Yokogawa digitalYEWFLO (DY) - Manual (Page 108)

GLOSSARY OF TERMS
IM 1F2B4-01-YIA
Page 103
VII. GLOSSARY
ACF: actual cubic feet - The volume which a gas occupies at any given temperature and pressure.
The mass of that volume will vary with the changes in the pressure and temperature.
Amplifier assembly - An electronic device which receives an input signal (in the case of YEWFLO
frequency of vortex shedding) and controls the output signal such that the output is proportional to the
input signal. In the case of YEWFLO this could be either an analog (4-20 mA) signal or frequency
proportional to flow rate.
Bluff body - The non-streamlined obstruction placed in the flow stream for the purposes of generating
vortices. Also know as the shedder bar.
BRAIN™ communication - The communication protocol for all Yokogawa Smart products. The
communication signal is a Frequency Shift Key (FSK) signal superimposed on the 4-20 mA output
signal. The frequency is high enough (2400 Hz) that it does not interfere with the 4-20 mA signal and
therefore digital communication is transparent to other devices on the signal wires, like recorders or
controllers etc.
BT100 - The hand held BRAIN terminal (2 line alphanumeric display) which allows a user to
communicate with any of the Yokogawa BRAIN products via the 4-20 mA signal wires. Note: When
the YEWFLO is set in the Pulse mode, the BT100 must be connected directly to the connection points
on the amplifier circuit board.
BT200 - An enhanced version of the BT100 above. The BT200 has an 8 line display, optional printer,
and programmable function keys that further simplify the use of the BRAIN protocol.
Check data - The “G” portion of the YEWFLO parameter Menu used to obtain real-time data on what
is happening in the pipeline. Such as instantaneous frequency, or flow velocity etc.
CLR ALM - This function (parameter H10) will allow you to deactivate the overspan alarm and in
ignore the over-range span setting error, if you chose to set a span in excess of the nominal maximum
flow,. When setting the span value into Parameter B52 the Alarm will indicate if you have set a value
in excess of the nominal max for meter size selected. For instance, if you input a liquid flow span such
that the velocity is greater than 32 feet per second this alarm will be triggered and will display on the /
TBL local indicator. Setting either the span or the meter size incorrectly will cause this alarm.
Resetting one of these settings will eliminate the overseen alarm.
Compressibility - The ability of a substance to expand or contract in volume when acted upon by
either temperature and/or pressure. Gas are considered compressible whereas liquids are normally
considered non-compressible. The extent to which a gas will expand or contract is defined by the
perfect gas law. The perfect gas law is a good tool for estimating density of a gas at different
pressures and temperatures. Most gases do not follow the perfect gas law exactly, and each gas
therefore has a compressibility factor that defines how it will deviate from the perfect gas law. The
compressibility factor must be looked up in a reference book or computer program for the specific gas
in question. Note: for Natural Gas, the American Gas Association (AGA) provides data on the
variable F
pv
. The compressibility factor for YEWFLO is defined as 1/(F
pv
) 2 , this value is used for
sizing and setting the software parameters.
CPU (central processing unit) - This is the portion of the electronics which manages the control of all
circuits, computation, communications and outputs. Also know as the microprocessor.