11
4 - Check the corrosion of the bearing housing; if necessary arrange its repainting by means of a paint, suitable to
protect it from a quick wear. The OMAC standard pumps are painted with: BRIGHT EPOXID ENAMEL RAL 7032.
If you carry out these checks sistematically, the pump will keep its initial performaces for many years.
5. - RELIEF VALVE AND MANUAL BY-PASS
5.1 - RELIEF VALVE
1 - Arranging a safety valve, directly on pump or plant, is always suggested to save the pump in case of wrong acts,
which may cause overpressure peaks.
2 - If the pump hasn't got a relief valve, it can not work with even partly blocked outlet pipe.
3 - Upon request OMAC pumps can be delivered with relief valve.
4 - The relief valve, directly arranged on pump end cover, is reversible and driven by a spring, register compressed.
5 - The relief valve adjustment must be carried on pump working because the recycle consistency depends on pump
speed, product absolute weight and viscosity.
6 - In order to avoid continuous vibrations, the relief valve must be adjusted in such a way that it starts working with
a pressure over 10% of duty pressure.
5.2 - RELIEF VALVE ADJUSTMENT Fig. 21
1 - Start the pump with the relief valve, still loose, i.e. with the spring not under pressure.
2 - Tighten the adjustment screw (59), compressing gradually the spring, checking the pressure on pump outlet doesn't
exceed the max. allowed pressure.
3 - Acting on adjustment screw and checking by means of a probe, find out the valve critical opening point, under the
required pressure.
4 - Compress the spring for 1/4 screw turn over the critical point in order to avoid vibrations.
5 - Put the register clamp (62) and tighten it by means of a suitable socket haed screw (65).
Fig. 11
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