dmf2dl5sm-rev0317
Model DMF2 Page 8
DIAPHRAGM SERVICING
Diaphragms can be inspected or the diaphragm assembly removed
without removing the suction and discharge flanges. Remove (8) nuts
around the chamber flange, and the housing assembly will pull off. Flap
valves can be inspected for proper seating at this point as well as the
diaphragm. Use care to keep foreign matter from behind the diaphragm.
The opposite diaphragm may be inspected by the same procedure.
If either diaphragm has to be replaced, follow closely these steps:
Pull the outer diameter of one diaphragm off the (8) capscrews. NOTE: One
side only! On the free diaphragm assembly, use a 3/8" allen wrench to turn the
assembly (diaphragm, plates and screw) loose from the shaft. Once the assembly
has turned, it will turn out by hand by use of the diaphragm. Now the opposite
diaphragm assembly and the drive shaft will pull free from the capscrews and pump
intermediate assembly. The interior components consisting of sleeve bearings,
rod seals, and pilot valve actuator bushings are now accessible for service if
required. Hold the shaft in a clamping device making sure to protect surface
of shaft so as not to scratch or mar it in any way. The diaphragm assembly
will turn loose. To disassemble the components, turn a 1/4"-20 capscrew by
hand into the tapped hole in the inner plate. This keeps the plate from turning
while the socket head capscrew is removed. To do this, place assembly in a
vise so the two protruding ends of screws are loose in the vise jaws (about
3/4" apart). Turn the center screw loose from the back plate and the assembly
will come apart.
REASSEMBLY
All procedures for reassembling the pump are the reverse of the previous
instructions with further instructions as shown:
1.The diaphragm assemblies are to be installed with the natural bulge
outward or toward the head of the center screw. Make sure both plates are
installed with outer radii against the diaphragm. After all components are in
position in a vise and hand tight, set a torque wrench for 480 inch pounds
(40 ft. pounds) (54.23 Newton meters) using a (3/8") allen head socket. After
each diaphragm sub assembly has been completed, thread one assembly
into the shaft (held near the middle in a vise having soft jaws to protect the
finish) making sure the stainless steel washer is in place on the capscrew.
Make sure 1/4"-20 mounting screw has been removed and that the bumper
(Item #19 on drawing) is in place in the shaft.
Install this sub assembly into the pump and secure by placing the outer
chamber housing and capscrews on the end with the diaphragm. This will
hold the assembly in place while the opposite side is installed. Make sure
the last diaphragm assembly is torqued to 30 ft. lbs. (40.67 Newton meters)
before placing the outer diaphragm over the capscrews. If the holes in the
diaphragm flange do not line up with the holes in the chamber flange, turn
the diaphragm assembly in the direction of tightening to align the holes so
that the capscrews can be inserted. This final torquing of the last diaphragm
assembly will lock the two diaphragm assemblies together.
Place remaining outer chamber on the open end and tighten down the
securing nuts gradually and evenly on both sides.
Caution should be used while reassembling flap valves. The valves are
designed for some preload over the retainer hinge pad. This is done to insure
proper face contact with the seat. After all parts are in place, tighten the lock
nuts down on the assembly to the point where visual inspection shows that
seat and valve face mate without gap. This is important for dry prime. However,
after priming action has started, valves will function due to differential pressure
without concern or trouble.
