9090 Continuous Thermal Sensor
the alison control 9090 series continuous linear thermal sensor is a small-diameter coaxial wire which is capable of sensing temperature changes along its entire length. the sensor is constructed of a center conductor and an outer inconel 625 sheath. the center conductor is
electrically insulated from the outer sheath by a ceramic thermistor material.
since the thermistor has a negative coefficient of resistance, this means that the electrical resistance between the center wire and the outer sheath decreases exponentially as the surrounding (ambient) temperature increases.
when connected to the appropriate a888-mxxx control panel, the 9090 sensor can have multiple independent adjustable fixed temperature set points, become a rate of rise detector, identify the location of a hot spot, supply a constant temperature readout during a fire incident and be used as a temperature measuring device for process control.
the sensor has a diameter of approximately 0.085" (2.16mm and therefore has a small mass which permits it to sense changes in temperature rapidly. its response time index (rti) is 58. with proper selection of thermal sensor material, it can sense temperatures from 70º f (21º c) up to 1,200º f (649º c). it can withstand temperature extremes of from -60º f (-51.1º c) to 2,000º f (1,093º c).
the alison control 9090 series thermal sensor should not be confused with fixed-temperature open circuit devices which close only when a predetermined temperature or rate of temperature rise is reached. such open circuit devices-including fixed temperature, rate compensated or rate-of-rise thermostats; fire detecting wire containing a fusible salt; or a pair of twisted insulted steel wires- are not nearly as versatile or reliable.
the sensor is manufactured in lengths of 25 and 50 feet (7.6 and 15.24m). shorter lengths are available on special order. longer lengths, up to 1,000 feet (305m), may be assembled from a number of shorter lengths coupled together with hermetically sealed connectors. it is also possible to assemble several lengths having different temperature ranges so that hazards with different ambient temperature or heat conditions can be protected economically with a single length of sensor.
the 9090 sensor has been exposed to radiation levels as high as 200 megarads and has been certified by an outside testing laboratory to meet the requirements of ieee 323 and 344.