) through that system’s components, giving the viewer an understanding of the operation, and expected results from said operation.
Some examples of symbols you might find in a compressed air system are:
Air preparation & handling:
Instrumentation and control:
Occasionally, we’re asked if there are standard ANSI or ISO symbols for any of our engineered Intelligent Compressed Air Products…and there aren’t. Perhaps one day they might make the cut, but for now, their standard convention is to choose a shape and call it out by name. It might look something like this:
If you have questions about any of the quiet EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.
Since air compressors use a lot of electricity to make compressed air, it is important to use the compressed air as efficiently as possible. EXAIR has six simple steps to optimize your compressed air system. Following these steps will help you to cut your production costs and improve your bottom line. In this blog, I will cover the sixth step; controlling the air pressure at the point of use.
One of the most common pressure control devices is called the Regulator. It is designed to reduce the downstream pressure that is supplying your system. Regulators are commonly used in many types of applications. You see them attached to propane tanks, gas cylinders, and of course, compressed air lines. Properly sized, regulators can flow the required amount of gas at a regulated pressure for safety and cost savings.
EXAIR designs and manufactures compressed air products to be safe, effective, and efficient. By replacing your “old types” of blowing devices with EXAIR products, it will save you much compressed air, which in turn saves you money. But, why stop there? You can optimize your compressed air system even more by assessing the air pressure at the point-of-use. For optimization, using the least amount of air pressure to “do the job” can be very beneficial.
Why are regulators important for compressed air systems? Because it gives you the control to set the operating pressure. For many blow-off applications, people tend to overuse their compressed air. This can create excessive waste, stress on your air compressor, and steal from other pneumatic processes. By simply turning down the air pressure, less compressed air is used. As an example, a model 1100 Super Air Nozzle uses 14 SCFM of compressed air at 80 PSIG (5.5 bar). If you only need 50 PSIG (3.4 bar) to satisfy the blow-off requirement, then the air flow for the model 1100 drops to 9.5 SCFM. You are now able to add that 4.5 SCFM back into the compressed air system. And, if you have many blow-off devices, you can see how this can really add up.
In following the Six Steps to optimize your compressed air system, you can reduce your energy consumption, improve pneumatic efficiencies, and save yourself money. I explained one of the six steps in this blog by controlling the air pressure at the point of use. Just as a note, reducing the pressure from 100 PSIG (7 bar) to 80 PSIG (5.5 bar) will cut your energy usage by almost 20%. If you would like to review the details of any of the six steps, you can find them in our EXAIR blogs or contact an Application Engineer at EXAIR.
Imagine you’re enjoying a nice shower. A cascade of warm water is soothing your body – and spirit – then, someone starts the dishwasher. Or a load of laundry. Or flushes the toilet. Suddenly, the “soothe” turns to “scald” or “freeze,” depending on whether you’ve been robbed of hot, or cold water. So, what happened?
What happened is, all of those “loads” on your house’s water supply that can ruin your shower experience are controlled by simple on/off valves…they open to permit a certain amount of water FLOW to pass. When the dishwasher starts, or someone decides to wash a load of whites, the HOT water from your nice warm shower is diverted, leaving a stream of cold water. When a toilet flushes, or it’s a load of colors, the COLD water is diverted…and that’s not just unpleasant, but downright painful. Either way, (in my house anyway,) a teenager is getting read the riot act.
The same phenomenon can apply in a compressed air system, if simple flow control valves are used to throttle the appropriate supply of air to a pneumatic device. If someone, for example, hooks up an air gun to blow off their tools or parts, the valves on EVERYTHING else will need to be opened up some to keep those devices working the same. In the case of an air gun like this, it usually happens too quick to make the necessary adjustments (by hand) and you’re probably left with a machine tripped off-line, or a ruined part.
Pressure Regulators can prevent this by keeping (or regulating) their downstream pressure to a set value. If a load elsewhere in the system is activated, the Pressure Regulator opens up, automatically, to keep its output constant. When that load is secured, the Pressure Regulator closes back down accordingly. Either way, no single load affects the operation of any others.
That’s only half the value of the use of Pressure Regulators, though. The other half is, well…the value. Just looking at a typical function of many EXAIR Intelligent Compressed Air Products – blow off – they’ll all pretty much accomplish the task if you run them, unrestricted, straight off your header. That’ll give you a good, strong blast of air flow…and it may be more than what’s required, and a waste of good air. Pressure Regulators will prevent this by allowing you to “dial in” the supply pressure to whatever it takes to get the job done, and no more.
Compressed air isn’t free. Heck, it isn’t even cheap. Don’t use any more than you have to, and get the most out of what you do use. Pressure Regulators are one important step in doing this. If you’d like to talk about optimizing your use of your compressed air system, give me a call.
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To understand the value of a having a Pressure Regulator at every point of use we should start with identifying the two types of Pressure Regulators, Direct Acting & Pilot Operated. Direct Acting are the least expensive and most common (as shown above), however they may provide less control over the outlet pressure, especially if they are not sized properly. However when sized properly they do an outstanding job. Pilot Operated Regulators incorporate a smaller auxiliary regulator to supply the required system pressure to a large diaphragm located on the main valve that in turn regulates the pressure. The Pilot Operated Regulators are more accurate and more expensive making them less attractive to purchase. The focus of this Blog will be on the Direct Acting Pressure Regulator.
The Direct Acting Pressure Regulator is designed to maintain a constant and steady air pressure downstream to ensure whatever device is attached to it is operated at the minimum pressure required to achieve efficient operation. If the end use is operated without a regulator or at a higher pressure than required, it result’s in increased air demand and energy use. To clarify this point, if you operate your compressed air system at 102 PSI it will cost you 1% more in electric costs than if the system was set to run at 100 PSI! Also noteworthy is that unregulated air demands consume about 1% more flow for every PSI of additional pressure. Higher pressure levels can also increase equipment wear which results in higher maintenance costs and shorter equipment life.
Sizing of the Air Regulator is crucial, if it is too small to deliver the air volume required by the point of use it can cause a pressure drop in that line which is called “droop”. Droop is defined as “the drop in pressure at the outlet of a pressure regulator, when a demand for compressed air occurs”. One commonly used practice is to slightly oversize the pressure regulator to minimize droop. Fortunately we at EXAIR specify the correct sized Air Regulator required to operate our devices so you will not experience the dreaded “droop”!
Another advantage to having a Pressure Regulator at every point of use is the flexibilty of making pressure adjustments to quickly change to varying production requirements. Not every application will require a strong blast sometimes a gentle breeze will accomplish the task. As an example one user of the EXAIR Super Air Knife employs it as an air curtain to prevent product contamination (strong blast) and another to dry different size parts (gentle breeze) coming down their conveyor.
EXAIR products are highly engineered and are so efficient that they can be operated at lower pressures and still provide exceptional performance! This save’s you money considering compressed air on the average cost’s .25 cents per 1000 SCFM.
A few weeks ago, we posted a blog discussing how artificial demand and leaks can lead to poor performance and expensive waste. Today, I’d like to review how following a few simple steps can help optimize your current compressed air system and reduce compressed air usage.
The first step you want to consider is measuring the air usage in the system. To do this, you want to start at the compressor and check individual leads to each drop point to a blowoff device, record your findings to track the demand. By measuring your compressed air usage, you can locate the source of high usage areas and monitor the usage on each leg of the system. If the demand exceeds the supply, there is potential for problems to arise, such as lowered pressure and force from compressed air operated devices leading to irregular performance.
EXAIR’s Digital Flowmeters are designed to measure flow continuously and accurately to give you real-time flow measurements of your compressed air system to help identify problems areas.
Step 2 is to locate the source of waste. Again, compressed air leaks can result in a waste of up to 30% of a facility’s compressor output. A compressed air leak detection and repair program can save a facility this wasted air. Implementing such a program can be used as a way for a facility to “find” additional air compressor capacity for new projects. Whenever a leak occurs, it will generate an ultrasonic noise.
Our Ultrasonic Leak Detector is designed to locate the source of ultrasonic sound emissions up to 20’ away. These ultrasonic sound emissions are converted to a range that can be heard by humans. The sound is 32 times lower in frequency than the sound being received, making the inaudible leaks, audible through the included headphones and the LED display gives a visual representation of the leak.
The 3rd step involves finding the source of noisy and wasteful blowoffs, like open pipes or homemade blowoffs, and replacing them with an energy efficient, engineered solution. By replacing these devices, you are not only reducing the amount of waste but also improving operator safety by complying with OSHA safety requirements.
EXAIR’s Digital Sound Level Meter is an easy to use instrument that measures and monitors the sound level pressure in a wide variety of industrial environments. The source of loud noises can be quickly identified so that corrective measures can be taken to keep sound levels at or below OSHA maximum allowable exposure limits.
The easiest way to reduce compressed air usage and save on operating expense is to turn off the compressed air to a device when it isn’t needed, step 4 in the process. Not only will this save money, in many cases, it can also simplify a process for the operator.
A simple manual ball valve and a responsible operator can provide savings at every opportunity to shut down the air flow.
For automated solutions, a solenoid valve can be operated from a machine’s control. For example, if the machine is off, or a conveyor has stopped – close the solenoid valve and save the air.
A foot pedal valve offers a hands free solution to activate an air operated device only when needed, such as being implemented in an operator’s work station.
For even more control, you can use a device like our EFC or Electronic Flow Control. This helps minimize compressed air usage by incorporating a programmable timing controlled (0.10 seconds to 120 hours) photoelectric sensor to turn off the compressed air supply when there are no parts present. It is suited for NEMA 4 environments and can be easily wired for 100-240VAC.
Step 5, intermediate storage. Some applications require an intermittent demand for a high volume of compressed air. By installing a receiver tank near the point of high demand, there is an additional supply of compressed air available for a short duration. This will help eliminate fluctuations in pressure and volume.
EXAIR offers a 60 gallon, ASME approved vertical steel tank with mounting feet for easy installation near high demand processes.
Many pneumatic product manufacturers have a certain set of specifications regarding performance at stated input pressures. In many applications, or in the case of using a homemade blowoff device like open pipe, these wouldn’t necessarily require the full rated performance of the device or full line pressure. Controlling the air pressure at the point-of-use device will help to minimize air consumption and waste, step 6.
By simply installing a pressure regulator on the supply side, you can start off at a low pressure setting and increase the pressure until the desired result is achieved. Not only will this help to conserve energy by only using the amount of air required for the application, it also allows you to fine tune the performance of the point-of-use device to match the application requirements.
If you have any questions, please contact an application engineer at 800-903-9247.
Compressed air regulators are a pressure reducing valve that are used to maintain a proper downstream pressure for pneumatic systems. There are a variety of styles but the concept is very similar; “maintain a downstream pressure regardless of the variations in flow”. Regulators are very important in protecting downstream pneumatic systems as well as a useful tool in saving compressed air in blow-off applications.
The basic design of a regulator includes a diaphragm, a stem, a poppet valve, an orifice, compression springs and an adjusting screw. I will break down the function of each item as follows:
Diaphragm – it separates the internal air pressure from the ambient pressure. They are typically made of a rubber material so that it can stretch and deflect. They come in two different styles, relieving and non-relieving. Relieving style has a small hole in the diaphragm to allow the downstream pressure to escape to atmosphere when you need to decrease the output pressure. The non-relieving style does not allow this, and they are mainly used for gases that are expensive or dangerous.
Stem – It connects the poppet valve to the diaphragm. This is the “linkage” to move the poppet valve to allow compressed air to pass. As the diaphragm flexes up and down, the stem will close and open the poppet valve.
Poppet valve – it is used to block the orifice inside the regulator. It has a sealing surface to stop the flowing of compressed air during zero-flow conditions. The poppet valve is assisted by a spring to help “squeeze” the seal against the orifice face.
Orifice – it is an opening that determines the maximum amount of air flow that can be supplied by the regulator. The bigger the orifice, the more air that can pass and be supplied to downstream equipment.
Compression springs – they create the forces to balance between zero pressure to maximum downstream pressure. One spring is below the poppet valve to keep it closed and sealed. The other spring sits on top of the diaphragm and is called the adjusting spring. This spring is much larger than the poppet valve spring, and it is the main component to determine the downstream pressure ranges. The higher the spring force, the higher the downstream pressure.
Adjusting screw – it is the mechanism that “squeezes” the adjusting spring. To increase downstream pressure, the adjusting screw decreases the overall length of the adjusting spring. The compression force increases, allowing for the poppet valve to stay open for a higher pressure. It works in the opposite direction to decrease the downstream pressure.
With the above items working together, the regulator is designed to keep the downstream pressure at a constant rate. This constant rate is maintained during zero flow to max flow demands. But, it does have some inefficiencies. One of those issues is called “droop”. Droop is the amount of loss in downstream pressure when air starts flowing through a regulator. At steady state (the downstream system is not requiring any air flow), the regulator will produce the adjusted pressure (If you have a gage on the regulator, it will show you the downstream pressure). Once the regulator starts flowing, the downstream pressure will fall. The amount that it falls is dependent on the size of the orifice inside the regulator and the stem diameter. Charts are created to show the amount of droop at different set pressures and flow ranges (reference chart below). This is very important in sizing the correct regulator. If the regulator is too small, it will affect the performance of the pneumatic system.
The basic ideology on how a regulator works can be explained by the forces created by the springs and the downstream air pressures. The downstream air pressure is acting against the surface area of the diaphragm creating a force. (Force is pressure times area). The adjusting spring force is working against the diaphragm and the spring force under the poppet valve. A simple balanced force equation can be written as:
Fa ≡ Fp + (P2 * SA)
Fa – Adjusting Spring Force
Fp – Poppet Valve Spring Force
P2 – Downstream pressure
SA – Surface Area of diaphragm
If we look at the forces as a vector, the left side of the Equation 1 will indicate a positive force vector. This indicates that the poppet valve is open and compressed air is allowed to pass through the regulator. The right side of Equation 1 will show a negative vector. With a negative force vector, the poppet valve is closed, and the compressed air is unable to pass through the regulator (zero flow).
Let’s start at an initial condition where the force of the adjusting spring is at zero (the adjusting screw is not compressing the spring), the downstream pressure will be zero. Then the equation above will show a value of only Fp. This is a negative force vector and the poppet valve is closed. To increase the downstream pressure, the adjusting screw is turned to compress the adjusting spring. The additional spring force pushes down on the diaphragm. The diaphragm will deflect to push the stem and open the poppet valve. This will allow the compressed air to flow through the regulator. The equation will show a positive force vector: Fa > Fp + (P2 * SA). As the pressure downstream builds, the force under the diaphragm will build, counteracting the force of the adjusting spring. The diaphragm will start to close the poppet valve. When a pneumatic system calls for compressed air, the downstream pressure will begin to drop. The adjusting spring force will become dominant, and it will push the diaphragm again into a positive force vector. The poppet valve will open, allowing the air to flow to the pneumatic device. If we want to decrease the downstream air pressure, the adjusting screw is turned to reduce the adjusting spring force. This now becomes a negative force vector; Fa < Fp + (P2 * SA). The diaphragm will deflect in the opposite direction. This is important for relieving style diaphragms. This deflection will open a small hole in the diaphragm to allow the downstream air pressure to escape until it reaches an equal force vector, Fa = Fp + (P2 * SA). As the pneumatic system operates, the components of the regulator work together to open and close the poppet valve to supply pressurized air downstream.
Compressed air is expensive to make; and for a system that is unregulated, the inefficiencies are much greater, wasting money in your company. For blow-off applications, you can over-use the amount of compressed air required to “do the job”. EXAIR offers a line of regulators to control the amount of compressed air to our products. EXAIR is a leader in manufacturing very efficient products for compressed air use, but in conjunction with a regulator, you will be able to save even more money. Also, to make it easy for you to purchase, EXAIR offer kits with our products which will include a regulator. The regulators are already properly sized to provide the correct amount of compressed air with very little droop. If you need help in finding the correct kit for your blow-off application, an Application Engineer at EXAIR will be able to help you.