The question comes up every so often. “I have 10 BARG plant pressure, but can only get 2 BARG pressure on the gauge at your Chip Vac.  What is the problem?”

We call the problem “pressure drop”. And pressure drop is attributed to many things. All of them have to do with the delivery of the compressed air supply up to the point of use or product.  In this case, the product was EXAIR’s 5 Gallon Chip Vac Model 6193-5. We found that actually having a pressure gauge installed right at the inlet of the Chip Vac vacuum generating part itself help greatly for the customer to realize the nature of their problem. The sources of such problems are usually to do with the diameter of the compressed air line feeding the “device” being too small. You will probably note in the photo that the customer has installed a 6 mm inside diameter line with a quick connect fitting. Upon further questioning of the customer, this supply line was 10 meters (33 ft) long. The Chip Vac requires 33 SCFM @ 80 PSIG (934 SCFM @ 5.5 BARG) to operate as advertised. Note this is the requirement at the inlet. Where you measure pressure in a compressed air system is of utmost importance. And for any compressed air consuming device, that value is going to be as used at the inlet, not at the wall or wherever the compressed air drop may be located.

Once the customer was able to increase to a 12 mm ID line and cut the length down to about 5 meters, the Chip Vac performed as intended. This was because it was no longer starving for compressed air through the smaller line.

We notice that many customers will try to get away with using too small a diameter of compressed air line. Perhaps it is what they had on hand or it was cheap to get. The problem is they end up shooting themselves in the foot when it comes to performance of the product connected out at the point of use.

By taking the time to practice proper plumbing technique, one can save themselves a lot of headache when setting up any pneumatic equipment. Of course, if you need advice on what the proper line size needs to be for any given installation, give us a call. We’ll be glad to assist you.

Neal Raker, Application Engineer
nealraker@exair.com