Owner’s Manual for ONICON Insertion Turbine Flow Meters • September 27, 2001
13
First support the flow meter against the pipe pressure by holding
the electronics enclosure firmly in hand BEFORE loosening the
position clamping nut. The effort which will be required is the
same as that required for insertion of the meter and should be
calculated according to the formula in the prior section covering
insertion of the meter. This effort will be 0.11 times the pipe
pressure. If your footing is not secure, or if your ability to hold
the meter limited for any reason, DO NOT loosen the clamping
nut.
SLOWLY loosen the position clamping nut and carefully and
slowly allow the pressure to force the meter out of the pipe. This
is not at all difficult, but you must not let go of the meter until it
is fully withdrawn into the hot tap adapter. After the meter is
completely withdrawn, you may close the isolation ball valve.
The main cause of damage to meters comes from accidentally closing the valve on the turbine
assembly. To avoid this, gently rotate the meter by twisting the electronics enclosure back
and forth (twist the stem, do not bend it) while you slowly close the valve. If the valve
touches any part of the meter, you will feel it as you are twisting the meter. If the valve
touches anything, it means the meter is not fully withdrawn. Usually a gentle twisting motion
while withdrawing the meter will clear any obstruction and permit the meter to withdraw
completely. (Excessive build-up on the stem may require the hot tap ‘O’ ring to be lubricated
with silicone.)
After the valve is completely closed, you can safely unscrew the hot tap adapter from the
valve. Partially unscrew the adapter and allow pressure to vent from the hot tap adapter.
There will be very little water in the hot tap adapter; however, a small bucket or pan should
be held under the valve to catch any spilled water.
***CAUTION***
In hot water systems, even a small amount of water can cause serious personal
injury. Use extra caution when working with hot water meters.
3.5 ADJUSTMENT OF THE METER
***CAUTION***
If adjustment of the meter depth is required, the same procedure must be followed as
if the meter was being removed. Please carefully read the section above on removal
of the meter. Remember, the meter may be under high pressure and failure to follow
the procedure may result in serious injury.
Once the meter has been moved to its new depth, tighten the position clamping nut. Next,
place several turns of electrical tape around the stem just above the clamping nut so that at a
later time, when the meter is removed for service, it can be easily replaced at the same depth.
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