What is a PRV?

What is a RPV features

What is a PRV?

A PRV (Pressure Reducing Valve) is designed to open and relieve pressure at a set pressure point. Not to be confused with a pressure relief valve. PRV’s are designed to take higher pressure and reduce it down to a lower pressure.

Why do you need a PRV?

Controlling Pressure

The most common application for PRVs is for reducing the downstream pressure of Steam, Water, as well as other liquids and gases that are flowing through a pipe or system. When regulators are used for pressure reduction applications they are often referred to as Pressure Regulating Valves or Pressure Reducing Valves or simply PRV’s.

Controlling Temperature

Regulators can also be used to precisely control the flow of steam to accurately heat other liquids such as water flowing in a Heat Exchanger or contained in a Tank or Vat to extremely accurate temperatures. Regulators can also be used to accurately control the flow of water or glycol to cool down a process to a precise value. When regulators are used for any type of temperature control they are referred to as Temperature Regulators Valves or just Temperature Regulators.

Back Pressure Control

Regulating Valves can also be used to relieve over pressure conditions in Liquid systems or to maintain the “Back Pressure” in steam systems. When regulating valves are used in these types of applications they are referred to as Relief or back pressure Valves. Back pressures regulating valves used in steam applications must not to be confused with Safety Relief Valves.

Apex recommends Watson McDaniel brand PRVs

  1. Watson brand PRVs are robustly designed to handel the toughest steam services.
  2. Watson PRVs can utilize Spence brand Pilots or Watson can supply a pilot made for Spence valves. Interchangeability is a huge convenient factor for those who keep different brands in their facility.
  3. Watson PRVs are dimensionally equivalent to Spence. They even have the same face-to-face dimension. Changing out a Spence for a Watson is very easy.
  4. Watson PRVs are made of ductile iron. This makes them less expensive than cast steel.
  5. Watson products are USA MADE AND HAVE IN-STOCK INVENTORY! We can deliver to you quickly.
  6. Every PRV comes with a custom sizing sheet to show you exactly how you can expect your valve to perform.

Picking Your PRV

Watson McDaniel offers a wide range of different PRVs for you to choose from. Direct operated regulators are typically the most economical and can be a suitable choice particularly in the low to medium flow range. Pilot Operated Regulators will control downstream pressure more accuratly over a wider range of flows.

HD Series Pilot Operated Regulating Valves

HD Series – Pilot Operated

  • 1/2″ – 6″
  • Ductile Iron Body

The HD Series is used for pressure reduction or temperature control applications depending on pilot selection. They are commonly used for reducing steam pressure to a specific downstream set pressure. Other pilots are available for controlling temperature, back pressure, and other applications.



  • 1/2″ – 2″
  • Ductile Iron or Stainless Steel Body

The O-Series is the simplest and most economical choice for Pressure Reducing applications for a variety of fluids including: Steam, Water, Air, and other liquids and gases. These direct operated regulators have limited capacity.


Direct Operated Pressure Regulators

455 Series

  • 1/2″ – 4″
  • Bronze / Cast Iron Body

The 455 Series is for reducing pressure on Steam & Air applications. An external pressure sensing connection is required. The 455 Series is less susceptible to dirt and scale due to the lack of small pilot orifices.  These valves can be used in applications with low inlet pressure down to 5 psig due to a balanced seat and disc design.


Pilot Operated Pressure Regulating Valves

403 Series – Pilot Operated Reduction

  • 1/2″ – 4″
  • Ductile Iron Body

The 403 are pilot-operated, piston-actuated, pressure regulators. They are primarily used for reducing pressure in STEAM systems. These PRVs are available with an optional internal sensing line that simplifies installation. Piston Operated regulators are more compact in size.



  • 1/2″ – 4″
  • Bronze / Cast Iron Body

These are the primary choice for reducing pressure on Water, Air, and other liquid and gas applications. The soft-seated elastomeric Viton disc has an operating temperature up to 300ºF. It provides excellent shut-off characteristics. The balanced seat design eliminates internal forces. This extends the capability range of both pressure and capacity.


Discover All PRV’s Available From Apex Industrial Solutions


You will have learned the following:

  • What a PRV is and how it works
  • What brand the Apex team recommends and why
  • Different types of PRVs available for you and how they can fit into your processes

Contact Apex if you have any further questions regarding PRVs or any other parts in your process that can be improved!

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