Atec Wallace-Tierman-65-120 - Manual (Page 3)

The W&T Portable Calibrator eliminates the need for
special arrangements or external controls. The carry-
ing case has a compartment for adapters, tubing, and
other accessories; the case cover is easily removed.
Complete information on the use of the calibrator is
given in an instruction book. A schematic flow dia-
gram on the panel shows the calibrator’s connections
at a glance.
USES OF THE W&T PORTABLE
CALIBRATOR
Simplest use of the calibrator is to carry it to an on-
stream gauge, indicator, or recorder. Calibration of
such instruments can be quickly checked by making
simple connections without taking the instrument out
of service. Also, the calibrator can simulate the set
and process-variable signals to a pneumatic control
device and check its output. These three pressures
can be read out and checked in any order and in
rapid sequence. By evacuating the calibrator, abso-
lute pressure measurements can be made.
PUBLICATION
TI 650.504DE
Calibrator Uses
3
Calibration of a pressure transmitter
Using a common supply pressure for both the cali-
brator and the transmitter, transmitter input is
regulated to the desired value and held. Transmit-
ter output is accurately indicated by the calibrator.
Calibration of a gauge, indicator or recorder
Test pressure is applied to the instrument and to
the calibrator simultaneously. Instrument and cali-
brator readings are compared for an accuracy
check.
Calibration of a differential pressure transmitter
The transmitter’s supply and high-input pressures
are regulated to the desired values and held.
Transmitter output is indicated accurately by the
calibrator.
Calibration of a typical stacked diaphragm
pneumatic controller
Controller supply pressure is regulated to the de-
sired value and held. Controller set and measured
inputs and output A are regulated to the desired
value and held. The calibrator then reads out con-
troller output accurately. P
3
equals P
2
for any value
of P
2
if the controller is in calibration.
Calibration of a ratio relay
The ratio relay’s input and reference pressures are
regulated to the desired values and held. Relay
output is indicated accurately by the calibrator.
Pressure
Transmitter
3-15 psi output
Air supply P
1
P
3
Input
Regulator
Supply
Regulator
500-psi gauge
supply
(May also be connected to P
2
)
Air supply
P
1
Low pressure input (atmosphere for test)
Differential
pressure
transmitter
supply
Air supply
High pr
essur
e input
3-15 psi output
P
1
P
2
P
3
Supply
Set
Input
Output A
Output B
Measured
Input
Air supply P
1
P
2
P
3
Output
Reference pressure if required
Air supply P
1
P
2
P
3
Ratio replay
Supply
Input