What Tests are Made in Regulating Blow-down?
Since there are no simple test for routinely checking the amount of suspended solids in boiler-water, blow-down is usually controlled through use of a simple instrument which measures the electrical conductivity of the water. This test gives an estimate of the dissolved solids present in the boiler-water. Chloride tests are also used for blow-down control since chlorides are not reacted on by chemical treatment. By checking both the fee-water and boiler-water chlorides the number of feed-water concentra-tions can be calculated. In some higher pressure boilers, silica or iron tests may also be made to control blow-down.
