Differential valves are placed on the meter outlet and work in conjunction with the air eliminator to stop the flow of product through the meter until the air/vapor is removed.
To do this, the air eliminator and the differential valve are connected during installation. Differential valves are normally closed, but when the pump starts and pushes fluid through the system, the differential valve spring gives way to flow pressure.
In order to keep the differential valve closed when air or vapor is expelled from the air eliminator, vapor is routed through the piping to the rear of the differential valve spring.
The combined force of the vapor pressure and the spring force keep the differential valve closed until the vapor is removed by the air eliminator.
Materials of construction: Aluminum.