Breather Valves

• Direct-acting pressure/vacuum relief valves are special types of safety valves specifically designed for tank protection.
• The product range includes pressure-only, vacuum-only, and combined pressure/vacuum valves, available with flanged connections or vented to atmosphere.
• These valves are widely used on bulk storage tanks, including fixed roof tanks with floating covers, to minimize evaporation losses.
• They prevent excessive pressure or vacuum build-up that could unbalance the system or damage the storage tank.

Why Use Breather Valves

• A breather valve is a protection device installed on the nozzle at the top of a fixed-roof atmospheric storage tank.
• Its primary purpose is to protect the tank from rupture or implosion.
• During material transfer, pressure inside the tank may increase or decrease, requiring the tank to “breathe” to maintain safe pressure levels. Hence the name breather valve.

How Breather Valves Operate

• When the tank pressure is equal to atmospheric pressure, both the pressure (exhalation) valve and vacuum (inhalation) valve remain closed.
• When the tank pressure exceeds atmospheric pressure:
  → Internal pressure lifts the valve disc against gravity → the pressure valve opens → gas is released → pressure is balanced.
• When the tank pressure drops below atmospheric pressure (vacuum condition):
  → Atmospheric air enters through the vacuum side → lifts the valve → the vacuum valve opens → air flows into the tank → pressure is balanced.

How Breather Valves Protect

1. Pressure & vacuum settings
2. Temperature variations:
   • The frequency of valve opening depends on both the valve setting and temperature fluctuation levels.
3. Temperature vs. humidity:
   • Each valve opening introduces moisture into the tank, affecting the life of desiccants.
4. Number of breathing cycles

Selecting the Right Valve

• Maximum pressure/vacuum the tank can withstand without leakage or deformation
• Effective tank volume
• Rate of pressure change during operation

Advantages of Breather Valves

• Reduces product evaporation → cost saving
• Enhances fire safety
• Protects tanks from pressure and vacuum damage
• Reduces corrosion and emissions
• Improves safety during pumping operations
• Low maintenance cost

Simple summary: A breather valve operates like two safety valves installed in opposite directions—one for inward flow and one for outward flow. When the tank reaches the preset vacuum or pressure limit, the valve opens to allow air in or out, protecting the tank from damage.

Video about How Does Breather Valve Work?