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

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three screws (441,442) and their split washers
(439). Since one screw (441) is shorter than the
others, be sure that it is screwed into the appropri-
ate hole.
4.4.1.3 Model SG5 Liquid End - Stainless Steel
Check Valve (Fig. 14B):
Disassembly
SG5 stainless steel check valves differ from the
plastic versions in that the ball seat is integral to
the ball guide. The seats cannot easily be
inspected for damage or wear. If you suspect that
the check valve may be damaged or worn, replace
the entire check valve assembly as per the instruc-
tions below.
1. Unscrew the coupling (445).
2. Unscrew the ball guide (424) from the liquid
end.
3. Remove and discard the o-rings (419).
4. Carefully clean any parts to be reused. If any
chemicals are used in the cleaning process,
ensure that they are compatible with the process
liquid.
Reassembly
THE ORDER OF ASSEMBLY AND ORI-
ENTATION OF THE SUCTION AND DIS-
CHARGE CHECK VALVES IS
DIFFERENT. REFER TO FIGURE 9 AND
14B FOR PROPER ASSEMBLY ORDER
AND ORIENTATION. IF CHECK VALVE
CARTRIDGES 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. Screw the correct end of the check valve
assembly into the liquid end (refer to Figure 14B),
trapping a new o-ring between the liquid end and
the check valve assembly.
NOTE: To assure a tight, leak free seal, new
o-rings should be used each time the check
valves are disassembled.
2. Screw the coupling (445) onto the check valve
assembly, trapping a new o-ring (419, 423)
between the coupling and the check valve assem-
bly.
4.4.1.4 Model SG5 Liquid End - Slurry Service
Check Valves, use until 1 June 2008 (Fig. 14E) :
Replacement
THE ORDER OF ASSEMBLY AND ORI-
ENTATION OF THE SUCTION AND DIS-
CHARGE CHECK VALVES IS
DIFFERENT. REFER TO FIGURE 8 AND
14E FOR PROPER ASSEMBLY ORDER
AND ORIENTATION. IF CHECK VALVE
CARTRIDGES 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 the coupling (445).
2. Unscrew the valve body (424) from the pump
head (280).
3. Remove and discard the valve assembly:
assembly includes two O-rings (419), slurry seal
ring (420), ball (422), check valve body (424), and
dowel pin.
4. Clean the new valve assembly and threaded
port in the head (280).
NOTE: To assure a tight, leak free seal, new
o-rings should be used each time the check
valves are disassembled.
5. Screw correct end of check valve assembly into
liquid end (refer to Figure 14E), trapping a new o-
ring (419) between liquid end and check valve
assembly.