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~. <br />} scrubber Solution Level <br />The level of sodium hydroxide solution in the scrubber <br />reservoir is maintained by the addition of process water via <br />valve HV437. A level probe LIT440 mounted in a stilling well <br />opens and closes the valve, and also alarms high and low <br />j level conditions. An overflow prevents over-filling, and a <br />drain valve is provided to empty the reservoir for <br />maintenance. <br />NaOH Flow Rate <br />A locally-indicating flow meter (Rotameter FI606) in the <br />~~ Sodium Hydroxide Metering Pump discharge line shows NaOH <br />flow rate. The flow rate is set to the required value by <br />adjusting the stroke of the duty pump. <br />Scrubber Pressure Drop <br />A differential pressure gauge (PDI438) at the scrubber <br />indicates pressure drop across the packing. Abnormally high <br />pressure drop indicates that the packing is fouled. and <br />requires cleaning. Expected pressure drop is.3~.5" wc. <br />~-~ <br />Scrubber Solution Bleed <br />1 A locally-indicating flow meter (Rotameter FI443) in the <br />scrubber solution bleed line indicates bleed solution flow <br />rate. The bleed is adjusted to the required flow rate by <br />throttling a valve the in the bleed line. <br />scrubber Solution Circulation Rate <br />- A locally-indicating flow meter (Rotameter, FI439) is <br />located in the delivery line from the scrub_b_er recirculation <br />pump. The design circulation rate is gpm. <br />] 6.2 INTERLOCR9 <br />Interlocks between equipment drives ensure safe start-up and <br />1 shutdown in the correct sequence. Equipment in the pH <br />.i Adjustment System is interlocked as follows: <br />pH Adjustment Tank Agitator (04-AG-09) <br />Normal Start - no requirements <br />Normal Stop - no interlocks <br />Fault Trip - alarm only (tank continues to be <br />1 agitated by sparge air). <br />1 pj/1481rp 012591 6-2 <br />