Pressure regulator

A pressure regulator is a valve that automatically cuts off the flow of a liquid or gas at a certain pressure. Regulators are used to allow high-pressure fluid supply lines or tanks to be reduced to safe and/or usable pressures for various applications.

Operation

Pressure regulators don't simply stop flow when the source pressure is too high. Rather, they react to the pressure on their "output" side, and close when the pressure in the plumbing reaches the designated level. Should the pressure come down (for example, if someone were to open a faucet), the valve then opens and allows flow until the plumbing pressure goes back up (such as when the faucet is closed).

A typical pressure regulator uses the outside air as a reference to the baseline pressure. It regulates not on the pressure difference between the inlet and outlet, but rather the pressure difference between the outlet and the outside air.

Applications

Oxy-fuel welding and cutting

Oxy-fuel welding and cutting processes require gases at specific pressures, and regulators will generally be used to reduce the high pressures of storage cylinders to those usable for cutting and welding. Oxy-gas regulators usually have two stages: The first stage of the regulator releases the gas at a constant rate from the cylinder despite the pressure in the cylinder becoming less as the gas in the cylinder is used, as in the first stage of a scuba-diving regulator. The second stage of the regulator controls the pressure reduction from the intermediate pressure to low pressure. It is constant flow. The valve assembly has two pressure gauges, one indicating cylinder pressure, the other indicating hose pressure.

Propane/LP Gas

All propane and LP Gas applications require the use of a regulator. Because pressures in propane tanks can fluctuate significantly, regulators must be present to deliver a steady flow pressure to downstream appliances. These regulators compensate for tank pressures in excess of 200 psig and commonly deliver 11 inches water column for residential applications. Propane regulators differ in size, delivery pressure and adjustability but are uniform in their purpose to deliver a constant outlet pressure for downstream requirements. As is the case in all regulators, inlet pressure is higher than outlet pressure.

Recreational vehicles

For recreational vehicles with plumbing, a pressure regulator is a necessity. When camping, a source of water may have an enormous pressure level, particularly if it comes from a tank that is at a much higher elevation than the campground. Water pressure is dependent on how far the water must fall. Without a pressure regulator, the intense pressure encountered at some campgrounds in mountainous areas may be enough to burst the camper's water pipes or unseat the plumbing joints, causing flooding. Pressure regulators for this purpose are typically sold as small screw-on accessories that fit inline with the hoses used to connect an RV to the water supply, which are almost always screw-thread-compatible with the common garden hose.

Breathable air supply

Pressure regulators are used with air tanks used for breathing during SCUBA diving. The tank may contain pressures well in excess of 2000 PSI, which could cause fatal injury to a person breathing it. A regulator allows only a sustained flow of air at ambient pressure.

References

# http://www.irwd.com/WaterQuality/pressure.php