Nova-Tech LMI Series G - SG Metering Pump - Manual (Page 24)

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6. Screw coupling (445) onto check valve assem-
bly, trapping a new o-ring (419) between coupling
and check valve assembly.
4.4.1.5 Models SG5, SG6 & SG7 Liquid End -
Slurry Service Check Valves (Figure 14E &
14G):
Replacement
THE ORDER OF ASSEMBLY AND ORI-
ENTATION OF THE SUCTION AND DIS-
CHARGE CHECK VALVES IS
DIFFERENT. REFER TO FIGURE 14G
FOR PROPER ASSEMBLY ORDER AND
ORIENTATION. IF CHECK VALVE CAR-
TRIDGES ARE INSTALLED INCOR-
RECTLY, ONE OF THE FOLLOWING
WILL OCCUR: (A) IMMEDIATE SEVERE
DAMAGE TO PUMP MECHANISM, (B)
NO PUMPING, (C) REVERSE PUMPING
ACTION (FROM DISCHARGE LINE INTO
SUCTION LINE).
1. Unscrew valve body (424) from pump head
(280).
2. Remove the valve assembly (425): assembly
includes ball (421 or 422), seat (420), retain pin
(428, SG5 only), valve body (424), and two (SG5)
or three (SG6 & SG7 O-rings (419).
3. Remove and discard o-rings (419), seat (420)
and ball (421 or 422).
4. Clean valve body (424) and threaded port in
head (280).
5. Place a new O-ring (419) around seat (420).
Place new seat (420) and new ball (421 or 422)
inside valve body (424).
6. Add O-ring (419) and install new check valve
assembly in orientation shown.
NOTE: To assure a tight, leak free seal, new
o-rings should be used each time the check
valves are disassembled.
7. Screw correct end of check valve assembly into
liquid end (refer to Figure 14E or 14G), trapping a
new o-ring (419) between liquid end and check
valve assembly.
8. Screw coupling (445) onto check valve assem-
bly, trapping a new o-ring (419) between coupling
and check valve assembly.
4.4.1.6 Models SG5, SG6 & SG7 Liquid End -
Polymer Service Check Valves (Figure 14F):
Replacement
Suction
Follow the instruction for replacement of ball, seat,
& seal: liquid end SG6 and SG7 - plastic check
valves paragraph 4.4.1.1. The procedures are the
same.
Discharge
1. Unscrew valve body (425) from pump head
(280).
2. Remove valve assembly: assembly includes
two O-rings (419), seat (420), ball (422), poppet
(426), spring (423) and check valve body (425).
3. Replace O-rings (419), seat (420), ball (422),
poppet (426), and spring (423).
4. Clean valve body (425) and threaded port in
head (280).
5. Install new check valve assembly in orientation
shown.
On discharge side, drop cartridge assembly into
threaded port in head. Screw valve body into dis-
charge side of diaphragm head until valve is hand
tight.
DO NOT OVERTIGHTEN.
4.4.2 Diaphragm Replacement
BEFORE BEGINNING DIAPHRAGM
REPLACEMENT, MAKE SURE THAT
ALL SHUT-OFF VALVES ARE CLOSED
AND ALL PRESSURE IS BLED FROM
THE LIQUID END. MAKE SURE POWER
TO PUMP IS TURNED OFF AND CAN-
NOT BE ACTIVATED.