With the Springtime comes many outdoor activities in our house. Sometimes they are new, such as archery which just came about in our house in the last couple of weeks. The other item that it is time for is our family garden. While we have not started any plants from seed this year, and the opportunity to get to a garden center to purchase plants may not happen, we still want to be prepared. To do that, we prepared the same plot we have used in years past and laid down some landscaping fabric to try and kill off any unwanted weeds that have already started to sprout up through the dirt.
The next activity was to get the tiller out and perform a tune-up/maintenance on it. Sure enough, first, pull and the cord on the trusty engine lets go. The cord didn’t merely break, it looked like something from the Three Stooges as I almost fell backward from my pulling momentum and very nearly punched myself in the face. I proceeded to disassemble the pull-cord cage and found myself in unfamiliar territory.
Had this been another part of the engine, the carburetor, electrical kill switch, engine internals, or even the final drive to the tines, I would have been okay. Oddly enough, I have never had to replace one of these recoilers or the rope that comes on them. When you go to YouTube and search for a topic like this you will find a rather large amount of ways to perform a task like this.
Rather than doing that, I enlisted the help of a close friend who has worked for a lawn care/landscaping company for over a decade. He maintains every piece of equipment the company owns and uses. Needless to say, he has replaced quite a few pull ropes in his time. When I called, due to social distancing we couldn’t meet in person, he, of course, asked several questions about the tiller and in the end helped me to make sure I had the correct replacement rope.
We then set off to walk through the process and the entire thing took less than 15 minutes. When it was said and done the pull-start felt better than it had ever since I owned the piece of equipment and after sitting since last year still started on the second pull. Thank God for ethanol-free fuel that is still available at certain locations.
The point of this story is, what is received and viewed as a simple task for one can be a monumental task for someone else. While my mechanical aptitude was sufficient, I lacked the training and understanding as to why you would perform this process in a given order. My friend, the expert, did not lack that at this point in time. This process was something that was second nature to him.
This is very similar to point-of-use compressed air applications and the EXAIR team. Our team has experience from a multitude of industries and we all focus on utilizing compressed air efficiently and effectively. If we don’t know the process (which is rare) we are willing to learn and ask questions until we understand enough about your application that we can make an educated recommendation for an optimal EXAIR product. We are all here to help each other and to help our customers achieve their goals, so contact us when you need an expert.
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.
Now that Spring is officially here, my “honey-do” list has grown quite substantially as of late. Besides all the work we’ve done inside the house, moving our first son to his new room and putting the nursery back together for our second’s arrival, we now need to focus on the outside of the house (of course this is what my wife thinks is the #1 priority and hey, she is 9 months pregnant so I am going to agree!).
First on the list is pressure washing the siding and since we were expecting temperatures near 65° this past Saturday, I wasn’t going to mind being outside. One problem though, the pressure washer was buried in the garage behind plastic tubs of old baby clothes (thank goodness we held on to these), bicycles, bags of old toys/clothes for donation and every other thing we’ve “needed to hang on to”, which meant that I was going to need to clean the garage before I could clean the house. Adding another item to the already lengthy, spring-cleaning list.
Are you looking to do some clean up around your facility? If so, EXAIR has you covered with our Industrial Housekeeping Products. ALL of these units are compressed air operated and require no electricity to operate so there are no motors to wear out or moving parts, making them virtually maintenance free!
For liquid only clean up, we offer 3 different products:
Reversible Drum Vac – attaches to any standard 30, 55 or 110 gallon closed head drum. Capable of empty or filling a 55 gallon drum in less than 2 minutes.
Chip Trapper – incorporates the Reversible Drum Vac to filter solids from liquid and traps them in a reusable filter bag. The unit can they be turned into a pump to empty the filtered, clean liquid back to a tank or reservoir.
For dry materials, we offer 3 different products as well:
Chip Vac – Used for vacuuming wet or dry chips and deposits them into a steel drum.
Heavy Duty Dry Vac – Similar to the Chip Vac but made of hardened alloy construction for abrasion resistance and a higher vacuum rate.
Heavy Duty HEPA Vac – Used in dusty environments to filter contaminants to HEPA standards while providing the same high vacuum rate.
From time to time we have customers call in and say “We have one of your products and need another. But we installed it so long ago that we no longer have the paperwork to know which model we bought.” That’s a great thing to hear in a way. Our products have outlasted their filing system, and not only that, but now we have potential to solve another problem for the same customer.
When this happens, we can sift through our files to find out which model was purchased, or if the original purchase was made through a third party, we can determine the model number in other ways. We can use the dimensions, material of construction, description over the phone, or a photo emailed to an Application Engineer such as the one below.
But, the needs of the application don’t end there. We may be able to pinpoint the model number of the device currently in use, but we also need to confirm that this model will be suitable for the new application. For the end user that sent in the photo above, this meant the completion of a Cabinet Cooler Sizing Guide for new heat load calculation.
What we determine in many cases is that the new application has specific needs which dictate the use of a product with different attributes (in this case a different Btu/Hr rating on a Cabinet Cooler). Whether it is because of heat load, ambient temperature concerns, required material, or any other variable, we are sure to provide the most suitable solution.
As spring gains momentum and warmer months are to come, it may be time to consider an EXAIR Cabinet Cooler solution for an overheating electrical panel in your facility. Contact an EXAIR Application Engineer for help calculating heat load and choosing the right system.