ASCO pressure and temperature radiation resistant construction switches are designed to be used outside the containment area of nuclear power plants to monitor pressure and temperature. Selection of the proper pressure/temperature switch for a specific application is of paramount importance. This
engineering information section describes principles of operation, types of switches, types of enclosures, and materials to assist in the proper selection.
Principles of Operation
The pressure/temperature switch will control electrical circuitsin response to changes in pressure or temperature. The pressure transducers are generally of the diaphragm piston type pressure sensor. The exceptions are in the higher pressure ranges, which use a piston with an o-ring seal. The piston defines the area that the pressure is applied to, converting the pressure to a mechanical force.
The temperature transducer is also a diaphragm piston type pressure sensor converting pressure to a mechanical force. The internal pressure is the vapor pressure of a chemical in a contained volume that is in direct relation to the temperature. The switch incorporates an adjustable spring force that opposes
the transducer piston force. When the transducer force is greater than the spring force, the piston rod mechanism moves to operate an electrical snap switch. When the transducer force is less than the spring force the piston rod mechanism moves to restore the electrical snap switch to the normal position.
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