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8.3.3 Reassembling the diaphragm and valves
The pump must only be reassembled, if nothing
indicates that dosing liquid has entered the pump
housing. Otherwise proceed as described in section
8.4.1 Dosing liquid in the pump housing
This section refers to fig.
1. Screw on new diaphragm (3) clockwise.
2. Attach the dosing head (5).
3. Install screws (7), in case of PP or PVDF dosing
head together with the front plate (8), and cross-
tighten with a torque wrench.
– Torque: 5.5 Nm (+ 0.5/- 0 Nm).
4. Install new valves (4, 6).
– Observe the flow direction (indicated by an
arrow on the valve)!
5. Install the deaeration valve.
6. Connect suction, pressure and deaeration hoses.
7. Deaerate dosing pump (see section
8.4 Diaphragm breakage
If the diaphragm leaks or is broken, dosing liquid
escapes from the drain opening (fig.
, pos. 9) on
the dosing head flange.
In case of diaphragm breakage, the safety
diaphragm (fig.
, pos. 1) protects the pump
housing against ingress of dosing liquid.
When dosing crystallising liquids the drain opening
can be blocked by crystallisation. If the pump is not
taken out of operation immediately, a pressure can
build up between the diaphragm (fig.
, pos. 3) and
the safety diaphragm in the flange (fig.
, pos. 1).
The pressure can press dosing liquid through the
safety diaphragm into the pump housing.
Most dosing liquids don’t cause any danger when
entering the pump housing. However a view liquids
can cause a chemical reaction with inner parts of the
pump. In the worst case, this reaction can produce
explosive gases in the pump housing.
To avoid any danger resulting from diaphragm
breakage, observe the following:
•
Perform regular maintenance. See section
.
•
Never operate the pump with blocked or soiled
drain opening.
– If the drain opening is blocked or soiled,
proceed as described in section
8.3.2 Dismantling the diaphragm and valves
•
Never attach a hose to the drain opening. If a
hose is attached to the drain opening, it is
impossible to recognise escaping dosing liquid.
•
Take suitable precautions to prevent harm to
health and damage to property from escaping
dosing liquid.
•
Never operate the pump with damaged or loose
dosing head screws.
Caution
Please observe as well section
and
!
Caution
Cross-tighten the dosing head screws with
a torque wrench once before
commissioning and again after 2-5
operating hours at 5.5 Nm (+ 0.5/- 0 Nm).
Warning
Danger of explosion, if dosing liquid has
entered the pump housing!
Operation with damaged diaphragm can
lead to dosing liquid entering the pump
housing.
In case of diaphragm breakage,
immediately separate the pump from the
power supply!
Make sure the pump cannot be put back
into operation by accident!
Dismantle the dosing head without
connecting the pump to the power supply
and make sure no dosing liquid has
entered the pump housing. Proceed as
described in section
