The air release valves shall maintain closed position to prevent the loss of water by the positive seating of a non – corrosive float against a smoothly ground contact surface of the exhaust orifice. It shall automatically provide for the special ball float moves away from the orifice seat. The float shall be free floating within the valve body, linkages or evers attached to the float are not acceptable. The body of the valve shall be cast iron.

INSTALLATION

Once in the system, air will tend to collect at summits in the pipeline and points where the pipe slops changes. Just as important as the proper selection o air release valves is the proper location and installation. Air pockets are generally found just downstream of the area where they are first suspected due to the velocity of the fluid. As a general rule required location of air release valves may be seen by
referring to the drawing. A careful study will show that there is an air release valve at every change in the pipeline slope with the exception of the extreme low points.

WHY INSTALL?

ECONIMICS – To ensure that a pumping system will operate in the most efficient manner, care must be taken to ensure that trapped or entrained air is not robbing the system of the efficiency that the designer originally intended.

The presence of tapped air pockets can seriously reduce the carrying capacity of the line. In fact, air binding can completely stop the line flow. Air binding in pipelines requires additional power expenditures which can substantially increase the pumping costs. Thus, the proper application and selection of air release valves becomes an investment bringing immediate returns without major cost considerations.

AIR ENTRY

There are numerous ways in which air can enter a pipeline. A few common ways are:
 
1. Air that is in the line before the line is filled and not completely purged.
2. Well pump installations without air release valves can on startup add considerable air to the pipeline.
3. Air may be drawn in at intakes, for example, by the vortex action at a pump suction.
4. Air may be drawn into the line at leaking joints or glands.
5. Air in solution is released at high points in the line or at points of pressure reduction such as throtted valves or other restrictions.