How do Pressure Regulators work

How do Pressure Regulators work?

In some compressed air systems, the only pressure control is on the compressor itself - this almost certainly results in too much air consumption and wasted energy and money. Using a pressure regulator can solve this problem; we explain how they work and the different types.

Why have a pressure regulator?

Most tools and many components have an optimum pressure for working; this is invariably less than the operating pressure of the compressor. A device running at 7 bar will consume twice as much air as it would at 3 bar; so, the use of a pressure regulator, to reduce the working pressure, saves energy and money.

Depending on the system design, the inlet pressure of a compressed air system may fluctuate; a pressure regulator will maintain a constant outlet pressure for supply to devices.


How does a pressure regulator work?

The control knob is lifted and turned in a clockwise direction. This compresses a spring, which in turn places the load on the diaphragm assembly. The diaphragm pushes down on a valve pin connected to the valve seat and the seat drops; this allows downstream air flow from the inlet port (P1) out of the outlet port (P2). As air passes down P2 a breathe hole lets air into a chamber below the diaphragm; once pressure either side of the seat is equal, the seat closes with the aid of the sapring.

Downstream demand will cause a pressure drop in the chamber, opening the seat and allowing air to flow again until pressure is once more equalised and the seat closes. The process is continuous, maintaining P2 at a set value.


What types of pressure regulators are there?

Firstly, it is important to stress that a pressure regulator is NOT a flow controller; these are two different animals. In general, there are three types: General purpose, pilot operated and application specific, for example, used in precision instrumentation, reverse flow, brewery and other applications.

  • General purpose regulators are usually rated for 20 bar inlet pressure, with an outlet pressure up to 16 bar, dependent on the materials used in construction. A recommended range, over which the performance is repeatable, is always given.
  • Pilot operated regulators use air pressure in place of the compression spring discussed earlier. This allows control from a remote position, a force greater than that possible through a hand operated mechanical spring and better flow characteristics.
  • Precision regulators, as the name suggests, offer a finer adjustment of pressure over the recommended range. They would be used for the pilot supply to a pilot operated regulator. Some may require specific pre-filtering to, for example, ensure 5-micron oil-free air.

In all cases, pressure should be adjusted from a lower pressure gradually up to the set pressure.


What factors to consider when choosing a Pressure Regulator?

There are several factors to consider in choosing the correct Regulator for an application.

  • Operating pressure - what is the operating pressure at the input port and the required controlled pressure at the output? What is the precision required in control of the output pressure?
  • Flow requirement - as said above, a pressure regulator is not a flow controller, but clearly, there is a relationship between the two. All manufacturers will provide a graph showing flow as a function of pressure and it is important to make sure the required flow range is in a linear part of the line.
  • Operating fluid and environment - whilst we focus on compressed air as the medium, there are many applications with other gases; it is important that particularly the seals are resistant to any non-inert medium. The environment will impact choice; for example, in a hostile environment, it is likely that pilot operation will be required, so adjustments can be made remotely.
  • Operating temperature - materials chosen will be different for applications outside in the arctic circle, compared to a furnace!
  • Size and weight - some applications, for example medical, may have restrictions on these physical parameters.

More information

Browse our range of pressure regulators to find out more