Pump-discharge-flush system

In order to aid in the removal of the contaminants from vacuum surfaces, a pump, discharge, flush, pump sequence can be used. In this operation, the system is pumped down to a low pressure, the conductance is decreased, and the pressure is raised so that a discharge can be established. The gas discharge desorbs the contaminants and when the pumping system is opened to full conductance the contaminants are pumped out of the system. 

Lube oil system from pump discharge to the distribution system should be flushed with lube oil at 160 F-180°F. Oil should flow across a 200 mesh screen and flushing should cease when no more dirt or grit is found on the screen. 

If the chlorate reactor is a vessel, a level control loop is necessary. The transmitter should be of the flush-diaphragm type with wetted parts of tantalum. The control valve, located in the pump discharge piping, should be fully lined with PTFE. The size of the system will determine the type of valve to be used. 

The permeate itself is often the ideal back-wash fluid since it has been through the membrane once. Unfortunately, permeate by itself will not always restore the flux (see Figure 3.71) and more aggressive cleaning solutions must be used. An auxiliary pump and filter must be provided to deliver the cleaning solution under pressure through the permeate port to the shell side of the module. The materials back-flushed will exit from the fiber lumen and must be discharged from the system so as not to redeposit on the walls of the fiber. 

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