B-320-2-E
25
8.3 Operation with Actual Flow
At first-time operation with actual process fluid, careful observation of operations sequence which is described
below is required. It is essential that the flowmeter be used within the specified flow range.
(
⇩
Refer to the piping diagram below.)
SHUTOFF
VALVE
BYPASS LINE
FLOW
METER
STRAINER
VALVE
FLOW DIRECTION
A
B
C
Fig. 8.1
(1) Shut off the valve (A) on the inlet side and the valve (B) on the outlet side and then open the bypass line
valve (C) to allow the fluid in the bypass line, thereby removing weld chips, scale and other foreign solids
left in the piping assembly.
CAUTION: This is particularly important in a newly installed piping assembly.
(2) Open the shutoff valve manually. If it is hard to open it manually, set the missing pulse setting to "0", select
any batch setpoint and press the START button.
(3) Carefully and slightly at first, open the valve (A) upstream of the meter progressively and then, slightly at
first, open the valve (B) downstream of the meter progressively.
(4) Slowly close the bypass line valve (C) and make sure that the total counter in the register advances in
response. Maintain a flowrate 10 to 20% of the maximum flowrate in this state, allow the flow to run for
more than 15 minutes and make sure that air in the piping assembly has totally escaped.
In applications where temperature exceeds 60°C, run the system at least for 30 minutes in this state to
ensure uniform heat distribution in the measuring chamber (preheating is necessary).
(5) Following the break-in (preheating) period, shut off the bypass line valve (C) completely and open the
upstream valve (A) progressively until fully open and slowly open the downstream valve (B) until the rated
flow is reached.
(6) Flowrate should be regulated with the valve (B) downstream of the meter and should be held within the
specified rating.
8.4 Operating Precautions
(1) When changing flowrates:
In applications where the flowrate varies or where
shutoff valve opening and closure takes place in
batch operation, avoid rapid changes in flowrate
across the meter.
Operating the meter at flowrates in excess of
the maximum allowable flowrate will nullify the
guaranteed accuracy, reduce the meter life and
may result in faulty conditions, such as the seizure
of bearings or the rotor-to-measuring chamber
contact.
(2) Where the temperature of metered fluid changes:
Avoid rapid temperature changes in the meter.
Temperature changes of the fluid in the meter
should be held within 3°C per minute.
Extra care should be used particularly when making
a flow measurement in batch operation without
the provision of heat tracing of the piping where
the fluid temperature differs from atmospheric
temperature.
If rapid temperature changes are anticipated, heat
trace the piping assembly as well as the meter.
EXCESSIVE
FLOW
RAPID FLOW
VARIATION
RAPID TEMPERATURE CHANGES
Fig. 8.2
