box. Excess pressure from an external source can be very destructive to packing. More pressure is required, however, for abrasive slurries than for clear liquids. Examination of the leakage will indicate whether to increase or decrease external pressure. If slurry is present in the leakage, increase the pressure until only clear liquid drips from the box. If the drippage is corrosive or harmful to personnel, it should be collected and piped away.
A common error is to open the external piping valve wide and then control the drippage by tightening the packing gland. A combination of both adjustments is essential to arrive at the optimum condition. The life of packing and sleeve depends on careful control more than any other factor.
FLOWMETER
PRESSURE
GAUGEPRESSURE REDUCING VALVE
STUFFING BOX
FIGURE 9 – CONTROLLED PRESSURE
SYSTEM
15
