An important part of operating and maintaining a compressed air system is taking accurate pressure measurements at various points in the compressed air distribution system, and establishing a baseline and monitoring with data logging. A Pressure Profile is a useful tool to understand and analyze the compressed air system and how it is functioning.
The profile is generated by taking pressure measurements at the various key locations in the system. The graph begins with the compressor and its range of operating pressures, and continues through the system down to the regulated points of use, such as Air Knives or Safety Air Guns. It is important to take the measurements simultaneously to get the most accurate data, and typically, the most valuable data is collected during peak usage periods.
By reviewing the Pressure Profile, the areas of greatest drop can be determined and the impact on any potential low pressure issues at the point of use. As the above example shows, to get a reliable 75 PSIG supply pressure for a device or tool, 105-115 PSIG must be generated, (30-40 PSIG above the required point of use pressure.) As a rule of thumb, for every 10 PSIG of compressed air generation increase the energy costs increase 5-7.5%
By developing a total understanding of the compressed air system, including the use of tools such as the Pressure Profile, steps to best maximize the performance while reducing costs can be performed.
If you have questions about getting the most from your compressed air system, or would like to talk about any EXAIR Intelligent Compressed Air® Product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.
Quick disconnect pneumatic fittings have been a staple in any manufacturing facility I have ever visited in my 10+ years as part of the manufacturing world. The fact is, they have been around for a lot longer than 10 years. The style we see most often is the 1/4″ Quick Disconnect Fitting, and we are typically troubleshooting a lack of air volume problem because they are not sized properly for the application. These can be found in any industrial supply companies catalog, your local hardware stores, and even auto parts stores. Quick Disconnects are even sold with certain EXAIR Industrial Housekeeping products, the key being they are properly sized.
Properly sizing the quick disconnect is a critical step in the process of deciding how to lay out your piping system as well as how to ensure products operate at optimal performance. As you can see in the picture above, the two quick disconnects on the left are both larger quick disconnects as well as larger NPT thread sizes. The two on the right are smaller and probably a bit more common to see. Also notice the thread sizes on each, these are also manufactured in many other NPT thread options. The through hole on the quick disconnects is decided by the size of the QD, not the thread size on the other end. The example I am illustrating is comparing the 3/8 NPT and 1/4 NPT quick disconnects: Even though you can have 3/8 NPT threads, your throat diameter of the QD is still restricted to .195″ I.D., the same as the 1/4 NPT. This can be a large restriction on a product with a 3/8 NPT thread size.
Also to be noted is that all QD’s of the same size are not made equally, tests have shown that you can lose as much as 20 psi through a quick disconnect and up to 40 psi when not properly matched with the female QD. This leads to the next step which is to ensure that you are not purchasing a QD on appearance. MAke sure to choose the QD designed to permit the amount of air you need to operate your point of use product without a volume or pressure loss.
These two points are reasons why quick disconnects can diminish your point of use compressed air product performance. If you have questions on which size to use with your EXAIR product or need help determining why your point of use product is not performing how you would like, contact us.
I would like to dive into the realm of filters and regulators. Majority of EXAIR products use compressed air to coat, conserve, cool, convey or clean. So, to keep the product running efficiently, we need to supply them with clean, dry, pressurized air. We offer a line of filter separators, oil removal filters, and regulators that can supply enough pressure and flow to keep the EXAIR products performing for a very long time. If we look at each individual item, we can see how they can play an important part in your compressed air system.
Regulators are used to control the amount of air pressure being supplied to your EXAIR products. This is important if you are trying to control the flow, force, and/or conveyance rate. One issue with regulators is “droop”. Droop is the amount of pressure drop when you flow through a regulator. If you set the pressure of a regulator with no flow, to let’s say 80 psig (5.5 barg). Once you start flowing, you will see the downstream pressure fall. This is dependent on the size of the regulator and the valve inside. This is very important because if you need 80 psig (5.5 barg) downstream of the regulator feeding an EXAIR product and the droop brings it to 30 psig (2 barg), you will not have enough flow for your EXAIR product, losing performance. EXAIR recommends a specific regulator for each of our products. We tested our products with the recommended regulators to make sure that you are able to get the best performance. If you do use another manufacturer’s regulator, make sure you are able to flow the correct amount of air at the pressure you need. Not all ¼” regulators flow the same.
Filter separators are used to remove liquid condensate and contamination from the compressed air stream. They have a 5 micron filter and work very well if you get a slug of water or oil into your compressed air system. They use mechanical separation to remove the large particles of dirt and water from the air stream. Most facilities have some type of compressed air dryer in their system. This will dry the compressed air. But, if a system failure occurs, then water, oil, and dirt are pushed into the compressed air lines and perhaps into your EXAIR products. Even if you have good quality air, it is important to keep your products protected. An ounce of prevention ….
The oil removal filters are used to keep the compressed air even cleaner yet. They work great at removing very small particles of dirt and oil. Without an oil removal filter, dirt particles and oil particles can collect in “dead” zones within the compressed air lines. Over time, a tacky glob forms. As it grows, it can break off and get into the air stream affecting pneumatic devices. The oil removal filter will be able to help eliminate the long term effects in your compressed air system. As a note, oil removal filters are not great for bulk separation. If you have a system with lots of water, you will need a filter separator in front of the oil removal filter to optimize the filtration. With the oil removal filters, the media is a barrier to collect the small particles of dirt and oil. If a slug of water or oil tries to go through, it will block a portion of the element off until it is forced through. This will increase the velocity and pressure drop of the element. With the high velocity, as the slug makes its way through the media, it can spray, re-entraining the liquid particles.
Now that we went through our pneumatic products, how do we use them together to get the best supply of compressed air? With both types of filters, we always want them to be upstream of the regulator. This is because the velocity is lower at higher pressures. Lower velocities mean smaller pressure drops which is good in filtration. If we can analyze the compressed air systems, I would like to categorize it into a good and premium quality. To supply a good quality of compressed air, you can have the compressed air run through the filter separator then a regulator. To produce the premium quality of compressed air, you can have your compressed air run through the filter separator, the oil removal filter, and then the regulator. With clean quality air, your EXAIR products will provide you with effective, long-lasting performance without maintenance downtime.
Quick Disconnects are a quick and easy solution to hook up devices to your compressed air system. These units can be found in quite a few factories and are more often than not being used incorrectly. I know that on the air compressor in my garage, the only way to hook anything up to it was to use 1/4″ quick disconnects. Chances are they are even a few of them within your facility, assuming you have compressed air available.
When you really look at a quick disconnect though you start to see why it shouldn’t be used to install every compressed air driven device there is. You can see in the pictures below that a 1/4″ quick disconnect that goes to a 3/8″ NPT adapter has a .192″ opening at the small end. A 3/8″ Schedule 40 iron pipe will actually carry a .493″ inner diameter. If you were to use this quick disconnect on something like a 2″ Heavy Duty Line Vac, you will starve it for air due to the limited ability of the small diameter to carry enough air volume. This, in turn, will limit the performance of the Line Vac. This is because the through hole on the quick disconnect cannot pass enough air to feed through to the Line Vac.
On the 1/4″ quick disconnect to a 3/8″ NPT this may not be as large as a problem as the next picture. Below you can see a 1/2″ quick disconnect that is going up to a 3/4″ NPT. a 3/4″NPT Schedule 40 iron pipe is actually a .824″ inner diameter. The quick disconnect at most has a .401″ inner diameter.
Even though you are providing the correct thread size for your connection (a 3/8 MNPT and a 3/4 FNPT respectively in our example) the quick disconnect’s small inside diameter could be too much of a restriction for the volume demanded by an end use product. Due to this restriction point you will see pressure drops in your system when using a device with a properly sized inlet for its demand of compressed air being fed with an improperly sized quick disconnect. This is one of the main reasons one of our first questions in troubleshooting an EXAIR products performance with a customer is whether or not they are using quick disconnects.
Last week I pointed out the important locations for measuring your compressed air system pressure throughout your compressed air system. One of the critical points to measure system pressure was before and after each filter. This leads into another question that I receive every once in a while, “How do I tell when the filter needs to be changed?” The answer to this is easy, when you see more than a 5 PSIG pressure drop across the filter. This means that the element within the filter has become clogged with sediment or debris and is restricting the volume available to your downstream products.
This can lead to decreased performance, downtime, and even the possibility of passing contaminants through the filter to downstream point of use components. In order to maintain an optimal performance when using EXAIR filter separators and oil removal filters, monitoring the compressed air pressure before and after the unit is ideal.
Replacement filter elements are readily available from stock, as well as complete rebuild kits for the filter units. Changing the filters out can be done fairly easily and we even offer a video of how to do it.
The life expectancy of a filter element on the compressed air is directly related to the quality of air and the frequency of use, meaning it can vary greatly. If you tie a new filter onto the end of a compressed air drop that has not been used in years, you may get a surprise by the filter clogging rather quickly. However, if you maintain your compressor and your piping system properly then the filters should last a long time. Generally we recommend checking your filters every 6 months.
If you have questions about where and why to filter your compressed air contact us.
In order to fully understand how efficient your compressed air system may be, you will need to generate a system pressure profile at some point. This is a list or diagram of what pressures you have in your compressed air system at specific locations, as well as the pressure required by all the demand devices on your compressed air system.
One of the reasons for the pressure profile is that you may have an application that is far away from the compressor but also highly dependent on a specific operating pressure. You may also find an application that, due to pressure losses within the system, causes an artificially high pressure demand.
The list below gives the critical points for measuring your compressed air system profile.
At the air compressor discharge. (If using multiple compressors, measure at each.)
If dryers of any type are being used after the compressor measure downstream from the dryer.
Downstream of each filter. (If a particulate filter and oil removal filter are being used it is best to measure downstream of each individual device. This is to tell when you have more than a 5 psig pressure drop or a clogged filter.)
At the point just before the main line from your compressor room branches off to distribution.
The furthest point of each header line you have installed.
On both sides of every filter/regulator units that are at high pressure point of use applications.
To give you an idea of why it is so important to measure these locations, take a look at the blogs we have posted on pressure drop. (Link Here) As you can tell by the list of blogs that comes up, pressure drop through piping can really cause a lot of wasted energy in your compressed air system. If you can get a good base line measurement by utilizing a pressure profile then you can start the process to optimizing your compressed air system.