(1) Description and uses. Air eliminators are placed in the line on the intake side of the meters. It
consists of a cylinder usually 14 to 20 inches in diameter containing baffles that are designed to force the flow of
fuel to the bottom of the cylinder and air to the top. On the top of the cylinder is a diaphragm float-activated
valve. The float holds the valve open allowing air and vapors to escape to the atmosphere. When all air is
removed, the float rises in the product and closes the valve.
(2) Maintenance. The flange gaskets should be checked daily for leaks. The diaphragm valve should
be checked daily to ensure it is working properly and replaced if needed. Remove any rust and paint.
Provers are used in any installation where you have to calibrate meters in pipelines, loading docks, and dispensing
areas. The maintenance of meters is very limited. Check for dents or distortions and make sure the sight gages
are in good working order. Make sure the thermometers are certified.
a. Proving cans. (Field Standard Test Measure) A small meter can be verified by running fuel through
the meter into a 5- or 10-gallon graduated can or a proving tank which holds an exact amount of fuel.
b. Mechanical displacement provers. These provers have a calibrated continuous loop and a spheroid.
The sphere displaces a known volume from the number one sensor to the number two sensor, and the amount
displaced is compared to the meter reading. You will find this kind of meter in fixed installations or they may be
c. Open volumetric prover. The open prover can be trailer-mounted or in a fixed installation. They
consist of the tank, the neck of the prover, splash dome, overlapping site gage glasses, and the gage glass scale in
the neck of the prover. Thermometers are at the top and bottom. The open volume prover was once the field
standard prover for Army petroleum facilities. Since IPDS was fielded, this prover is no longer used.
a. A typical meter installation would be set up as follows:
(Direction of flow) > (items in order) a-b-c-d.
(3) Air eliminator.