- 41 -
Counter (Register): A device which indicates a quantity related to the volume measured by the meter.
Delivery, Over – Delivery, Under: The terms, over-delivery and under-delivery, are commonly used to indicate the
kind of measuring error that is experienced.
Density, Relative: The relative density t1/t2 of a solid liquid substance is defined as the ratio of the mass of a given
volume of the substance at a temperature t1 to the mass of an equal volume of pure water at a temperature t2 (this
term replaces the normal term “specific gravity”).
Differential Pressure Valve: A device designed to maintain the total pressure in a system at a desired pressure higher
than the vapor pressure of the liquid when being metered.
Digital Device: A device in which the indication of the measured quantity changes by finite increments, which may
be units, fractions, or decimals.
Digital Signal: Transmitted information that takes the form of a series of individual distinct signals. These are
commonly called pulses.
Drainage Time: The drainage time for test measures and provers shall be 10 seconds for a capacity of 10 gallons or
less, and 30 seconds for capacities exceeding 10 gallons. Necessary to achieve uniform clingage film.
Error: The difference between the indicated value and the true value.
Flow Limiting Device (Flow Control): A device installed in the system to prevent the rate of flow through the meter
from exceeding the desired maximum flow rate.
Flow Meter: Commonly used to describe a liquid measuring device that indicates the rate of flow in terms of
velocity or as units of volume per unit of time.
Flow Range: The minimum and maximum flow rates established by the manufacturer to provide the maximum
meter performance and accuracy with long life. If exceeded, accuracy or meter life may be adversely affected.
Flow Rate (Rate of Flow): The rate of flow of liquid expressed in volume or mass units per unit of time.
Gravity, Specific: See Density, Relative.
Laminar Flow: Liquid flow in which the liquid elements travel along relatively straight parallel paths.
Low Vapor Pressure Liquid: A liquid, which at atmospheric pressure and temperature can be maintained in an open
system without boiling.
Maintenance Tolerance: A tolerance test made at the maximum discharge rate that maybe anticipated under the
conditions of installation after the initial acceptance testing has been successfully completed.
Master Meter: A meter used as a reference for testing other working meters.
Meniscus: The curved surface at the end of a liquid column.
Non-return Valve (Check Valve): A device designed to prevent a reversal of flow.
Normal Test: A test made at the maximum discharge rate that may be anticipated under the conditions of
installation. (If equipped with an automatic temperature compensator, the meter should be tested with the
temperature compensator deactivated.) Any additional test conducted at flow rates down to and including one-half
of the sum of the maximum discharge flow rate and the rated minimum discharge flow rate shall be considered
normal tests.
To Next Page
Loading...