A high brine density indicates that too much of the feedwater is being converted into distillate. Operation with a high brine density causes excessive scale on heat transfer surfaces. This causes poor quality distillate due to excessive vapor formation. There is possible carryover and reduced efficiency due to the loss of heat energy carried over with the brine. The density should never exceed this level.
Brine density is measured with a salinometer, which works on the same principle as a hydrometer.
The float, or hydrometer, is a hollow metal shell attached to a square stem, weighted with shot at one end. A brine sample is drained into the pot from a test valve and the temperature is measured. The temperature must be adjusted to correspond with one of the temperature scales on the salinometer to accurately measure the density. The salinometer is then placed in the pot, weighted end down, and allowed to float in the brine. The brine density is read where the brine water level crosses the scale on the side of the graduated stem that corresponds to the brine temperature.