Regulators are used to control operating pressure. They work based on utilizing a diaphragm or piston to balance the downstream pressure against an adjustable spring force. There are two basic types; relieving and non-relieving. Relieving allows downstream pressure to vent to atmosphere if it exceeds the 'set' pressure. Non-relieving are used where the air or other gas is not to be vented to atmosphere.
The two most important characteristics discussed and presented graphically in descriptive literature are Regulation and Flow.
Regulation Characteristics is the ability to hold a constant downstream pressure as upstream pressure is varied.
Flow Characteristics is the ability to hold a constant downstream pressure as the downstream flow varies.
In both cases the closer the results are to a constant, the better the performance is said to be.
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