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Appendix A Glossary
Page A.2
Calibration certificate
Each transducer is calibrated before it leaves the factory. The details
(together with the transducer’s serial number) are recorded on a
Calibration Certificate.
Calibration constant
Among the information given on the calibration certificate are some
constants (unique to that transducer) which compare the transducer’s
actual performance against a standard. The signal converter must
know these constants before it can calculate accurate results.
The constants are designated: K0, K1, K2, and so on.
Calorific value
The energy content of a substance (usually a gas).
Chassis earth
In a large installation where the chassis and instrumentation are
earthed separately, this is the “dirty” earth to which instrument chassis
are connected.
Checksum
In data transmission, a checksum is a number which is added to a
string of data and whose value is related to that data. It is used to
check that the data has been transmitted accurately.
Connector
The part of a cable that plugs into a port or interface to connect one
device to another. Most connectors are either male (containing one or
more exposed pins) or female (containing holes in which the male
connector can be inserted).
Configuration
1. The setting up of an instrument (by entering data, setting fallback
values, setting alarms, and so on) so that it works according to your
requirements.
2. The method by which transducers and other inputs and outputs are
physically connected to the 7951
Conventional pipe prover
This has a volume between detectors that permits a minimum
accumulation of 10,000 direct (unaltered) pulses from the meter under
test.
Crystal factor
A multiplying factor which accounts for the difference between the
actual frequency of a particular crystal and its theoretical frequency.
CV
See Calorific value
D
DAC
See Digital to analogue converter
Damping
Suppressing the oscillations in a vibrating body or medium.
Degree API
Used in the petroleum industry to describe the density of petroleum
products. A degree API is given by:
141.5/(SG at 60
o
F) - 131.5
Values lie within the range -1 to +101, the larger the number the lighter
the oil.
Degree Baume
A unit on an arbitrary scale which can be converted into actual SG
values. Used when describing the sugar content of aqueous solutions.