82.Duplex filter changeover procedure

Filters are mounted in pairs as a duplex system so that one can be used and other is kept on standby at a time. The filter can be utilized both in low pressure (suction) and discharge (high pressure) side of the system and is used to remove the smallest part of dirt which is carried away in the system. The cleaning frequency of filters depends on the type of the filter and is decided by the manufacturer. The schedule is generally included in the planned maintenance system on board.

When differential pressure is high filter should be cleaned.

The duplex system features continuous filtering capabilities. When it becomes necessary to clean or replace filter media during continuous operating conditions, follow the procedure outlined below:

1. Open balancing valve to fill clean vessel and equalize pressure in both housings.

2. Slowly move the mechanical actuator lever 90 to divert the flow to the clean filter vessel.

3. Close balancing valve.

4. Relieve the pressure from the filter vessel being serviced.

5. Drain housing sufficiently to access filter basket.

6. Remove cover by loosening closure assemblies sufficiently to allow them to swing free. Turn

 handwheel on top of housing to lift cover clear of basket retainer plate. Swing cover away

 from housing to gain access to strainer baskets and/or filter bags.

7. Remove filter basket and clean thoroughly, remove the filter bag (if applicable) and dispose of properly.

8. Remove debris and sludge from inside of bag/basket sealing surface and O-ring groove to

 avoid interference with cover seal or flow of fluid being filtered.
9.Install clean filter basket and filter bag (if applicable). Be sure filter bag is seated inside the basket retainer plate.
10.Inspect cover gasket for cuts or other signs of failure and make sure it is properly seated.
11.Swing cover back into position, and alternately tighten closure assemblies evenly to ensure a leak proof seal between cover and housing body. The recommended torque value for each Multi- basket Filter closure assemblies is 160-240 ft