Running out of pressure? Think about storage volume.
Consider this — remember when you had your 10-speed bike with those thin tires? You could ride quite fast, but when it came to filling up the tubes to the proper pressure, all it took was a small shot on the fill valve to change the pressure a lot.
Now with your mountain bike that had the fat, thick tires, it was different. With those wheels, you needed to drain off a lot of air to change the pressure even a little bit.
Similarly, if you don’t have enough storage receiver volume in your compressed air system, you can very easily run out of pressure when transient loads exceed the capacity of the compressor or piping system.
Consider something simple like a 10-cfm impact gun. If you only have about 10 gallons of local storage to use, this gun would pull the air pressure down by 20 psi even for a 10 second operation. But if there is 100 gallons of local storage, you can use the gun for more than a minute before the air in the storage tank drops by the same 20 psi — all without the compressor starting. Having larger storage gives you a bigger reserve of air to play with.
Having larger storage also slows down the air compressor cycles, allowing the pressure band to be narrowed, giving more constant pressure. And if you have screw compressors, the tanks will make for better system efficiency.
William Ketel says
An interesting bit of common sense, backed up by the universal gas equation: PV=nRT ! So as we make n, the mass of the gas, (air in this case) much larger, the effect of changes in V, (the gas volume), will have less effect on the pressure.
This is also effective, as the caption of the photo describes, in compensating for inadequate capacity of the air distribution system.