Nova-Tech LMI Series G - SD Metering Pump - Manual (Page 23)

DO NOT APPLY PTFE TAPE TO THE
THREADS OF CHECK VALVE BODY THAT
SCREWS INTO THE HEAD (280), AS THIS
MAY PREVENT ADEQUATE SQUEEZE FROM
BEING APPLIED TO THE VALVE O-RING
WHICH COULD RESULT IN LEAKAGE.
1. Unscrew the valve body (424) from the pump head
(280).
2. Remove the cartridge valve assembly: cartridge in-
cludes ball (422), seat (420), ball guide (426), O-ring
(419), and washer (427).
3. Clean the valve body (424) and threaded port in the
head (280).
4. Press a new washer (427) into valve body (424).
5. Install new check valve assembly in orientation shown.
On discharge side, drop cartridge assembly (425) into
threaded port in head. The O-ring should be stretched
around outside of cartridge on same end as ball seat.
Screw valve body into discharge side of diaphragm head
until valve is hand tight. DO NOT OVERTIGHTEN.
On suction side, drop the cartridge assembly into check
valve body. The O-ring should be stretched around out-
side of cartridge on opposite end of ball seat. Screw
the suction valve body with cartridge valve into suction
side of head. DO NOT OVERTIGHTEN.
4.5.2 CHECK VALVE REPLACEMENT: LIQUID
ENDS D2 AND D4 - POLYMER (SEE FIGURE 9 OR
12)
NOTE THAT THE SEAT ORIENTATION IS DIF-
FERENT INSIDE THE SUCTION AND DIS-
CHARGE CHECK VALVES, BUT THE SEAT
MUST ALWAYS BE BELOW THE BALL WHEN
INSTALLED.
DO NOT APPLY PTFE TAPE TO THE
THREADS OF CHECK VALVE BODY THAT
SCREWS INTO THE HEAD (280), AS THIS
MAY PREVENT ADEQUATE SQUEEZE FROM
BEING APPLIED TO THE VALVE O-RING
WHICH COULD RESULT IN LEAKAGE.
Suction
1. Unscrew the valve body (424) from the pump head
(280).
2. Remove the valve assembly: assembly includes ball
(422), seat (420), Cartridge (426), O-ring (419), and
washer (427).
3. Clean the valve body (424) and threaded port in the
head (280).
4. Place a new washer (427) into valve body (424). Place
new seat (420) and new ball (422) inside new cartridge
(426) and place into valve body.
5. Add O-ring (419) and install new check valve assem-
bly in orientation shown.
On suction side, drop the cartridge assembly into check
valve body. The O-ring should be stretched around out-
side of cartridge on opposite end of ball seat. Screw
the suction valve body with cartridge valve into suction
side of head hand tight. DO NOT OVERTIGHTEN.
Discharge
1. Unscrew the valve body (424) from the pump head
(280).
2. Remove the valve assembly: assembly includes O-
ring (419), seat (420), ball (422), spring (428), cartridge
(426), and washer (427).
3. Clean the valve body (424) and threaded port in the
head (280).
4. Place a new washer (427) into valve body (424). Place
new spring (428), new ball (422), and new seat (420)
inside new cartridge (426) and place into valve body.
5. Add O-ring (419) and install new check valve assem-
bly in orientation shown.
On discharge side, drop cartridge assembly into threaded
port in head. The O-ring should be stretched around
outside of cartridge on same end as ball seat. Screw
valve body into discharge side of diaphragm head until
valve is hand tight. DO NOT OVERTIGHTEN.
4.5.3 CHECK VALVE REPLACEMENT: LIQUID END
SIZES D2 AND D4 - METALLIC (SEE FIG. 10 OR 11)
The metallic check valves used on liquid end sizes D2
and D4 (except slurry) are precision assembled at the
factory. Do not attempt to disassemble these cartridges.
If they become inoperative, flush them with solvent, wash
them with warm detergent and blow them out with com-
pressed air to remove any foreign matter. If this treat-
ment does not eliminate the trouble, the cartridge as-
sembly should be replaced.
17