Air Release Valves

Air release / relief valves should be used on piping systems to remove air pockets which can prevent water flow, cause water hammer and cause problems with the the performance of control valves and other fittings. Air valves have two functions or types:

• Kinetic Air Valves are used to release the air as lines are filling with water. They allow high volumes of air to be released, but close when the line reaches pressure. They also allow air back into a line when it is draining to prevent pipes collapsing. It is important that the air release rate of the air valve is greater than the fill rate of the pipe. -
• Automatic Air Valves are used to release air from pipes under pressure. Air can get into pipes even when they are are completely closed due to the air which is dissolved in water (2% at 1 atm). It is important to release this from pipe under pressure.
  
• Combination Air Valves incorporate both of the above functions Air valves should be put at the end of lines which are filling and draining and at any high points in the lines.

It is recommended to put an air valve periodically along long pipelines. Air valves come in a range of pressure ratings so it is important to select a valve appropriate for your system pressure rating. Note that air valves also have a minimum system pressure rating which for the Bermad Air valves below is 0.1 bar.