Incorrect plumbing is an all too common problem we deal with on a regular basis here at EXAIR. Many times we receive calls from a customer saying that their Air Knife isn’t producing a high velocity or they are seeing an uneven airflow. In fact we have written many blogs touching on this subject, such as the one I posted a few weeks ago titled, Proper Air Supply & Installation Provides Best Performance or the one titled Typical Compressed Air Plumbing Mistakes by our International Application Engineer John Ball.
Using undersized supply lines can cause excessive pressure drops because they aren’t able to carry the volume of air necessary to properly supply the compressed air device. We commonly reference trying to supply water to a fire hose with a garden hose, it is the same principle. Using restrictive fittings, like quick disconnects, will also contribute to this effect as the ID of the fitting is much smaller than the NPT connection size. Example: Say you are seeing 80-100 PSIG upstream of an air knife at the pressure gauge, by the time the air passes through a quick disconnect or small ID line and fitting, the actual pressure being delivered to the unit will be much less, possibly as low as 20-30 PSIG depending on the installation. One way to measure the actual pressure being delivered to the air knife would be to install a pipe tee with a pressure gauge right at the inlet of the air knife.
All of our products are shipped with an installation guide referencing the proper recommended pipe sizes for various lengths of supply pipe. When dealing with our Air Knives, since we offer lengths up to 108″, you need to plumb air to multiple inlets for knives that are 24″ and larger. To simplify the installation process, we offer our Air Knife Plumbing Kits. The Plumbing Kits include properly sized nitrile/PVC compressed air hose and brass fittings for our aluminum units. In addition, we now offer 316ss pipe and fittings for our stainless steel and PVDF Super Air Knives for applications requiring superior corrosion resistance. Using the plumbing kits eliminates pressure loss and the need for searching for the proper fittings or possibly using incorrect pipe size.