Taylor-Wharton VJ Bulk Tank - Manual (Page 16)

VACUUM GAUGE TUBE
If the gauge tube is damaged or is suspected of giving inaccurate readings, replace it as follows:
1. Make certain that the gauge tube isolation valve is closed.
2. Unscrew the gauge tube from the valve. Use two wrenches, one on the tube, one on
the valve.
3. Clean the threads and opening of the valve.
NOTE: Do not use Teflon tape as a sealant on vacuum system fittings.
4. Thread the new gauge tube into the valve by engaging one thread. Apply Airserco
high vacuum sealant to remaining exposed threads. Tighten tube into valve, using two
wrenches. Do not over tighten.
5. Check vacuum following previously described procedure. The waiting period to
obtain a stable reading with a new gauge tube may exceed the specified 30 minutes.
This is due to out-gassing of the new gauge tube and the thread sealant.
6. After reading has been recorded, close gauge tube valve and disconnect Vacuum
Gauge. Install new vinyl cover over the gauge tube connector.
NOTE: If corrosion of the gauge tube is a problem, spray the tube housing with
"Krylon Crystal Clear Coating 1301" or equivalent acrylic spray. Do
not spray the contact pins of the electrical connector; this could cause
erroneous vacuum readings.
ANALYZING VACUUM DETERIORATION
If you decide to re-evacuate because of slow deterioration over a long period of time, go directly to
the Re-Evacuation procedure. If vacuum deterioration occurs over a relatively short period and
pressure is greater than 1,000 microns (1 mm Hg) absolute, suspect that a leak has developed in the
external casing of the tank. If deterioration is rapid and causes the bursting disk to rupture, suspect
leakage from the liquid container or internal piping.
NOTE:
An abnormally high vacuum reading without other evidence of vacuum loss (excessive
pressure, rapid venting, etc.) may be caused by a fault in the gauging equipment or by
improper operation of the equipment. Be sure that the vacuum gauge and the gauge
tube are in good condition and follow operating instructions carefully. Always be sure
that the gauge tube valve has been open for at least 30 minutes before taking a
reading.
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