KINNEY KTC SERIES, Installation, Operation And Maintanance Manual

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To read blank off pressure, close the pump inlet by means of a vacuum valve or blank off plate.
Connect a vacuum gauge to the suction side and position the gauge tube, facing downward into the higher area of
the manifolding so that the tube will not become flooded and blocked by splashing pump oil. If the pump is dis-
connected from the process equipment, connect a 90-degree elbow, extending upward, to the inlet flange and bolt
the blank off plate, with gauge connection, the open elbow flange.
Operate the pump for a minimum of 15 minutes and record the lowest pressure reached. Average blank off read-
ing is.0001 to .0005 microns with a McLeod gauge, and 1 to 10 microns with a thermocouple gauge. The specifi-
cation pressure is 0.2 microns, McLeod gauge reading. If the McLeod gauge reading is low and the thermocouple
gauge reading high, the pump oil is contaminated, (see “Oil Contamination”). A high reading of both the McLeod
and thermocouple gauges indicates that an air leak is present..
Checking Process Equipment
Attach a vacuum gauge (See INSTALLATION, Vacuum Gauges) to connection on the system side of the isolation
valve. For this test, the system should be clear of any process work, which might give off vapors and change the
reading. Run the pump to obtain the best vacuum possible with the valve open, then close the valve and observe
the pressure rise. If the pressure rise is greater than desired, the leaks should be eliminated. Check the system
carefully for loose joints and obvious leaks. Use a leak detector if available. The trouble can be isolated further by
applying the following procedures:
A. Isolate each segment by valves or blank off plate at convenient location. Pump down each segment of the pro-
cess equipment individually, starting at the segment closest to the vacuum pump.
B. Check the lowest pressure attainable when each segment is added. If the pressure is close to that obtained
previously, add the next segment. If the pressure is not close to the previous reading, leak test the last seg-
ment.
C. When leak checking process chambers, start at the air and gas inlet valves, doors, sight ports, electrical and
mechanical feedthroughs, gauge tube fittings, and any other gasketed penetrations and O-Ring connections.
After a suspected leak has been found, cover it with plastic sealing compound, such as Apiezon Q, and check
the equipment performance before sealing the leak permanently. Thus, all permanent repairs can be made at
the same time.
If a leak detector is not available, use the following methods to locate leaks:
1) Cover suspected leaks with a low vapor pressure sealing compound (such as Apiezon-Q, James Biddle Com-
pany or Shell Company; or Duxseal, Mansville Corp). Do this while pumping on the equipment and monitoring
the pressure. A sudden decrease in pressure indicates that a leak has been covered. Repair leaks perma-
nently as necessary.
2) If the leak is large, causing pressures over 1 Torr, (1 mbar), pressurize the process equipment with one psig
(70 mbar) of clean compressed air and paint a soap solution on suspected leak areas and bubbles will indicate
leaks.
If the leak is small causing pressures less that 1 Torr (1 mbar), use a fast acting medium such as acetone, alcohol,
freon or helium. Position the vacuum gauge head downstream from the suspected leak area, between the leak
and pump. When the pressure has been reduced so that the gauge may be used, apply the probing medium to
suspected leak areas using a squirt gun or brush. If the probing fluid is directed at the leak or an area
1) close to it, a sudden change in pressure will occur. Cover suspected leak with plastic sealing compound and
continue leak checking until desired pressure is obtained.
2) If leak checking fails, disassemble and remake all demountable joints and connections using new gaskets or
vacuum sealing compound such as Kinseal. Temporary gaskets may be fabricated from sealing compound
but these should not be made too thick since the material may be squeezed into the equipment.
Discharge Valves
If the cause of poor pump vacuum is not due to leaks or oil contamination, the next step is to inspect the discharge
valves. The discharge valves are located at the exhaust port of the backing stage chamber. They should not cause
trouble unless they are mechanically damaged or are prevented from sealing properly due to foreign matter on the
valve seat. Under normal pump usage, the valves should be replaced annually. When the pump is operating at
blank off without gas ballast, a sharp hydraulic noise (click) indicates proper valve operation.
The poppet type valve has six flat, washer-like springs, which press against a sealing disk. The disk fits against a
seal forming a tight seal. The springs are maintained in place by a lift stop and the entire a valve is held together
by a capscrews. The valves are attached to the cylinder by means of screws and a hold-down plate.
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