Breather Valve Manufacturer

Breather Valve

Some particular types of valves are available in the market, which are fitted as a safety device to avoid catastrophic failure of tanks and enclosed vessels. One such valve is the breather valve. Unfortunately, major accidents happen when these devices fail to perform.

In this article, we shall discuss in brief Breather valves, their function, types, installation, maintenance, advantages, and disadvantages. I am sure, by the time you finish reading the article, you will have a brief idea of what kind of breather valve you are looking for.

So, let’s start with some basics.


What Is a Breather Valve?

Breather valves are a special type of relief valve designed explicitly for atmospheric or low-pressure tank protection. They are also known as Direct Acting Pressure/Vacuum Relief Valves.

These valves are primarily used on bulk storage tanks, including the fixed roof storage tanks with floating cover to minimize losses due to evaporation. In addition, these valves prevent any excessive pressure or vacuum condition within the tank, which minimizes the risk of imploding or exploding of tanks due, thus saving significant loss of equipment or system failure.

The vacuum or pressure levels within a tank are controlled using a weighted pallet or spring mechanism in the breather valves. The combination of a pallet and spring mechanism is most commonly used. Spring is used for pressure relief setting, while the weighted pallet is used for vacuum relief setting.


How Does A Breather Valve Work?​

The working of a breather valve is very easy and simple to understand. It has two valves placed either side by side or in overlapped position. One of them is called the In-breathing valve, and the other one is called the Out-breathing valve.

Let us consider a case where the tank’s pressure rises above the set pressure due to the loading of fluid in the tank or heating of the fluid during the daytime. As the pressure exceeds the set pressure, the Pressure valve operates, and the excess pressure is released, and atmospheric pressure is restored in the tank. This process is called Out breathing of the breather valve.

Now let’s consider another case where the tank pressure falls below the atmospheric pressure due to the discharging of cargo or cooling down of the fluid and settling of cargo vapors during the nighttime. In this case, the partial vacuum is created in the tank. Here the vacuum valve is operated, and the atmospheric air is let in to revive the tank pressure back to normal (i.e., atmospheric pressure or below set pressure of the vacuum valve). This process is called In the breathing of the breather valve.

These two valves within a breather never work simultaneously. However, when one of the valves operates, the other provides a good sealing effect due to the adsorption effect on the side of the seal.

The in-breathing and out-breathing processes stop when pressure or vacuum in the tank restores to normal, and both the pressure and vacuum valves are closed.

Valve chatter is very fast and frequent opening and closing of the pressure or vacuum valve. This accelerates seat and diaphragm wear. If less than 20% deviation of pressure or vacuum is allowed, the usual working pressure chattering occurs in the breather valve. Therefore, it is essential to understand that a Pressure/Vacuum Valve does not function exactly like a high-pressure safety Relief Valve and should not be set at 10% or 20% overpressure.

Types Of Diaphragm Valve

Straight Through Diaphragm Valve

The straight-through or the full-bore diaphragm valve is similar in appearance to the weir-types; but, it does not include the typical raised weir or saddle and instead has a completely straight flow path. This enables the fluid to pass through the valve freely without any significant obstructions.

The membranes of these valves are usually more flexible and allow greater travel distance, as they have to make contact with the bottom of the valve. However, due to the flexible design of membranes, these valves need more maintenance in comparison to the weir-type valves.

This kind of valve is often utilized in slurries, viscous fluids, and other applications where blockage must be minimized. These valves can be easily cleaned in place using steam or caustic soda without the need to remove them from the pipeline.

Weir Type Diaphragm Valve

The weir-type valve is one of the most common design of diaphragm valve used for small flow control with leak-proof operation. It is also referred to as a saddle-type diaphragm valve.

The weir-type has a raised lip on the body, which acts as a valve seat. The diaphragm comes into contact with the weir during valve operation to control the flow of fluids. In addition, the raised weir helps to reduce the diaphragm movement between the fully open and completely closed positions. This lowers the amount of stress and strain placed on the diaphragm during this process.

The valve design is ideal for hazardous or corrosive liquid and gas, as any membrane failure can be easily contained within the bonnet. Because of the self-draining characteristic of the valve body, they are also recommended for food processing applications.

Common Standards For Breather Valve

• DIN EN 14595: For Tanks used to transport dangerous goods-service equipment for tanks-pressure and vacuum breather vent.

• API 2000: For the purpose of the Venting of Atmospheric and Low-Pressure Storage Tanks.

• API 2521: Pressure-Vacuum Vent Valves which are used for Atmospheric Loss

• API 2513: Minimum Evaporation loss in the Petroleum Industry-Causes and Control

Types Of Breather Valve

  1. Pressure And Vacuum Relief Valve:A composite pressure vacuum breather valve is used to prevent overpressure or vacuum conditions. It consists of two independent units, one to control pressure and the other to control vacuum.
  • Tank Blanketing Valve:Wherever the constant pressure is to be maintained in the vapor space of the storage tank during tank unloading or vapor under condensation due to low ambient temperature, Tank blanketing valves are used.
  • Emergency Vent Valves: In case of fire or emergency, the surrounding temperature changes very rapidly so do the pressure inside the storage vessel. The emergency vent valve maintains positive pressure in the tank within allowable design parameters, thus reducing fire within the tank. This type of valve is used as a standby device installed along with a breather valve to safeguard the tank in emergencies.
  • Gauge Hatch:This type of breather valve is similar to the emergency vent valve and is used to carry out manual measurement of tank level with a metallic tape in cases where the conventional float and tape type-level measurement device is out of action. This type of breather is generally installed as a standby measure on the top of storage tanks.
  • Pilot-Operated Relief Valve:This type of breather valve is mainly used to protect from low pressure or vacuum situations. The pilot-operated relief valves provide accurate, safe, and dependable protection. With proper adjustment set pressure in this type of valve, up to 95% of bubble tightness of the Pilot operated relief valve can be achieved.
  • Air-Operated Relief Valve:This type of breather valve is very popular in the petroleum and chemical industry because it reduces evaporation loss of highly volatile substances. A pressure switch coupled with a solenoid valve and usage of control air provides a bubble-tight seal. This reduces the effect of corrosion or polymerization on the seat, which would have been the case if vapor pressure was the operating medium. Therefore, these valves have very high efficiency and require very little maintenance.

Materials For Breather Valves

The following materials are used to manufacture breather valves with respect to the fluid vapors it will be exposed to during its normal operations.

  • Carbon Steel
  • Aluminum
  • Stainless Steel
  • Cast Iron

However, breather valves can be manufactured using any material depending on service conditions.

Advantages Of Breather Valve

 Breather valves have the following advantages:

  • They prevent the vacuum and pressure from exceeding the tank design limits, thus protects the tank from imploding or explode.
  • These valves protect the tank contents from moisture intrusion.
  • They reduce the vapor loss from the storage tank.
  • Breather valves enhance the safety of the tank and prevent Fire Hazards
  • Breather valves are Low maintenance valves.
  • Boosts the pump operation by maintaining a higher suction head.

Disadvantages Of Breather Valve

Some of the disadvantages of breather valves are

  • Failure to operate may have severe consequences.
  • A too significant difference between (i.e.,>3 psi) the pressure and vacuum setting increases the overall manufacturing cost.

Breather Valve Selection Guide

The breather valve selected must be capable of restricting the moisture that could enter the container. The basic purpose of these valves must protect the container or the tank from excessive pressure and vacuum conditions. Thus, the breather valve must remain sealed except during its operation and in extreme temperature conditions. Certain important factors must be taken into consideration while selecting a breather valve.

  • The design as well as Maximum operating pressure and vacuum of the tank.
  • The volume of the tank
  • The pressure gradient with respect to the time taken.
  • The temperature variation during the operations and storage
  • Relative humidity and temperature of the storage area

Where Is The Breather Valve Used?

Breather valves find their application in almost all industries involved in fluid storage. Liquids and chemicals are stored in large quantities in big tanks for transportation and use in various sectors. The storage of fluid is an essential part of every industry. Be it,

  • Food Processing Industry
  • Chemical Industry
  • Petroleum industry
  • Marine Industry
  • Pharmaceutical Industry
  • The textile industry, and many more.

It is particularly useful in the petroleum and chemical industry. High volatile liquids are stored and transported without any loss or wastage of cargo in the form of vapors to the atmosphere, simultaneously taking care of all safety standards.

How To Install A Breather Valve?

The breather valve must be installed at the highest point on the tank top to reduce evaporation losses and other exhausts. This will ensure direct and maximum access to the breather valve. Generally, the Breather Valve is mounted on a nozzle opening of a fixed roof atmospheric storage tank.

A fixed roof atmospheric storage tank does not contain any controlled opening. So, there are high chances of rupture during the pumping of fluid into or out of the tank due to a sudden change in the vapor pressure. Similarly, in cases of thermal change in the fluid.

The breather valves are provided with a nut, gasket, and washer in general so that they can be mounted through a hole on a flat surface. At the time of installation, certain key factors must be considered, such as mounting hole diameter, installation torque, and the thickness of the valve.

Maintenance Of Breather Valve

Inspection and maintenance of the breather valves should be carried out periodically as per the planned maintenance system. It is essential to follow the manufacturer’s guidelines as these valves come under safety equipment. The following steps shall guide you in the maintenance of these critical valves.

1. Verify and record nameplate information and be sure to protect the nameplate while servicing the valve. This will preserve the important information about, make, type, and settings of the valves.

2. Dismantle the valve and check the condition of both pressure and vacuum valve and seat.

3. Check the rubber gasket and seals and replace them with original spares if necessary.

4. Visually inspect each part carefully during disassembly. This should be carried out per manufacturer instructions.

5. Proper cleaning of parts is very important for trouble-free operation but avoid aggressive cleaning methods which may damage delicate or highly machined surfaces.

6. The manufacturer’s instructions for assembly must be strictly adhered to.

7. Testing and certification of these valves are carried out only by a certified person and on approved testbeds.

8. In case of replacement of parts due to damage, only original parts approved by the maker shall be used.


Although the operation of breather valves is not restricted to tank or vessel safety and relief, Knowing which one is right for which application is critical to all end-user industries. Thus, a client should consider all the aspects related to the selection of a breather valve for a particular purpose.

I hope you got a brief knowledge about breather valves. Do inform us about your query in the comment section. We shall guide you to choose the perfect valve as per your requirements.

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