What is Pressure Relief Valve?

In this blog post, you’ll read:Temperature and pressure relief valves (TPRVs) are safety valves. It is used in many systems to stop excessive pressure and temperature buildup. Moreover, high pressure can cause equipment failure,
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Pressure Relief Valve Benefits

Pressure relief valves (TPRVs) are safety valves. It is used in many systems to stop excessive pressure and temperature buildup. Moreover, high pressure can cause equipment failure, explosions, or fires. TPRVs are installed on water heaters, boilers, and other pressurized vessels. They track the temperature and pressure levels. It releases extra pressure and temperature when it exceeds the safe operating limits.

The valve works by opening the valve. It allows water to escape when the pressure or temperature reaches a critical point. Thereby, it is preventing a catastrophic failure of the equipment. The TPRV is designed to discharge the excess pressure and temperature in a controlled way. It minimizes the risk of damage to the equipment or harm to people.

water heater tank
water heater tank

Why do we need a pressure relief valve?

TPRVs are critical safety valves that help protect pressurized systems from failures. Here are some reasons why TPRVs are necessary:

Prevents high pressure:

TPRVs are designed to release excess pressure when it exceeds the safe level of the equipment. This prevents the equipment from becoming over-pressurized. The high pressure leads to damage to the system.

Prevents high temperature:

TPRVs also protect against high-temperature conditions. It occurs when the equipment overheats or when there is a malfunction. High-temperature conditions can cause equipment failure. This prevents by releasing the excess heat through the TPRV.

Regulatory compliance:

Many regulatory bodies need the installation of TPRVs on certain types of equipment. You can install it on the main line of water heaters and boilers.

Protects property:

TPRVs protect people and property from harm by preventing dangerous equipment failures. By releasing extra pressure and temperature in a controlled way, it reduces the risk of damage to the system.


A TPRV contains several parts that work together. These parts prevent dangerous high pressure and temperature in the system. Here are the main components of a TPRV:

  1. Body: The body of the TPRV is the main housing that contains the valve’s internal components.
  2. Inlet port: The inlet port is the opening in the body where pressurized fluid enters the TPRV.
  3. Seat: The seat is part of the valve that seals the inlet port when the valve closes.
  4. Spring: The spring is a crucial component that controls the pressure at which the TPRV opens. It is made of a strong material such as stainless steel.
  5. Valve disc: The valve disc is a moveable component held in place against the seat by the force of the spring.
  6. Pressure-sensing element: The pressure-sensing part is a small device in the TPRV. It responds to changes in pressure by flexing or deforming. It is often a spring-loaded diaphragm or piston.
  7. Discharge pipe: The discharge pipe is a tube or pipe. It carries the fluid the TPRV releases to a safe location, such as a drain or a collection tank.

How does it work?

TPRVs work by releasing extra pressure and temperature from systems in a controlled way. Here’s how they work:

protect pressurized systems
Protect pressurized systems

Valve design:

TPRVs are designed with a spring-loaded valve mechanism that is held closed by the force of the spring.

Sensing elements:

TPRVs contain two sensing elements. These check the temperature and pressure levels in the system. One element is a temperature-sensing element that expands when it detects high temperatures. The other element is a pressure-sensing element that responds to high pressure.

Trigger mechanism:

The temperature or pressure levels exceed the safe operating limits of the system. Yet the sensing elements trigger the valve mechanism, which opens the valve.

Release of excess pressure and temperature:

Once the valve opens, it releases the excess pressure and temperature by discharge pipe. This prevents the pressure and temperature from building up further. This can lead to equipment failure.

Control the discharge rate:

The TPRV is designed to release excess pressure and temperature. It prevents water from discharging too quickly, which causes injury or property damage.

Reset device:

After the excess pressure and temperature have been released, the valve resets itself by closing. The TPRV is now ready to detect. It responds to any future high pressure and temperature conditions.

How to Install Temperature and Pressure Relief Valve?

Installing the temperature and pressure relief valves to proper functions is vital. It is crucial for ensuring their effectiveness and preventing dangerous coincidences. Here are some general guidelines for the correct installation of TPRVs:

Choose the right size:

The TPRV must be the correct size for the installed equipment. Check the equipment’s manual or contact the manufacturer to determine the appropriate size.

Install in the correct location:

The TPRV was installed in the correct location. You install it where it is accessible and for inspection and maintenance. It installs on the top or side of the equipment. Yet, it installs above the water level and downstream from any shutoff valves.

Use appropriate fittings: The TPRV install using suitable fittings—these threaded or flanged connections, with the necessary pipe support.

Install a discharge pipe:

A discharge pipe is installed to discharge the water from the TPRV to a safe location. These are floor drains or outside of the building. The discharge pipe is made of a suitable material and size. Moreover, it should be sloped downwards to prevent standing water.

Test and inspect:

The TPRV should be tested and inspected to ensure that it is working. The valve should be tested by lifting the lever. This ensures that water is discharged through the discharge pipe. The valve and discharge pipe inspect for signs of leakage or damage.

Following the manufacturer’s instructions and regulations is essential when installing TPRVs. This ensures that they are installed in the right way. If you are unsure about the installation process, it’s best to consult a professional.

The lifespan of the T&P Relief Valve

The lifespan of TPRV varies depending on many factors. These are the type of valve, the manufacturer, and the conditions of the system it installs. Generally, TPRVs are designed to last for many years, but they may need to be replaced if worn or damaged.

The American Society of Mechanical Engineers suggests that TPRVs be inspected and tested at least once a year. You can replace the valve every five years. Yet, this can vary based on the specific TPRV and the manufacturer’s recommendations. Regular maintenance and testing ensure that the TPRV is functioning. It helps to extend its lifespan.

TPRVs are replaced if they are not working or fail to operate during testing. A malfunctioning TPRV can lead to damage to the system. Moreover, it leads to the costly replacement of valves, which is unsuitable.

Regular maintenance, inspection, and testing are essential for any valve. This can ensure that it is functioning and can help extend its lifespan. It’s vital to follow the manufacturer’s recommendations for replacement. Replace a TPRV immediately if it is found to be defective or malfunctioning.

How to Test Temperature & Pressure Relief Valve?

It is an integral part of maintaining a safe and reliable pressurized system. Here’s how to test a TPRV:

Turn off the power supply:

Before testing the TPRV, turn off the power supply to the equipment to prevent any damage.

Check the discharge pipe:

Check the discharge pipe connected to the TPRV to ensure it is not blocked or obstructed. The discharge pipe should be clear to allow for the safe release of pressure and temperature.

pressure relief valve
pressure relief valve

Lift the valve lever:

Lift the lever on the TPRV to manually open the valve. Be careful, as hot water or steam may be released from the valve. If water is released, it should be directed towards a safe location, such as a floor drain or outside the building.

Check for leaks:

While the valve is open, check for any leaks in the valve or discharge pipe. Any leaks should be repaired before the system is put back into operation.

Release the lever:

Release the lever on the TPRV to close the valve. The valve should close and stop the release of water or steam.

Record the test:

Record the test date and any observations or findings in a log or maintenance record.

Test the TPRV at least once a year or according to the manufacturer’s recommendations. Regular testing ensures that the TPRV is functioning. This can help prevent dangerous equipment failures. If you’re unsure how to test the TPRV, consult a qualified professional.

Important Note:

The size of a TPRV is determined by the size of the pipe or its design to fit. TPRVs are available in standard sizes corresponding to the pipe size.

For example, standard TPRV sizes for residential water heaters in the United States are 3/4 inch and 1 inch. These sizes refer to the diameter of the inlet and outlet connections on the valve. Other sizes for industrial applications can range from 1/2 inch to 6 inches or larger. It depends on the specific system requirements.

Pressure and temperature ratings: TPRVs are designed to operate within a specific range. For example, a residential water heater in the United States may have a pressure rating of 150 psi—a temperature rating of 210 F.

bronze safety valve
bronze safety valve

Safety concerns;

Some preventive measure is important when you work with a water heater. It is due to the T& P relief valve damage because of high pressure and temperature. Sometimes, you find a pressure-related issue with your water heater tank. If you find the problem, hire a plumber to check the water heater.

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