What Are Brass Safety Relief Valves?

In this blog post, you’ll read:Every flowing system that operates under heavy load or pressure needs a safety device. Otherwise, the whole system, including people and property, will be damaged due to overpressure.
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Every flowing system that operates under heavy load or pressure needs a safety device. Otherwise, the whole system, including people and property, will be damaged due to overpressure. But safety valves can help you with that. Read on until the end to learn everything about brass safety relief valves.

Safety relief valves play a pivotal role in various systems to ensure safe operations, preventing overpressure, which can lead to catastrophic failures. When made of brass, these valves combine the efficiency of safety mechanisms with brass’s durability and corrosion resistance. Let’s dive deep into understanding brass safety relief valves’ functionality and importance.

The brass safety relief valve is a spring-loaded pressure relief valve. It is used to release the excess pressure from a system when the pressure exceeds the limit. The purpose of this valve is to protect heat, liquid, or such systems from unexpected blasts or damages caused by overpressure.

150 psi set pressure safety valve
150 psi set pressure safety valve


A brass safety relief valve is a pressure-relieving device constructed primarily from brass, designed to automatically release a substance (usually a liquid or gas) from a boiler, pressure vessel, or other system when the pressure or temperature exceeds preset limits.

Construction and Operation:

1. Material – Brass:

  • Advantages: Brass, an alloy of copper and zinc, is known for its durability, resistance to corrosion, and excellent heat conductivity. It is often preferred for valves due to its long service life and its non-rusting properties.
  • Alloy Variations: Depending on the application, the brass used might have other alloying elements like lead for machinability or tin for additional corrosion resistance.

2. Main Components:

  • Spring: Hold the valve in a closed position until the internal pressure reaches a pre-set level.
  • Disc: Seals the valve and prevents the release of the medium (liquid/gas) until required.
  • Seat: The part of the valve against which the disc seals.
  • Bonnet: Provides an enclosure for the operational parts of the valve.

3. Working Principle: When the system’s pressure exceeds the set limit, the force exerted on the underside of the valve surpasses the spring’s force, causing the valve to open and release the substance. Once the pressure drops back to safe levels, the spring forces the disc back against the seat, sealing the system once more.

Applications of Brass Safety Relief Valves:

You can use brass safety relief valves in any system; it need a proper pressure level for smooth and safe operation. Also, if the components of your system are sensitive to excessive pressure, this valve can save your equipment from accidental damage. 

This valve is used in a wide range of applications for safety. For example, in heating systems like boilers, heat exchangers, reactors… and other applications such as air, liquid, oil, gas, pumps, power generators, multi-phase applications, and many more.

  • Domestic Water Systems: These valves are indispensable in household water systems, especially water heaters. They prevent the buildup of excessive pressure, which can result in bursting or malfunction.
  • Industrial Machinery: In industries that utilize pressurized systems or machinery, such as the petrochemical or food and beverage sectors, these valves safeguard against overpressure situations.
  • Gas Storage Systems: Brass safety relief valves are used in gas storage tanks to prevent excessive pressure buildup, which could be catastrophic given the flammable nature of many gases.
  • HVAC Systems: In heating, ventilation, and air conditioning systems, these valves prevent overpressure, especially in boilers and radiators.
  • Pumping Systems: Pumps that move fluids under pressure often incorporate safety relief valves to prevent damage from pressure surges or blockages downstream.
Safety Pressure Relief Valves

Benefits of Brass Safety Relief Valves:

  • Overpressure Protection: Their primary function is to provide a controlled outlet for pressures that could otherwise damage or burst a system.
  • Corrosion Resistance: Brass, being an alloy of copper and zinc, is naturally resistant to corrosion, making these valves durable in environments where moisture is prevalent.
  • Durability: Brass is renowned for its long lifespan, translating to a reduced need for valve replacements and system downtime.
  • Thermal Conductivity: Brass has high thermal conductivity, making it excellent for systems with rapid temperature changes, ensuring that the valve will respond quickly to pressure changes caused by temperature fluctuations.
  • Cost-Effective: Despite their crucial role and the benefits of brass, these valves are relatively affordable, especially when considering their longevity and the potential cost savings from preventing system failures.

Features of Brass Safety Relief Valves:

  • Set Pressure Indication: Most of these valves come with a set pressure rating, indicating the pressure at which they will activate.
  • Spring-Loaded Mechanism: Many brass safety relief valves use a spring mechanism to close the valve, which compresses when the internal pressure exceeds the valve’s set limit.
  • Sealed Construction: The valve’s design ensures that there are no leaks during normal operation, only releasing fluid or gas when the set pressure is surpassed.
  • Manual Release: Some models come with a manual release lever, allowing for manual system venting or testing of the valve.
  • Varied Connection Types: Depending on the application, these valves can have threaded, flanged, or other connection types to fit various systems seamlessly.

Understanding the applications, benefits, and features of brass safety relief valves helps users and technicians make informed decisions when selecting, installing, or maintaining such valves in different systems. Properly chosen and maintained valves ensure the safety and longevity of the equipment and the environment in which they operate in.

Different Types

There are three main types of brass safety relief valves out there. Those are conventionalbalanced bellows and pilot-operated safety relief valves. 

The conventional and balanced bellow types have a spring-loaded mechanism. The pilot-operated one combines a self-actuated auxiliary pressure relief valve with a primary relieving device.

Types of Brass Safety Relief Valves:

  1. Conventional Safety Relief Valves:
    • Function: These have a dome-shaped chamber over the valve disc to balance the forces. The chamber’s pressure can impact the valve’s set pressure.
    • Use: Ideal for systems where back pressure doesn’t vary much.
  2. Balanced Bellows Safety Relief Valves:
    • Function: Contains bellows that balance the effects of back pressure on the valve, ensuring consistent set pressure regardless of changes in back pressure.
    • Use: Suited for systems where back pressure might fluctuate.
  3. Pilot-Operated Safety Relief Valves:
    • Function: These use a secondary or “pilot” valve to control the operation of the main valve.
    • Use: Useful in systems requiring precise pressure control and where minor leakage can be tolerated.
  4. Vacuum Relief Valves:
    • Function: Allows air or an inert gas into a system to prevent the formation of a vacuum.
    • Use: Vital in systems where a vacuum can cause equipment collapse or implosion.
  5. Pressure/Vacuum Relief Valves:
    • Function: Combines the functionalities of both pressure relief and vacuum relief.
    • Use: Essential in tank protection where both overpressure and vacuum conditions can occur.

Sizes of Brass Safety Relief Valves:

Brass safety relief valves come in a wide range of sizes to suit different applications. The size is often determined by the inlet and outlet diameter of the valve and can vary significantly based on the system’s requirements.

  • Small Valves:
    • Sizes: Ranges from 1/8″ to 1/2″.
    • Use: Often found in domestic applications like water heaters or small compressed air systems.
  • Medium Valves:
    • Sizes: Typically between 3/4″ to 2″.
    • Use Common in larger household systems and smaller industrial applications.
  • Large Valves:
    • Sizes: 2.5″ and larger.
    • Use: Predominantly used in heavy industrial settings, including large-scale water systems, HVAC installations, and industrial machinery.

When selecting a brass safety relief valve, it’s essential to understand the type that best fits the application’s requirements. Equally crucial is selecting the correct size to ensure the valve functions effectively. Using a valve that’s too small can cause it to wear out quickly or not handle the pressure, while one that’s too big can be unnecessarily expensive and may not provide the precise relief needed.

Brass Safety Relief Valve Components

You can break a brass safety relief valve into three sections: the head, body, and inlet or leg

Firstly, on the head section, there is a cap covering the inner mechanism. Right underneath the cap, you will see a set pressure adjustable nut. This nut will allow you to adjust and set the pressure limit. In addition, there is a metal rod called steam. The adjustable nut is attached to the threaded end of the steam. And the rest of the steam goes down into the main body of the valve. 

Secondly, inside the body, you will notice a spring or metal spindle with two plates on either side. The steam runs through them and makes them work together with the spring. Also, another plate at the bottom of the steam is bigger than the spring plates. This is the seat plate that seals the valve seat. Finally, a hard metal bonnet covers the whole body part. 

The bonnet has threads inside at both ends. Upperside threads meet the steam threads below the adjustable nut. This is for making sure that the nut cannot move inside the valve body. The lower-sided bonnet thread connects the inlet port or nozzle with the valve. In addition, you will see another port at the side of the valve: the outlet port. All these components are set together to form a safety relief valve.

inside parts of safety valve
Inside parts of the safety valve

How a Brass Safety Relief Valve Works

The function of the brass safety relief valve is to control the pressure in a different pressure situation to protect the system. Let’s see how!

You can set the pressure limit of your choice on the valve using adjustable nuts. Tightening the nut clockwise will free some force from the spring… by letting the upper spring plate move up. This happens because the nut cannot move down as the bonnet stops it. So, it slides the steam up while tightening, and the spring pushes the upper plate. Rotating the nut backward will do the reverse.

After setting up the pressure limit, the spring holds the seat plate down at that pressure. So, the valve acts like a normally closed valve. But when the system runs, if the pressure goes beyond the set pressure… it begins to overcome the spring force and lift the seat plate to open the path. 

After that, the valve expels the media coming due to the extra pressure through its outlet. Then, when the pressure becomes routine, the spring again forces the seat plate down to seal the valve seat. Thus, a brass safety relief valve removes excess pressure from a system and prevents disastrous failures.

From Roto-Rooter

How To Buy

Brass Safety relief valves come with a variety of specifications. So, before deciding to buy one, match it with your requirements first.

Spring is the most important element of this valve. So, the spring should be made of stainless steel for efficient working.

Non-adjustable valves are available with a pre-set working pressure of 1.5, 2.5, 3, 6, 8, and 10 bars. Determine and select the proper one for your system.

Thread connections should be BSPP and NTP for a perfect installation. 

This valve has a working temperature range of 5-110 degrees Celsius. If your system doesn’t match with it, ask your supplier for a solution.

Sizes are available in 1/2″ and 3/4″. Choose the proper size and type according to your needs.

The Body finish is important to protect the valve surface. Sandblasted and nickel plating finishes work great.

Not all safety valves have approval for all types of applications. Ensure the valve you are choosing has approval for your application.

If your valve supplier cannot fulfill any of your demands or you don’t have any supplier, you can choose us. Plumberstar is the leading brass valve maker and supplier based in China. We can produce any type of safety relief valve for you. Check our brass safety relief valves for more information.

Top Relief Safety Valve
Top Relief Safety Valve

Important DOs for Brass Safety Relief Valves

Keep in mind these things to get better performance while using this valve:

· Install a safety relief valve maintaining the direction horizontal or vertical. Would you please not install it upside down? If so, it will not work correctly. 

· Do not cover the outlet with a plug or anything. Ensure to attach a pipe to the outlet and run it down to a safe place with the pipe end open.

· Check the valve regularly. Sometimes, some minerals and calcium are built up inside the outlet. If your valve has a lever, then lifting the lever will make the discharge clear. Moreover, if you see any drips or anything wrong, stay away from the valve and call the plumber immediately.

Hopefully, till now, you have understood the importance of brass safety relief valves. They are reliable and work as a lifesaver in a system. And if you have read all the above carefully, you can now use them in the right way. So, don’t take a risk and protect your property with brass safety relief valves.

Pressure Gauge Works For Safety Valve
Pressure Gauge Works For Safety Valve

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