Working Electrical Salinometer
The electrical supply to the salinometer must be DC. The potentiometer is provided to give a fixed standard calibration voltage so that no errors to voltage differences exist.
Pure water is non-conducting so that current flow is an indication of impurities, i.e. the greater the current the greater the impurity in the water.
When the impurity content exceeds a fixed value the current is sufficient to operate the relay 2 so giving visual or audible warning by closing the circuit. Continued operation at increased current would cause Relay 1 to short circuit the meter and so protect it.
Water temperature increases conductivity so that temperature compensation is required. A temperature compensating thermometer is a shunt across the meter. Temperature increase causes a rise of mercury level and a cutting out of resistance which allows more current through the shunt and less through the meter. The correct calibration current through the meter is fixed; current variations due to temperature are shunted.
"Steam Engineering Knowledge for Engineers" by Thomas D. Morton
More by this Author
It sometimes necessary to obtain an approximation to the power of the ship without restoring to model experiments, and several methods are available. One system which has been in use for several years is the admiralty...
Shell and Tube, Plate Heat Exchangers Advantages Simple and Compact in size Heat transfer efficiency is more Can be easily cleaned No extra space is required for dismantling Capacity can be increased by...
Linear resistors are those in which current produced is directly proportional to the applied voltage. Their current versus applied voltage is straight and linear. In other words, their resistance remains constant. ...