
Thermistors

Thermistors exhibit a precise and predictable change in electrical resistance when exposed to a corresponding change in temperature. Positive temperature coefficient (PTC) thermistors exhibit an increase in electrical resistance when exposed to an increase in temperature and Negative temperature coefficient (NTC) thermistors exhibit a decrease in electrical resistance when exposed to an increase in temperature.
ACI Hazardous Thermistor Series features a ½ inch stainless steel probe with two, 22 AWG Etched Teflon colored lead wires to differentiate between the NTC sensor types. The sensors are manufactured using a double encapsulation process to eliminate moisture and the thermally conductive epoxy helps to increase response times. The heavy duty Feraloy Iron or Aluminum Connection Head comes standard. The sensors can be used in Duct, Wall Mounted and Immersion style configurations.
ACI Thermistor Duct Series is designed to be used in smaller duct applications and includes an insulation pad for sealing the duct and dampening vibration. The stainless steel probe features two, 22 AWG Etched Teflon colored lead wires to differentiate between the sensor types. The sensors are manufactured using a double encapsulation process to eliminate moisture and the thermally conductive epoxy helps to increase response times.
ACI Thermistor Flexible Averaging Series features an 18 AWG Plenum Rated cable sensing element with two, 12 inch 22 AWG Etched Teflon colored lead wires. The sensors are multipoint and provide a better overall average temperature on the air inside larger ducts when compared to a single point sensor.
Products
What is a Thermistor? Thermistors are thermally sensitive resistors that rely on the change in electrical resistance to measure temperature. As the temperature changes, the resistance changes. The resistance of a specific thermistor will equal a certain temperature based off of the scaling for that device. There are two different styles of thermistor that can be used. The Negative Temperature Coefficient (NTC) and the Positive Temperature Coefficient PTC). NTC thermistor’s resistance decreases with the increase in temperature. PTC thermistor’s resistance increases when the temperature increases.
What are the advantages and disadvantages of a thermistor compared to an RTD? Thermistors are less expensive than RTDs and are able to measure temperature changes faster due to their smaller size. They can provide more resolution or better accuracy within the range that they are rated to measure. However, the temperature range is more limited compared to RTDs. Anything higher than 350 degrees Celsius would all but eliminate a thermistor as a good option.