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Demystifying Air Pressure Requirements for AODD Pumps There is generally much confusion and misinformation about the differences between Cubic Feet per Minute (CFM), Standard Cubic Feet per Minute (SCFM) and Pounds per Square Inch (PSI), Pounds per Square Inch – Gauge (PSIG) when it applies to powering an AODD pump. Even I get a bit tripped up but hopefully the information below will help us all better understand the terminology. In a future article, I will provide an overview of how to read and understand the different aspects of an AODD performance curve and what air force (PSI) and air flow (SCFM) requirements are called out depending on your duty point which is where Total Dynamic Head (TDH) and Fluid Flow requirements (GPM) intersect. As you can see, we love our pump acronyms so I will start keeping a list and share later. PSI/PSIG is technically defined as the pressure or intensity of air applied on one square inch on the surface of an object. For example, when you are pumping up a bicycle tire with a hand pump, it seems like it takes forever since the force of the air going into the tire is very low. There is a lot of surface area on the inside of that tire so it takes a lot of pumps of air to fill. Theoretically, PSI is used to tell how full you can make that tire using the hand pump with no time limit. CFM/SCFM is used to measure the volume/quantity of air flowing and technically called out as the amount of air within one cubic foot of volume. Back to the bicycle tire example above, if you were to use your handy-dandy garage air compressor which would provide much more flow of air, the time to fill the tire is much faster because the volume of the air is much higher than you can produce with a handheld tire pump. Clear as mud, huh? Rules of Thumb for CFM: [...]

I have been asked many times over the past 12+ years why anyone would want or need to use an Air-Operated Double Diaphragm (AODD) pump and I reply, “Why wouldn’t anyone want to use one?” I usually go into my list of multiple reasons why and they look at me as if I just recited them the Declaration of Independence rather than answer their specific question (I often tend to overexplain lots of simple features and benefits). There are lots of great reasons to use AODD pumps and I want to point out and discuss them and give real-world examples that tend to get lost in the higher-level discussions. Throughout this series of mini-articles, I would like to dig deeper into the many reasons for why you should choose an AODD pump and how they apply to your everyday pump selection process. Do You Have a Compressor? First and foremost, you must have a compressor as AODD pumps are by definition Air-Operated or Air-Powered or Air-Driven depending on where you are in the world. That being said, in general, you will need an industrial sized compressor to create enough energy to get the pumps to shift or reciprocate in order to get the fluid moving through the pump. A small, garage-sized pump generally cannot create enough energy (rated in SCFM – Standard Cubic Feet per Minute) to cycle the pump as most AODD pumps require 20-30 SCFM to “crack” the pump or make it start shifting. More on the compressor output requirements to come in future mini-articles. The investment in an industrial compressor can be sometimes overwhelming for some smaller companies who want to use a very few AODD pumps so they tend to stick with motor-driven pump technologies. In companies that already have a compressor on-site, it makes sense to include AODD pumps for transferring all kinds of chemicals and fluids. Applications like powering air tools or spraying equipment or even using a pneumatic impact wrench to change [...]