A shoe manufacturer had a special abrasion test that was required by his customer to test special rubber compounds. The set up was to run a small chain across the bottom of the rubber sole. The chain was looped to continuously rub against the sole of the shoe. As they began their wear testing, they noticed that the chain was getting hot from the friction. The heat would get high enough to change the composition of the rubber and cause a premature failure. To properly test for wear, they needed to cool the chain.
As they discussed their application with me, they required the chain to be at a specific temperature. I suggested the model 3925 Adjustable Spot Cooler System. This system comes with a dual point hose kit, a magnetic base, a filter separator, and two additional generators. The generators of the Adjustable Spot Cooler are a piece which controls the total volume of air through the cooler. They can be switched in and out to produce more or less cooling capacity of the Adjustable Spot Cooler. The main concern was to keep the chain temperature constant. With a temperature control knob and the additional generators, they could dial in the cooling capacity to keep the chain at the desired temperature. If the chain was too cold, the sole would not wear properly, and if the chain was too hot, it would change the composition of the rubber material.
They mounted the Adjustable Spot Cooler to the abrasion machine with the dual points blowing on each side of the chain. They quickly noticed that they could keep the chain cooler than the specified temperature. As a trial, they replaced the generator to the 30 SCFM (850 SLPM) flow rate. This increased the cooling capacity of the Spot Cooler. With the higher cooling capacity, they could increase the speed of the abrasion machine to shorten the failure cycle. This was a great benefit to have as they were testing different rubber compounds to determine the best product; a pronounced advantage in research and development.
If you find out that heat is causing problems in your application, you can contact an Application Engineer at EXAIR for help in finding the correct cooling product. In this instance, friction was the culprit and the Adjustable Spot Cooler was the solution.
I would like to discuss the importance of clean and dry filtered air. This all comes from some discussions I have had with customers over my time here at EXAIR, as well as from my time in the machine tool industry. It is notable to state that we simply ask for clean/dry air to run through our products, not “instrument” or “process” air which is typically held at a different pressure, temperature, or volume and can be more expensive to generate. All of EXAIR’s products use general plant air and can be cleaned up with simple point of use filters.
Clean and dry compressed air is essential for ensuring a long and easy life of almost any compressed air product. One product in particular that I have some data on is the EXAIR Line Vac. The pictures below show the inside wall of a Stainless Steel Line Vac. This unit was used in a harsh outdoor environment. The compressor was not maintained and did not have any form of filtration on the lines feeding the Line Vac unit. The first picture shows where all the dirt and particulate were impacting the internal generator wall as it entered the air chamber.
The two dark grey marks are actually the impact points on the unit. There is only one air inlet on the Line Vac, this means that the unit was taken apart during the two months and actually inspected then put back together and the generator was rotated slightly during this process. These spots are similar to what sandblasting does to metal, just to illustrate how much particulate was in the air stream. Since the air has not yet reached its full velocity within the Line Vac, it has left only those visible surface blemishes.
As the air begins to exit the array of small generator holes it begins to rapidly increase in velocity while it is trying to expand to atmospheric conditions. Because of this increased velocity, the wear the generator holes experience is greater and as seen below it is causing some extreme wear.
To give you an idea of what a new generator should look like is below. Here you can see uniform holes that go precisely through the generator.
To prevent a disaster like this from happening to your end-use compressed air products, all you need are some simple, low maintenance filters. EXAIR offers dirt / water filter separators that will filter your compressed down to 5 micron particulate size. The will catch the good majority of rust, water, and dirt within your compressed air system. Then you can also install an oil removal filter which will filter all oils and particulate out of your compressed air system down to 0.03 micron particulate level.
Each of these units are great point of use filtration to keep any of your processes from experiencing what this Line Vac experienced. If you have any questions about the quality of your compressed air or why you are seeing failures in product on your compressed air system, contact us.
I have run into another very good use of the Heavy Duty Line Vac and wanted to share this with you. A customer had contacted me from overseas. His interest was to apply Heavy Duty Line Vac to his abrasive media blast cabinets. The cabinets have a hopper filled with media that feeds a spray gun which accelerates the media toward a target work piece to remove anything from paint, to oxidation, oil and any other stubborn stains that might persist. That hopper is filled with Aluminum Oxide powder which is very abrasive and thus very good at the task of abrasive blasting.
The problem was in determining how best to replenish the hopper without having to stop and shovel the media back up to the feed hopper. In comes the EXAIR Heavy Duty Line Vac model 150125. The Heavy Duty Line Vac was fitted to a pipe which is connected to the tapered bottom of the media blasting cabinet. As the media falls down into the bottom, the Line Vac creates a powerful suction which conveys the Aluminum Oxide powder back up to the hopper for re-use.
The key to success for this application is the construction of the Heavy Duty Line Vac. These models are constructed from a hardened alloy material. This material makes for our most abrasion resistant model series available. Applications like this one where a stainless steel Line Vac might last 3 months, a Heavy Duty model can last 18 to 24 months or more of constant usage. Results will vary depending on application factors but there is no doubt that the Heavy Duty Line Vac is a highly reliable and effective tool to have for abrasive media conveying.