Total Control Systems 700-20 Engineering Manual page 43

Positive Displacement Meter: A meter in which the primary sensing element separates the liquid into measured
segments of know volume providing a shaft motion or other signal that can be used for indicating the volume
delivered.
Preset Device: An indicating device that can be preset for a desired quantity which will stop the flow automatically,
or provide a signal when the preselected quantity of liquid has been metered or "delivered".
Pressure Loss (Pressure Drop) (Loss of Head) (Differential Pressure): The difference in pressure between the inlet
and outlet of a device while operating.
Prover (Proving Tank): Volumetric Type. A closed or open vessel designed especially for accurate determination of
the volume of a liquid delivered into or out of it during a meter run. The volume of liquid is either observed from
the liquid level in a gage proving glass or known from previous calibration of a fixed-volume vessel. The volume is
greater than ten gallons. See Test Measure.
Recording Element: A device designed to print the volume metered on a ticket, slip, tape, or card.
Reference Standard: A volumetric measure that has been verified to "contain" or to "deliver" a known volume and
which is used for establishing the volume of field and working standards.
Register (Counter): A device, which indicates the quantity measured by the meter.
Registration, Over – Registration, Under: The terms, over-registration and under-registration, are commonly used to
indicate the kind of measuring error that is experienced. Over-registration indicates the counter is registering a
greater volume than is delivered by the meter, and under-registration indicates that the meter is delivering more than
is registered on the counter.
Repeatability: A measure of the deviation as a series of test results from their mean value, all determinations being
carried out under identical conditions.
Special Test: Any test other than a "Normal" test. A special test is defined as a test "to develop the operating
characteristics of a liquid measuring device and any special elements and accessories attached to or associated with
the device. Special test of a measuring system shall be made at a minimum discharge rate of 20% of the marked
maximum discharge rate or at the minimum discharge rate marked on the device whichever is less.
Split Compartment Test: A test applied to a truck mounted metering system, which simulates the conditions
encountered in actual operation when one truck compartment is emptied during a delivering and the delivery is
completed from another compartment.
Strainer (Filter): A device equipped with a porous medium or wire mesh element to prevent particles of foreign
material from passing through a meter.
Test Measure: Vessels designed especially for the precision measurement of liquid having verified capacities of 1, 5,
or 10 gallons. These are usually certified for accuracy of measurement by the National Bureau of Standards.
Tolerance: The amount of error that will be allowed. It is a plus of minus value.
Torque Load: The power required of the meter for driving accessory equipment such as counters, printer, etc.
True Value: The theoretically correct amount. In every day use it is represented by the Standard being used for
comparison.
Vapor Eliminator (Vapor Release): A device installed upstream of the measuring device to avoid measuring air
and/or vapor.
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