Chiller
A chiller is a machine that removes heat from a liquid via a vapor-compression or absorption refrigeration cycle. This liquid can then be circulated through a heat exchanger to cool air or equipment as required. As a necessary byproduct, refrigeration creates waste heat that must be exhausted to ambient or, for greater efficiency, recovered for heating purposes. 

Ambient Air Temperature
The temperature of the room in which the Circulator, Chiller, etc., is located. Refrigerated equipment is generally required when the application temperature must be controlled near or below the ambient room temperature.

Ambient Temperature Range
This represents the highest and lowest ambient air temperatures at which the Circulator or Chiller was designed to operate.

Cooling Capacity
This is the amount of heat removal that a refrigerated device, such as a Chiller or Refrigerated Circulator, can provide at a given temperature. It is generally stated in watts, kcal/hour or BTUs/hour. It may also be expressed in tons.

Flow Rate
The volume of fluid pumped in a given amount of time. It is measured using water at a pressure of 0 psi (0.0 bar). Pressure Flow Rate is measured at the outlet port of the unit; Suction Flow Rate is measured at the inlet port.

Heat Exchanger
A device used to transfer heat from one material or medium to another. May also be called a condenser or evaporator when used within a system.

Open-Loop Circulation
This is generally used in reference to systems or applications where liquid is pumped from a Circulating Bath to an external open tank and then returned to the circulating bath. 

Operating Temperature Range
This is the temperature range that the equipment is capable of achieving and may be broader than the Working Temperature Range. This extended temperature range is particularly useful for the cooling of devices — such as lasers — that must be brought up to a temperature above ambient before operation can begin.

Refrigerant
A compound used in a refrigeration unit to extract heat from a process or internal reservoir. 

Water-Cooled Chiller
A type of chiller that transfers heat absorbed from the process fluid to another liquid, such as facility water from a cooling tower, as opposed to transferring the heat to the ambient air.

Working Temperature Range
This is the temperature range over which the equipment can achieve and control without auxiliary heating or cooling at the stated temperature stability specification.