Nova-Tech LMI Series G - SD Metering Pump - Manual (Page 26)

Reassembly
THE ORDER OF ASSEMBLY AND ORIENTA-
TION OF THE SUCTION AND DISCHARGE
CHECK VALVES IS DIFFERENT. REFER TO
FIGURE 14 FOR PROPER ASSEMBLY OR-
DER 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 pump head, trapping a new O-ring between the
pump head and the check valve assembly.
DO NOT APPLY PTFE TAPE TO THREADS
OF CHECK VALVE BODY AS THIS MAY PRE-
VENT ADEQUATE SQUEEZE FROM BEING
APPLIED TO THE VALVE O-RING WHICH
WOULD RESULT IN LEAKAGE.
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 as-
sembly, trapping a new O-ring (419) between the cou-
pling and the check valve assembly.
4.6 DIAPHRAGM AND OIL SEAL BELLOWS RE-
PLACEMENT
BEFORE BEGINNING DIAPHRAGM RE-
PLACEMENT, MAKE SURE THAT ALL SHUT-
OFF VALVES ARE CLOSED AND ALL PRES-
SURE IS BLED FROM THE LIQUID END.
If failure of the oil seal bellows has occurred, it is rec
ommended that the diaphragm assembly and oil seal
bellows be replaced at the same time.
4.6.1 DIAPHRAGM REPLACEMENT: LIQUID END
SIZE SD2 (SEE FIGURES 6, 9, AND 10)
1. Loosen the head screws (Item 290 in Figure 9) and
remove the diaphragm head (Item 280 in Figure 9). Mark
the suction and discharge ports on the diaphragm head
prior to removal.
2. Remove the motor fan cover and turn the motor by
hand while adjusting the capacity control knob to 100%.
With the capacity set at 100%, turn the motor fan until
the diaphragm (Item 260 in Figure 9) is in the full for-
ward position (top dead center).
3. Hold the outer edge of the diaphragm and turn it coun-
terclockwise to unscrew it from the pump drive.
4. Discard and replace with new diaphragm. Make sure
that adaptor (Item 252 in Figure 9) is screwed in tightly
to connecting rod (Item 60. in Figure 7). Make sure that
seat ring (Item 230 in Figure 9) is in place. Apply a thin
layer of silicone grease to back (rubber side) of dia-
phragm before installation. Holding the edges of the
diaphragm, screw the diaphragm assembly onto the male
thread of the adaptor piece (Item 252 in Figure 9) until it
reaches its mechanical stop.
5. With the capacity still set at 100% turn the motor fan
until the new diaphragm is in the farthest rearward posi-
tion (bottom dead center).
6. Reattach the diaphragm head with the suction and
discharge ports in the correct positions. Tighten the
screws in a crosswise pattern to a torque of 45 in-lb.
7. While turning the motor fan, set the stroke adjust-
ment knob to the 0% position.
8. Reinstall motor fan cover.
4.6.2 DIAPHRAGM REPLACEMENT: LIQUID END
SIZE SD4, SD7, AND SD8 (SEE FIGURES 6, 11 - 14)
1. Mark the suction and discharge ports on the dia-
phragm head prior to removal. Loosen the head screws
(290) and remove the diaphragm head (280).
2. Remove the motor fan cover and turn the motor by
hand while adjusting the capacity control knob to 100%.
With the capacity set at 100%, turn the motor fan until
the diaphragm cap (240) is in the full forward position
(top dead center).
3. Hold the outer edge of the diaphragm (260) and turn it
counterclockwise to unscrew it from the pump drive.
4. While clamping on the hex on the diaphragm cap
(240), disassemble diaphragm assembly by removing
the hex nut (271) on the back of the diaphragm support
nut (270).
20