Humidistats are used in a number of devices including dehumidifiers, humidifiers and microwave ovens. In humidifiers and dehumidifiers the humidistat is used where constant relative humidity conditions need to be maintained such as a refrigerator, greenhouse or climate controlled warehouse.
Humidistats employ hygrometers but are not the same. A humidistat has the functionality of a switch and is not just a measuring instrument like a hygrometer is.
KP pressure controls are for use in refrigeration and air conditioning systems to give protection against excessively low suction pressure or excessively high discharge pressure. The controls are also used for starting and stopping refrigeration compressors and fans on air- cooled condensers.