15 - MAINTENANCE OF DOSING PUMP HEADS
15.1- Maintenance of piston pump heads A
15.1.1 - Piston seal check and replacement
The check and maintenance operations program depends on the conditions of use. Should any failures
occur with product leakage from the hole under the lantern due to the wear of the gaskets, it must be
promptly replaced.
Before operating on the pump, the maintenance personnel
must make sure that the pump is stopped and disconnected
from the electrical power supply and that the system is
depressurised and empty.
The operations that must be carried out for disassembly of
the pump head and of the piston are the following:
❖ Pump head disassembly
• Remove the lantern cover.
• Remove the pump head from the lantern.
• Remove damaged gaskets from the pump head.
❖ Disassembly for piston replacement
• Loosen the counter-locking nut ref. 2/6
• Fully unscrew the locking nut ref. 2/5 from the slide joint
ref. 41
• Fully unscrew the piston from the piston rod ref. 2/2
• Check piston wear, if there are scratches or scoring replacement is recommended.
After having completed maintenance and connected the pump to the system, screw the ring nut
2/5 leaving a slight clearance without tightening, turn the pump for a few seconds so that the
piston finds the correct centring in the pump head, then finally tighten the ring nut ref. 2/5 and
counter-ring nut ref. 2/6.
15.1.2 - Pump head with gasket washing
This type of pump head is used when the product can
SEDIMENT or CRYSTALLISE.
Continuous washing of the area where the gaskets are
housed with water, promotes the detachment of any
incrustations, prevents the product from solidifying and
producing abrasion on the piston and damaging the profiles
of the seal gaskets.
Gasket washing:
By using the needle valve "C", adjust the flushing with a flow
rate of 40-50 l/h for at least 10-15 minutes after the pump is
stopped and continuously during dosing. Dirty flushing water
must be conveyed for disposal.
Pump head and valve washing:
Once dosing is terminated, before stopping the pump, close
valve "A" and simultaneously open valve "B", allow the water
for washing to circulate for about 3/4 minutes.
Once this amount of time has passed, stop the pump and
allow the water for washing to flow until it is clear.
Once washing is complete, close valve "B", open valve "A".
The pump is ready for dosing.
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