Nova-Tech LMI Series G - SD Metering Pump - Manual (Page 27)

5. Make sure that stainless steel support nut (270) is
clean and free of corrosion. When cleaning the support
nut, take care not to scratch the smooth angled surface
of the support nut. If corrosion cannot be removed with-
out damaging the support nut, replace with a new one.
6. Install new diaphragm (260) onto diaphragm cap (240)
with the convolution in correct orientation. As shown in
Figure 6, the convolution in the Teflon diaphragm should
be facing down away from diaphragm cap (240) and
against (or pointing towards) the stainless steel sup-
port nut (270)
7. For Size SD4-stainless steel liquid ends, slide bolt
(250), washer (251), and O-ring (253) through the dia-
phragm cap and diaphragm as shown in Figure 6. For
all other liquid ends, install set screw (Item 250 in Fig-
ure 6) into diaphragm cap (240), with hex hole in screw
facing outward, until it is bottomed out (hand tight only)
in the diaphragm cap.
8. Slide support nut (270) onto set screw in correct ori-
entation shown in Figure 6.
9. Install hex nut onto back of support nut and tighten to
the following torque values dependent on liquid end size
and material. Torque diaphragm assembly as follows:
a) Liquid End Size SD7 and SD8 to 20 foot pounds.
b) Liquid End Size SD4-Plastic to 45 inch pounds.
c) Liquid End Size SD4-Stainless Steel tighten
until washer (Item 251 in Figure 6) is
contacting diaphragm cap (Item 240 in Figure
6).
10. Make sure that support ring (230) is in place and
then reinstall diaphragm assembly.
11. Apply thin layer of O-ring type grease to back of hex
nut (271) and reinstall thin PTFE washer (274) to back
of support nut.
12. Make sure that oil seal clamp ring (Item 210 in Fig-
ure 12) is in place. Screw diaphragm assembly into
connecting rod (Item 60 in Figure 7) until it reaches its
mechanical stop.
Note: Steps 11 and 12 are applicable to Liquid
End Size SD4 (See Figure 6).
13. Apply a thin layer of grease to the back of hex nut
(271).
14. Make sure that spring (Item 272 in Figure 13) is in
place and connecting rod is in full-forward position (at
100% capacity setting). Screw diaphragm assembly
into connecting rod cross piece (Item 61 in Figure 13)
until it reaches its mechanical stop.
Note: Steps 13 and 14 are applicable to Liquid
End Size SD7 and SD8 (See Figure 6).
15. With the capacity still set at 100% turn the motor
fan until the diaphragm is pulled back to the rearward
position (bottom dead center).
16. Reattach the diaphragm head with the suction and
discharge ports in the correct positions. Torque the
head assembly screws in a crosswise pattern as fol-
lows:
a) Liquid End Size SD2 and SD4 to 45 inch pounds.
b) Liquid End Size SD7 and SD8 to 90 inch pounds.
17. While turning the motor fan, set the stroke adjust-
ment knob to the 0% position.
18. Reinstall motor fan cover.
4.7 OIL SEAL BELLOWS REPLACEMENT (ITEM 70
IN FIGURE 7)
BEFORE BEGINNING OIL SEAL REPLACE-
MENT, MAKE SURE ALL SHUT-OFF VALVES
ARE CLOSED AND ALL PRESSURE HAS
BEEN BLED FROM THE LIQUID END (PUMP
HEAD). WHEN REPLACING THE OIL SEAL,
THE DIAPHRAGM ASSEMBLY MUST BE RE-
MOVED FIRST. FOR EASE OF SERVICE, IT
IS RECOMMENDED THAT THE OIL SEAL BE
REPLACED IN CONJUNCTION WITH THE DIA-
PHRAGM ASSEMBLY.
1. Disconnect connections to the pump motor terminal
box. Be sure to note the wiring layout before discon-
necting from box.
2. Set the stroke adjusting knob to 100%.
3. Disconnect the suction and discharge connections
to the pump head check valves.
4. Mark the suction and discharge ports on the dia-
phragm head prior to removal. Loosen the head screws
(Item 290 in Figure 12) and remove the diaphragm head
(Item 280 in Figure 12).
5. 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 assembly (Figure 6) is in the full forward
position (top dead center).
6. Hold the outer edge of the diaphragm assembly (Item
260 in Figure 6) and turn it counterclockwise to unscrew
it from the pump drive.
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