novaG
– 2K
Service Manual
19/23
Issue 1.6
Proportioning Pumps
WARNING!
Before resolving any kind of defect, make sure all of the pushbuttons are
off, that the general switch is in shutdown position and that the unit is disconnected from
the power supply source. Never handle the inside of the control panel with the unit
connected to the power supply. The metering pumps are components that work under
pressure; do not open any connection or perform repair or maintenance work on
components subject to pressure until all pressures have been completely released.
When pumps are functioning properly, it is not unusual for a small amount of resin to seep
through the pump packing onto the resin pump shaft. Periodically inspect shaft and wipe away
any residue when the proportiones is turned off.
Disassemble and clean the proportioning pumps annually, even if there are no apparent signs
of leakage. Make sure to replace all packings, o-rings and bushings during this maintenance,
even if there is no apparent damage. Not doing this can result in a premature failure of the new
components (please refer to tables 16 in the Service Manual NR-00025 for p/n of the different
models and sizes). Also inspect the lower and upper ball and the seat assembly, looking for
wear, hits or marks that may affect the normal functioning of the pump.
Check the condition of the ISO pump lubricant daily. Change the DOTP if it becomes gelatinous
or darker. Gel formation is due to moisture absorption by the pump lubricant. The interval
between changes depends on the environment in which the equipment is operating. The pump
lubrication system minimizes exposure to moisture, but some contamination is still possible.
Lubricant discoloration is due to continual seepage of small amounts of isocyanate past the
pump packings during operation. If the packings are operating properly, lubricant replacement
due to discoloration should not be necessary more often than every 3 or 4 weeks.
For those situations where the unit is operating under severe working loads or in special
working conditions, disassemble and clean the proportioning pumps every 6 months.
Inspect shafts, pistons and cylinder inner surface looking for scratches that could cause
premature leakage or damage to the seals.
Maintenance work may only be carried out by authorized professional, with the right knowledge.