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VACUUM FILL IN
THE FIELD
General:
It is very difficult
to fill a standard annular seal in the field. It is critical
that a very high vacuum be pulled and the fill fluid inserted
without any bubbles whatsoever; a bubble as small as a pea
will cause total failure. Seldom can a high enough vacuum
be developed with a handheld type of vacuum device; we strongly
recommend that filling be done under laboratory conditions,
such as at Branom, with a high quality two-stage vacuum pump
with a special rapid high vacuum and low rpm to allow high
vacuum without pump overheating.
Instructions:
- Attach tee
fitting "e" to fill port in Pressure Sensor housing.
- Attach gauge
or auxilary instrument to housing. Use TFE paste or tape
on threads, unless fill is silicon; use Rector seal if silicon).
Turn Sensor upside down.
- Close Ball
Valve "a".
- Fill funnel
"d" with sensing fluid. Be sure no air bubbles are in tubing
and sensing fluid.
- Open Ball Valve
"b" and stroke pump 'c" until gauge reads as high a vacuum
as possible (usually around 25" Hg Vacuum).
- Close Ball
Valve "b".
- Open Ball Valve
"a" very slowly. Funnel must be kept constantly full, without
agitation or bubble producing activity.
Do not allow any
air bubbles to enter pressure sensor.
- When pressure
Sensor is filled, close ball valve "a" and "b".
- Disconnect
tee fitting from Pressure Sensor. Relieve vacuum from vacuum
pump by pressing the release trigger (see illustration).
- Add additional
liquid to Pressure Sensor as required to fill to overflowing.
- Replace plug
in Pressure sensor housing.
- Open both ball
valves and drain tubing.
Caution: Do not
suck liquid through vacuum pump.
Place pressure
sensor and attached instruments under pressure for 48 hours
to test for leakage: especially important if any 316SS fittings
are used.
QUICK TEST VACUUM
PUMP:
The QUICK TEST
VACUUM PUMP is a portable, lightweight pump which will generate
approximately 23" Hg vacuum. It includes a 0.5% full scale
accuracy, 0-30" Hg test gauge which makes it a convenient
method to field calibrate vacuum instruments.
It is complete
with hose, bleed-off valve and pressure probe. Probe is identical
to that supplied with AIR and HYDRAULIC pumps and fits all
QUICK TEST fittings.
Better: Use a High
Vacuum Pump such as the 2-stage Welch Thomas #1405B-01 with
rapid high vacuum to 10 Torr @ 60 CFM (low RPM allows fast,
high pumping efficiency into low micron range)
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