Scope
This Guideline provides a method to ensure that newly installed liquid
densitometers are functioning correctly. There are two circumstances
under which densitometers are changed out:
a) The densitometer service time period has expired.
b) The installed unit is malfunctioning.
Confirmation that the newly installed densitometer is functioning correctly
is achieved by comparing density readings to density values determined
by laboratory analysis.
Frequency: As needed
LIQUID DENSITOMETER CHANGEOUT PROCEDURE
PREPARATIONS:
If stable density 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. The manual value of density
shall be determined by laboratory analysis or, if checked by
comparison to laboratory analysis within the previous week, by input
of the value of density indicated by the densitometer currently in
service.
Give a brief description of the test in the Metering Log Book.
Record the results of this test on the Liquid Densitometer Changeout Test Sheet, attached.
Ensure
the oil densitometer to be installed has a valid calibration
certificate and that the serial number on the certificate corresponds
with the densitometer. Ensure that the serial and tag numbers are
recorded on the test sheet.
Ensure that the Liquid Densitometer Air Check procedure FMT 014
is completed on the replacement densitometer at time of installation.
PROCEDURE:
The oil densitometer shall be changed using the following
procedure: –
a) Note the current value of density from either laboratory
analysis or the installed densitometer (provided this unit have
successfully been compared to laboratory analysis within the
last week). Select this keypad value as the value in use.
b) Close and lock the inlet and outlet isolation valves to the
densitometer being replaced.
c) Open the drain and vent valves associated with the
densitometer.
d) Electrically isolate, disconnect and remove the field cable at
the densitometer.
e) Remove the bolts from the top and bottom densitometer
flanges and remove the unit.
f)
Install the replacement densitometer tightening up evenly on
top and bottom flanges.
g) Re gland and terminate the field cable into the replacement
densitometer.
h) Power up the densitometer and perform the Liquid
Densitometer Air Check as described in procedure FMT 014.
i)
If the air test is successful, close the drain and vent valves
and unlock and open the inlet and outlet isolation valves on
the densitometer.
j) Enter the new densitometer constants into the appropriate
stream flow computer.
k) Update the flow computer configuration sheets as per
procedure FMT 002.
l) Read the density value from the newly installed densitometer
and compare it with the in use keypad value. It should agree
with acceptable tolerance.
m) Remove the keypad value from the flow computer and select
the installed densitometer value as the in use value.
n) Enter details of all tests in the Metering Log Book. Record
that the densitometer has been replaced and the serial
number of the replacement unit. Return the densitometer that
has been removed from service to a re-certification agency.
LIQUID DENSITOMETER CHANGE OUT TEST SHEET
