10
2 -The balancing of the mechanical seal is indispensable when the pressure, measured on pump outlet, is about or
exceeds 10 bar.
3 -The balancing is suggested even for low duty pressure, when there are:
– pressure peaks due to first breakaway
– extremely viscous products
– frequent starting
– fragile or soft seal material (graphite, ceramic, PTFE).
4.5 - PACKING GLANDS Fig. 28 - 29
1 - Initial adjustement of the packing glands should be carried out during commissioning.
2 - After the pump has run for a few hours, the packing will have compacted and a further adjustment is necessary,
taking care to leave a slow drop to provide lubrication of the packing.
3 - When the dropping loss is too big and further tightening is no more possible replace packing rings as well as shaft
protection bush.
4.6 - LIP SEALS Fig. 27
1 -The lip seals are composed by a support, in which two lip gaskets type UM are arranged: one turned inside for
product sealing and the other turned outside for suction sealing. The shaft is protected by a bush in AISI 316.
2 -During the assembling, check the lip gaskets are rightly arranged on the support (244).
3 - Assemble the supports on rotor case, lubricate by means of grease between the gaskets and insert the bushes
(241).
4 -Being the gaskets already seated, assemble the rotor case and tighten the socket head screws of the bushes,
locking them on the shaft.
4.7 - CAUTIONS
1 - If the product is subjet to easy drying, crystallization or decantation, it's necessary to wash pump and piping system
at the end of each work or at the beginning of a long plant pause.
2 - The reversibility of the rotation direction, peculiarity of all OMAC pumps, allows the product return, emptying
discharge piping.
3 - If the pump hasn't run for long period, at starting check the sealing devices are not blocked, turning by hand the
pump shaft.
4 - If the product is subject to congelation or solidification, before starting, check the pumps and piping are not blocked
by solids, created during the pause.
4.8 - DAILY CHECK
1 - Visual check of all sealing devices and of general working.
2 - If a leakage from mechanical seal occurs, arrange a replacement as soon as possible in order to avoid the product
enters the bearing housing.
4.9 - WEEKLY CHECK
1 - Check the oil level of the pump and of the motor unit; if necessary top up by means of oil according to manufacturer
instructions.
2 - Check the rotor case and clean it, removing possible product deposits.
3 - Check that no siezures between rotors or among rotors and static surfaces of rotor case have occurred.
4 - Check the by-pass valve, when arranged, is not blocked after long working pause. To see it, it's necessary to
untighten completely the adjusting screw (59) and re-arrange it in its initial position, indicated by retainer (62)
Fig. 21.
4.10 - SIX MONTH CHECK
1 -If the pump works constantly at high temperature, over 120°C, check the lubricant oil health; if it has become dark,
arrange its replacement.
2 - Check the timing gears don't allow the rotors get in touch; otherwise replace the worn gears.
3 - Check the shaft stiffness; if they show a min. axial or radial play, replace the bearings.
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