Dosing Of Combustible Media; Commissioning; Operation; Safety Instructions For Operating The Explosion-Proof - Grundfos DMH 28 Series Installation And Operating Instructions, Supplement

5.4 Dosing of combustible media

For dosing combustible media, see section 4.2.2 Permissible
dosing media.
5.4.1 Installation for feed mode

Warning

The pump must not run dry, even during
commissioning/recommissioning.
The pump should be installed so that the discharge line can be
deaerated during start-up of the pump to enable the dosing
medium to flow into the dosing head.
5.4.2 Draining off the dosing medium
Lines for draining off media safely should be connected to the
safety valves (such as the overflow valve in the discharge line on
the discharge side of the pump) or vent valves via which the
combustible media are drained off.
The media must be drained off safely in order not
Caution
to pose a risk to persons or property.
5.4.3 Protection against running dry / flow indicator
Warning
An explosive mixture of vapours may form in
tanks which are partially empty. The pumps must
not run dry in order to prevent explosive
atmospheres in storage tanks being transferred
to other areas.
The customer should install level indicators in
tanks or flow indicators on the discharge side of
the pumps to prevent them from running dry.
The intake of air must be prevented.
Caution
Check suction lines regularly to make sure they
are tight.
5.4.4 Diaphragm leakage detection
During operation, pumps must not become a
source for impermissible medium leaks (this is
Caution
particularly important where combustible media
are dosed).
The evaluation of the diaphragm leakage signal (electrically
isolated reed contact) of the diaphragm leakage detection must
be used to stop the pump immediately.
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6. Commissioning

For dosing combustible media, see section 4.2.2 Permissible
dosing media.
Warning
Risk of explosion due to overheating of the
pumps.
The pumps must not run against closed valves
and fittings.
Warning
The first time the pump is started up or when it is
restarted after the dosing head has been
emptied, explosive vapour mixtures may form.
The pump must run with a completely full dosing
head during start-up and when restarted:
• Fill the dosing head and suction line with the
dosing medium, or,
• with flooded suction, deaerate the discharge
line to enable the dosing medium to flow into
the dosing head.

7. Operation

7.1 Safety instructions for operating the
explosion-proof pump
Warning
Risk of explosion due to overheating of the
pumps.
The pumps must not run against closed valves
and fittings.
Warning
The pump must not run dry, even during
commissioning/recommissioning.
Faults, e.g. reduction in dosing performance,
may be caused by damage to the pump, leading
to an increased risk of explosion.
Caution
In the event of a fault during operation, the pump
must be stopped immediately and the fault
corrected.