Grundfos DMH 251 Installation And Operating Instructions Manual page 32

S
6q
2 Q1 5q
Fig. 40 Diaphragm on dosing-head side
Pos. Components
S Contact pressure gauge (installation position)
Q1 Diaphragm on dosing-head side
Q2 Diaphragm on oil side/pump side
3q Intermediate disk
4q Sealing rings
5q Covering rings
6q Clamping sleeves
The paraffin oil between the diaphragms (Q) is
connected via the clamping sleeves (6q) to the
contact pressure gauge (S) in order to fill and
activate the diaphragm leakage detection. The oil
is able to pass between the diaphragms through
the slits in the clamping sleeves and the slits in
Caution
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. 40.
13.7.3 Fitting the dosing head
• Fit the dosing head and cross-tighten the dosing head screws
using a torque wrench.
See section 11. Start-up / shutdown
Note
subsequent start-up!
13.7.4 Filling the double diaphragm with separating agent
After a diaphragm has broken, the ball non-return
valve must be cleaned before the diaphragm is
Caution
filled with separating 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.
32
3q
4q 3q 4q 5q Q2
for
1u
Fig. 41 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,
Note
deaerate the double diaphragm again.
Quantity of paraffin oil required for dosing pumps with
a double diaphragm (per dosing head)
Pump type
DMH 251-253
DMH 254
DMH 255
DMH 257
For ordering data for double-diaphragm filling components, see
service instructions.
S
U
2u
T
Filling quantity
[ml]
4
6
8
10