What storage is for
Demand in most plants is not steady. Tools start and stop, actuators fire together, a machine cycles. Without storage, every spike is met by the compressor, which either cycles load and unload or drops header pressure until it catches up. A receiver absorbs the spike, so the compressor sees an averaged demand and the tool sees a stable pressure.
What determines the size
| Factor | Effect on size |
|---|---|
| Peak flow above compressor capacity | Larger spike means more storage, or a compressor that can carry it |
| Duration of the spike | A short sharp demand needs less volume than a long one |
| Acceptable pressure drop | A tighter tolerance needs more volume for the same event |
| Load / unload band | Wider band allows a smaller receiver but a less stable header |
| Compressor control type | Variable speed needs less storage than load / unload cycling |
The relationship to remember
Storage volume, pressure swing and delivered air are linked: the air a receiver can give up equals its volume multiplied by the pressure drop you are willing to accept. If a spike needs a certain volume of air and the header may only fall by a certain amount, the receiver size follows. That is why raising the working pressure of a system without changing the receiver does not add usable storage - it only makes the machine work harder.
Standard sizes and ratings
Receiver tanks are commonly supplied from 300 to 2000 litres, rated at 8, 10, 13 or 16 bar, and the rating has to be at least the system's working pressure with margin. Undersizing the pressure rating to save cost is not a saving; it is a pressure vessel operating outside its design envelope.
Placement
Put the receiver where it does the most good: downstream of the dryer for general plant storage, and close to the largest intermittent consumer when one tool dominates demand. A receiver upstream of the dryer mainly protects the dryer from slugs of condensate, which is a different job.
Send us your working pressure, required flow and site conditions and we will propose a configuration. Contact OPPAIR.