Installation Operation and Maintenance Manual

Commissioning, Startup, Operation, and Shutdown (Continued)NOTICE:Make sure to lubricate the packing. Failure to do so may result in shortening the life of the packing and thepump.You must use an external sealing liquid under these conditions:• The pumped fluid includes abrasive particles.• The stuffing-box pressure is below atmospheric pressure when the pump is running with a suction liftor when the suction source is in a vacuum. Under these conditions, packing is not cooled andlubricated and air is drawn into pump.Conditions for application of an external liquidIf...The stuffing box pressure is above atmosphericpressure and the pumped fluid is clean.The stuffing box pressure is below atmosphericpressure or the pumped fluid is not clean.An outside source of clean compatible liquid isrequired.Then...Normal gland leaks of 40 to 60 drops per minute isusually sufficient to lubricate and cool the packing.You do not need sealing liquid.An outside source of clean compatible liquid isrequired.You must connect the piping to the lantern ringconnection with a 40 to 60 drops-per-minute leakrate. The pressure must be 15 psi (1.01 kg/cm 2 )above the stuffing box pressure.Pump primingPump priming with the suction supply below the pump (3796)Model 3796 is self-priming and does not require a foot valve in the suction line or manual priming prior tostartup (except for the initial charge). However, in a pressurized system, the pump requires an air vent or apermanent bypass line in the discharge piping to vent the evacuated air.This illustration is an example of priming a 3796 pump in a pressurized system.3796 Priming in aPressurized System71234651. By-pass line2. Concentric reducer3. Long radius elbow4. Shutoff valve5. Strainer6. Foot valve (if used)7. Discharge isolation valveFigure 16: Priming a 3796 pumpModel 3796 i-FRAME Installation, Operation, and Maintenance Manual 59