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Temperature Correction
If the conditions of testing are such that there will be a change of more than a few degrees in the
temperature of the liquids between the time it passes through the meter and the time the prover is
read, it will be advisable to make a temperature correction to the prover readings. To do this, it is
necessary to install thermowells; to take readings of the temperature of the liquids in the meter
and in the prover; and to take the degrees API of the liquid. Corrections can then be easily made
by the use of the National Standard API Tables.
PRODUCT DEPLETION TEST (SPLIT COMPARTMENT)
Purpose: A product depletion test verifies the proper operation of air elimination when the
storage tank for the product being measured is pumped dry. This test is necessary for meters that
may drain a tank completely, such as a vehicle tank meter.
Multiple-Compartment Test Procedure:
1. Begin the test from a compartment (ideally the largest compartment) containing an amount of
fuel equal to or less than one-half the nominal capacity of the prover being used. Operate the
meter at the normal full flow rate until the compartment is empty. There are several methods for
determining that the compartment is empty. There may be a significant change in the sound of
the pump. There may be visual evidence that the compartment has run dry. The meter may stop
entirely or may begin to move in jumps (pause, resume running, then pause, then run again.)
2. Continue the test until the meter indication stops entirely for at least 10 seconds. If the meter
stops for 10 seconds or more, proceed to step 3. If the meter indication fails to stop entirely for a
period of 10 seconds, continue to operate the system for 3 minutes.
3. Close the valve from the empty compartment, and if top filling, then close the nozzle or valve
at the end of the delivery hose. Open the valve from another compartment containing the same
product. Carefully open the valve at the end of the delivery hose. Pockets of vapor or air may
cause product to splash out of the prover. The test results may not be valid if product is splashed
out of prover. Appropriate attire and protection is required, but caution is still necessary.
4. Continue delivering product at the normal full flow rate until the liquid level in the power
reaches the nominal capacity of the prover.
5. Close the delivery nozzle or valve, stop the meter. Allow any foam to settle, then read the
prover sight gauge as quickly as practical.
6. Compare the meter indication with the actual delivered volume in the prover.
7. Calculate the meter error, apply Product Depletion test tolerance, and determine whether or
not the meter error is acceptable.
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