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Section 3
Rev. 06/15
Safety, Installation, Operations & Service Manual
DOPSM2080X012
3.6.5 Reassembly
The valve is reassembled in the reverse order of disassembly, observing the following pre-
cautions. Please reference Bill of Materials and Assembly Drawing for the correct location
of the replacement parts and correct torque specifications.
1. Inspect all parts and replace those worn or damage with TESCOM replacement parts.
2. All parts should be cleaned to the cleanliness level required for safe operation with the
media and system the valve will be used in. All parts in the flow stream must be free of
particles which could prevent proper seating on the valve stem.
3. Apply a thin uniform coating of fluorocarbon grease to the following parts: threaded
portion of the adjusting screw, the lower part of the threaded area of the stem retain-
er, all the o-rings.
NOTE: Do NOT apply any type of grease to the inlet and outlet connections.
4. Valve seat must be installed with the chamfered side towards the valve stem.
5. Thread the stem retainer into body hand-tight. Valve should be placed into a vise and
the stem retainer re-torqued to specifications. See Assembly Drawing.
After valve has been reassembled, it must be connected to a pressure source with a
media compatible with the use the valve and pressurized to check for internal and
external leakage and operation characteristics.
3.7 Valves - TESCOM VA, VG and VT Series
3.7.1 General
TESCOM VA, VG and VT Series valves are specifically engineered for application requiring
dependable controls. These valves are especially appropriate for installations where high
system pressures (up to 10,000 psig) are used.
3.7.2 Actuation types
The valve is closed or opened by applying low air pressure to the actuation port.
3.7.3 Operation
The normally closed (spring closed) VA and VG valves require a minimum pressure of 60 psi
applied to the actuation port to open. The normally open (spring open) VA and VG valves
require a minimum pressure of 60 psi applied to actuation port to close. The VT valve
requires a minimum pressure of 80 psi for actuation pressure.
TESCOM valves will operate with any liquid or gaseous media compatible with the wetted
materials. A filter is recommended for use in all but the cleanest media. Gaseous media
should be free of excessive moisture to prevent icing of the valve at high flow rates.
3.7.4 Maintenance
The following procedures are provided to enable the customer to perform all normal
maintenance and repair operations. These operations are more easily performed with the
valve removed from the line. However, in some cases repair may be accomplished without
removal of the valve body as long as the supply has been shut off and the inlet and outlet
pressures have been vented.
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