The Basics Of Pressure Regulators

Pressure regulators are found in many common home and industrial applications. For example, pressure regulators are used in gas grills to regulate propane pressure, in home furnaces to regulate natural gas, in medical/dental equipment regulate oxygen and anesthesia gases, in pneumatic automation systems to regulate compressed air, in engines to regulate fuel pressure, and in fuel cells to regulate hydrogen. Although the applications vary considerably, the pressure regulators provide the same function.  Pressure regulators reduce a supply pressure to a lower outlet pressure and they maintain this outlet pressure regardless of inlet pressure fluctuations.  This reduction in pressure is the key characteristic of pressure regulators; outlet pressure is always at a pressure below the inlet pressure.

When choosing a pressure regulator many factors are considered before selecting a product.   Important considerations include:  material choice, operating pressures (inlet and outlet), flow requirements, fluid used-(gas, liquid, hazardous or inert), temperature and size constraints.

Material:  A wide range of materials are available including but not limited to corrosion resistant stainless steels, brass, aluminum and plastic.  Stainless steel provides long life and is ideal for clean rooms and corrosive fluids.  When cost is a major contributing factor, brass, aluminum and plastic regulators may be the best option.  Aluminum is light weight while plastic is suitable for many medical applications involving bodily fluids.  Plastic fluid power products are often ideal when a throw away item is required.

Operating Pressures:  The inlet and outlet pressures are important factors to consider before choosing the best regulator. Important questions to answer are: What is the range of fluctuation in the inlet pressure?  What is the required outlet pressure? What is the allowable variation in outlet pressure?

Flow Requirements:  What is the maximum flow rate that the application requires? How much does the flow rate vary?  Porting requirements are also an important consideration.

Fluid used-(gas, liquid, hazardous or inert):  It is also important to consider the chemical properties of the fluid before determining the best materials for your application.  Each fluid will have it’s own unique characteristics so care must be taken to select the proper materials that will come in contact with the process fluid.  It is also important to determine if the fluid is flammable or hazardous in nature.  A non-relieving regulator is preferred for use with hazardous, explosive, or expensive gases since no gas is allowed to vent to atmosphere. A relieving regulator will vent excess downstream pressure to atmosphere.  The excess fluid should be vented safely and in accordance to all safety regulations.

Temperature: The materials selected for the pressure regulator not only need to be compatible with the fluid but also must be able to function properly at the expected operating temperature. The primary concern is whether or not the elastomer chosen will function properly throughout the expected temperature range. Additionally, the operating temperature may affect flow capacity and/or the spring rate in extreme applications.

Size & Weight- In many instances space is limited and weight becomes a factor.  Double check the port sizes, adjustment styles and mounting options available.