Appendix A Glossary

Page A.3

Degree Brix A unit on an arbitrary scale which can be converted into actual SG
values. Used when describing the sugar content of aqueous solutions.
Density The measured density of the fluid in a pipeline.
Differential pressure The difference in pressure at two points in a pipeline.
Digital to analogue converter A circuit that converts digital signals into analogue equivalents. See
also Analogue to digital converter.
Download T o send data or programs to another (usually subsidiary) instrument.
(Opposite of Upload).
DP See Differential pressure
E
EMC Electro-Magnetic Compatibility
Event A change in the system operation. Events may be caused by the user
(such as setting a parameter or changing the security) or by alarms (if,
for example, a fallback is invoked when the system fails).
External connection A generic term which covers: inputs, outputs, power supplies and serial
communications; in short, anything connected to the 7951.
F
Fallback mode A description of the system when it is using a Fallback value.
Fallback value A value used as a temporary substitute for a parameter when a live
input which is used to calculate the parameter fails.
Flow computer An instrument which monitors flow rates and densities of gases and
liquids. It does this by communicating with transmitters such as
pressure, temperature, level, flow, density and analytical instruments.
These measurements are then corrected for temperature, pressure and
velocity of sound.
FS Full scale.
Full composition The composition of a gas used in calculating energy and
compressibility.