Grundfos DMH 25X Installation And Operating Instructions Manual page 39

The paraffin oil between the diaphragms (Q) is con-
nected via the clamping sleeves (6q) to the contact
pressure gauge (S) in order to fill and activate the dia-
phragm leakage detection. The oil is able to pass be-
tween the diaphragms through the slits in the clamping
Caution
sleeves and the slits in the intermediate disk.
The clamping sleeves (6q) must therefore be installed
in such a way that the slits in the clamping sleeve face
the slits in the intermediate disk (3q). See fig. Dia-
phragm on dosing-head side.
10.7.3 Fitting the dosing head
• Fit the dosing head and cross-tighten the dosing head screws
using a torque wrench.
See section Start-up/shutdown for subsequent start-up!
Note
Related information
8.1 Initial start-up/subsequent start-up
10.7.4 Filling the double diaphragm with separating agent
After a diaphragm has broken, the ball non-return valve
must be cleaned before the diaphragm is filled with sepa-
Caution
rating agent. Only clean the ball non-return valve after a
diaphragm breakage!
Pump with double diaphragm: After the diaphragm has been
replaced, refill the separating agent between the diaphragms.
S
U
2u
T
1u
Dosing head with double diaphragm
Pos. Components
S Contact pressure gauge
T Ball non-return valve
U Connection piece
1u Filling screw
2u Deaeration screw
1. Set the stroke-length adjustment knob of the pump to 0 %.
2. Open the filling screw (1u) and deaeration screw (2u) by one
turn.
3. Connect the filling hose to the nipple of the filling screw (1u)
and, using the dosing syringe, inject the correct amount of
paraffin oil that is specified in the table below.
4. Close the filling screw (1u), but leave the deaeration screw (2u)
open.
5. Start the pump with a system counter-pressure and stroke-
length setting of 40 %.
6. Only close the deaeration screw (2u) when the separating agent
stops flowing (after 5 to 10 minutes).
After a few operating hours, especially if the pressure of
the pressure gauge is increasing, deaerate the double dia-
Note
phragm again.
Quantity of paraffin oil required for dosing pumps with a
double diaphragm (per dosing head)
Pump model
DMH 251-253
DMH 254
DMH 255
DMH 257
For product numbers of double-diaphragm filling compo-
Note
nents, see "Service kit catalogue" on www.grundfos.com
10.7.5 Filling with gear oil
Risk of leaking oil and damage caused by oil loss!
Caution
For each oil change, a new flat gasket (1b) must be fitted!
1. Check that the locking screw (B) is tightened.
2. Slacken and remove the oil-filling screw (F).
3. Set the stroke-length adjustment knob (L) to "0".
4. Slowly add the hydraulic oil through the oil-filling opening (F)
until the oil reaches the mark on the oil dipstick.
5. Wait 30 minutes.
6. Let the pump run for approx. 5 minutes with a stroke-length
setting of 0 %.
7. Let the pump run for approx. 10 minutes with a stroke-length
setting of 40 %.
10.7.6 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 model
DMH 251, 10 bar
DMH 251, 16 bar
DMH 251, 25 bar
DMH 252
DMH 253
DMH 254
DMH 255
DMH 257
Filling quantity
[ml]
4
6
8
10
Torque
[Nm]
8-10
10-12
13-15
8-10
10-12
50-54
50-54
50-54
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