10 9.4.1 Dosing Liquid In The Pump Housing; Warning - Grundfos DME Serie Instrucciones De Instalación Y Funcionamiento

9.3.3 Reassembling the diaphragm and valves
Please observe as well section
Caution
5. Installation,
pump and 7. Start-up!
The pump must only be reassembled, if nothing
indicates that dosing liquid has entered the pump
housing. Otherwise proceed as described in section
9.4.1 Dosing liquid in the pump
This section refers to fig. 27.
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: 4.06 ft·lb (+ 0.37/- 0 ft·lb)
(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.
Cross-tighten the dosing head screws
with a torque wrench once before
Caution
commissioning and again after 2-5
operating hours at torque 4.06 ft·lb
(+0.37/-0 ft·lb) (5.5 Nm (+0.5/-0 Nm)).
7. Deaerate dosing pump (see section
venting of pump).
34
6.3 Priming/venting of
housing.
6.3 Priming/
9.4 Diaphragm breakage
If the diaphragm leaks or is broken, dosing liquid
escapes from the drain opening (fig. 27, pos. 9) on
the dosing head flange.
In case of diaphragm breakage, the safety
diaphragm (fig. 27, pos. 1) protects the pump
housing against ingress of dosing liquid.
When dosing crystallizing liquids the drain opening
can be blocked by crystallization. If the pump is not
taken out of operation immediately, a pressure can
build up between the diaphragm (fig. 27, pos. 3) and
the safety diaphragm in the flange (fig. 27, 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.

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
9.3.2 Dismantling the diaphragm and
valves.
To avoid any danger resulting from diaphragm
breakage, observe the following:
• Perform regular maintenance. See section
9.1 Regular maintenance.
• Never operate the pump with blocked or soiled
drain opening.
– If the drain opening is blocked or soiled,
proceed as described in section
9.3.2 Dismantling the diaphragm and
• Never attach a hose to the drain opening. If a
hose is attached to the drain opening, it is
impossible to recognize 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.
valves.