Scope
This Guideline provides a method to check that the meter and meter
prover RTD temperature inputs are functioning correctly. This is
achieved by applying known resistances in the ‘field’ and comparing
the expected temperatures to the displayed temperatures.
RTD TEMPERATURE INPUT CALIBRATION | PROCESS & CONTROL SYSTEM
Procedure
PREPARATIONS:
If stable temperature conditions exist, and a manual value can
be input at the flow computer, then this test may be performed
with the metering stream in service. Otherwise ensure that the
meter stream is off-line and out of service.
Give a brief description of the test in the Metering Log Book.
Record the results of this test on the RTD Temperature Input
Calibration Test Sheet, attached.
Verify that the certificates for the test equipment are valid.
Check that the test equipment serial numbers and certification
dates are accurately recorded on the test sheet and
correspond with the test equipment used.
Ensure the instrument tag and serial numbers are recorded
on the test sheet.
CALIBRATION EQUIPMENT:
A) Resistance Box
B) Digital Multi-meter
PROCEDURE:
Disconnect the RTD leads at the temperature transmitter terminals.
a) Connect the resistance box to the RTD input terminals at
the temperature transmitter.
b) Connect the digital multi meter at the transmitter field input
terminals at the back of the panel in the control room, to
monitor the 4 to 20 mA current input, or in parallel across
the 250 ohm input resistor, to monitor the 1 to 5 volt input.
c) Using the resistance box, apply resistance values to the
transmitter at the following nominal points on its span, with
both rising and falling resistance: OYO, 25%, 50% 75%
and 100%.
d) Complete the temperature transmitter test sheet. Record
the current 1 voltage at the Digital Multimeter and the
temperature reading at the flow computer.
e) If the calibration check is within the acceptable tolerance of
+I 0.25 ºC the test is complete.
f) g) If the calibration check is out of tolerance transmitter
adjustment is required.
g) Adjust the zero and span to calibrate the transmitter then
repeat step d).
h) Complete the temperature transmitter test sheet, re-instate
the loop and return to service.
i) Enter details of all tests in the Metering Log Book.
TEMPERATURE TRANSMITTER TEST SHEET
