Replacing The Diaphragm For Dosing Head With Double - Grundfos DMH 28 Serie Montage- Und Betriebsanleitung

10.6.6 Checking the oil level
1. Switch off the pump, check the oil level and add oil, if
necessary.
2. Refit the oil-filling screw (F).
After initial start-up and after each time the
diaphragm is changed, tighten the dosing head
screws.
Caution
After approximately 6-10 operating hours or two
days, cross-tighten the dosing head screws using a
torque wrench.
Torques
Pump type
DMH 280
DMH 281
DMH 283
DMH 285
DMH 286
DMH 287
DMH 288
10.7 Replacing the diaphragm for dosing head with
double diaphragm
Warning
Wear protective clothing (gloves and goggles) when
working on the dosing head, connections or lines!
The dosing diaphragm should be replaced with each
gear oil change.
Before removing the dosing head, valves and lines,
empty any remaining medium in the dosing head into
a drip tray by carefully unscrewing the suction valve.
Only use original Grundfos gear oil!
For product numbers, see "Service kit catalogue" on
Note
www.grundfos.com
10.7.1 Removing the dosing head
1. Close the suction and discharge lines and loosen the suction
and discharge valve connections.
2. Loosen the six dosing head screws (1q with 2q).
3. Remove the dosing head (2).
10.7.2 Replacing a double diaphragm
1. Clean the intermediate disk (3q), sealing rings (4q) and
covering rings (5q). After a diaphragm breakage, replace the
parts by new ones.
2. Remove both clamping sleeves (6q) slightly using pliers. After
a diaphragm breakage, replace the parts by new ones.
3. Measure the outer wall thickness of both new diaphragms (Q1
and Q2): s1 < s2 .
(Q1) (Q2)
34
Torque
[Nm]
55-60
17-19
Fig. 42 Installation of diaphragm
27-30
1) The shape of the diaphragm varies depending on pump type.
50-54
80-85
Pos.
50-54
1q
75-80
2q
2
Q1/Q2
3q - 5q
Caution
4. Fit both new diaphragms (Q1 and Q2) and the parts (3q - 5q)
in the correct order, as is shown in the diagrams (the clamping
sleeves (6q) are used for centring purposes).
Fig. 43 Diaphragm on dosing-head side
Pos.
S
Q1
Q2
3q
4q
5q
6q
s < s
1 2
2q
1q
2
Q1 3q - 5q Q2
1)
Components
Dosing head screw
Intermediate disk
Dosing head
See fig. 43
Observe correct installation of diaphragms (Q1 and
Q2)! See fig. 43.
Fit the thinner diaphragm (Q1) on the dosing side
and the thicker diaphragm (Q2) on the oil side/pump
side!
S
6q
3q
2 Q1 5q 4q 3q 4q 5q
Components
Contact pressure gauge (installation position)
Diaphragm on dosing-head side
Diaphragm on oil side/pump side
Intermediate disk
Sealing rings
Covering rings
Clamping sleeves
Q2