ME990-3F
FORM #1132 ME990-3F IOM
Rev C 2/3/21
Operation
Since the ME990-3F internal valve is most often used on
transport trucks, the following procedure applies to that
type of application.
1.
Always open the internal valve before starting
the pump and before opening the valve on the
pump outlet.
2.
Normally leave the pumping system "wet" to
avoid repeated drying of the seals and to reduce
time in opening the internal valve. Drain the
piping only when codes or safe operating
practices require.
3.
If piping is dry or at lower pressure than the
tank, open the internal valve only about halfway
for a few seconds so that line pressure can
equalize before fully opening the operating
lever. The valve may not equalize if the
operating lever is moved to the fully open
position.
4.
Avoid flow surges which could close the built-in
excess flow valve. If the valve should "slug" shut,
stop the pump, close the nearest downstream
valve, and move the lever to mid-position to
speed equalizing until the valve opens. There will
be an audible click when the valve opens.
5.
Always leave the valve closed except when
transferring product.
6.
All valves should be completely open when
pumping. (Throttling type valves could prevent
the excess flow valve from closing when
required.)
7.
The operator must always be aware of where
the remote closure controls are located and
know how to operate the controls if any
emergency requires valve closure.
Troubleshooting
Internal Valve Will Not Open: This could be due to leakage
downstream, engaging the pump too soon or from
excessive wear in the internal valve. If excessive volume is
in the downstream system, a longer time is required to
equalize the pressures {tank and downstream} before the
pump can be engaged. To determine if the valve pilot seat
is opening, install a gauge downstream of the valve,
operate the valve actuator; if pressure does not build-up
to the tank pressure, the valve pilot seat is not open. This
test should be done with the pump off. If the pilot is not
opening, it may be plugged with dirt or some internal part
may be broken. If by operating the lever manually it can be
rotated past the fully open position, there is something
wrong internally and the valve must be disassembled.
Premature Valve Closure: This can be caused from
engaging the pump too soon, by an underrated excess
flow valve spring, or by an improperly connected internal
valve operating lever which does not fully open the valve.
The trouble could also be from a valve that has its inlet
port obstructed or from sudden line surges. In order to
check the valve opening travel, operate the lever manually
to the full travel, wait until valve opens (usually about 15
seconds), then engage the pump. If the excess flow closes,
the points mentioned above should be investigated.
Internal Valve Will Not Close: The stub shaft could be
binding or the stem could be bent in the valve. Before
disassembling the valve, check the actuator mechanism to
see that it operates freely by disconnecting it from the
valve lever and cycling it several times. Also, operate the
valve lever manually. If it sticks in the open position, the
packing and bushings should be replaced. This should free
the operating mechanism if the valve has not been
damaged internally. Refer to the "Maintenance" section.
FIGURE 4: Operational Schematic