Air eliminators are placed in the line on the intake
side of the meters. It consists of a cylinder usually 14 inches to 20
inches in diameter, containing baffles that are designed to force the
flow of fuel to the bottom of the cylinder and to force 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.
The flange gaskets should be checked daily for leaks. The diaphragm
valve should be checked daily to ensure it is working properly or to be
replaced if needed. Remove any rust and paint.
PART C - PROVING DEVICES
Prover tanks. There are several types of provers available for
proving meters. They are primarily tanks or piping of a known volume.
When they are filled, the known volume is compared to the metered
volume (unknown). Prover tanks normally range in size up to 600
Five gallon prover. The 5-gallon prover is used for proving small
meters on tank trucks and at service station type installations.
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 trailer-mounted.
Open volumetric prover. Open provers can be trailer-mounted or in a
fixed installation. They consist of the tank, the neck of the prover,
a splash dome, overlapping site gage glasses, and a gage glass scale
in the neck of the prover. Thermometers are at the top and bottom.
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.
PART D - VERIFICATION REQUIREMENTS
Meters must be verified based on the following factors:
Size of Meters (GPM)
Total Gallons Measured
600 and over
Meters will be calibrated at least every 12 months or whenever the meter
is suspect, whichever comes first. The meter must be within .0025 (1/4
gallon) for every 100 gallons registered by the master meter. If the