Wachs RS-2, Руководство пользователя

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RS-2
7
Valve Maintenance Procedure
A valve that has not been operated for a number of
years needs to be closed by using a series of up
and down motions. Occasionally, crews attempting
to close a difficult valve use a T-handle or a cheater
bar, applying a great deal of pressure in one direc-
tion simply to force the valve closed. The correct
way to exercise a valve is to begin with a steady
amount of torque in the direction necessary to close
the valve, moving through five to ten rotations, then
the direction should be reversed for two or three
revolutions, followed by five or ten more turns in the
closing direction. This procedure should be re-
peated until full closure is attained.
The reason for the cautious approach is that
tuberculation and sediment have probably built up
on the gates, stem, and slides. By using the proce-
dure described, water in the system can flush the
debris that has broken away from the gate slide.
The stem is exercised through the series of
up and down motions. Once the valve has been fully
closed, it should be opened a few turns so that the
higher velocity water flowing under the gates can
move the remainder of the sediment downstream.
After the valve is reopened, it should be turned in
the closing direction one or two revolutions. Thus,
the next time the valve is operated, it will not be
SECTION III
SET-UP AND OPERATION
necessary to start with a nut and stem
jammed against the bonnet, and there will be
no guesswork about which way to turn
the nut because the valve will be free. Also, if
it is inadvertently turned the wrong way, one
or two turns can be made before a positive
stops occurs, and by reversing direction, full
operation of the valve can be effected.
Using the RS-2 machines to operate valves
is easier on the valve because a steady
turning torque is applied rather than jerky
motions. This prevents the stem breakage
that is sometimes caused by turning the
valve by hand. Also, more valves can be
turned in less time. A further advantage is that
information about each valve can be gener-
ated automatically by the revolution counter
and torque gauges for inclusion on perma-
nent records.
HOW TO DETERMINE AN
UNKNOWN VALVE ROTATION:
When the direction to turn the valve
stem is not known, select a rotation
direction and proceed with caution. If
resistance is felt, immediately reverse
the rotation. Continue this procedure,
reversing direction when resistance is
felt, until a free turning direction is
achieved. Document the direction,
open or closed position, and number
of turns required.