Temperature Sensors: Types and Uses

Temperature sensors are indispensable tools in many commercial applications, including HVAC, refrigeration, manufacturing, and much more. They play a critical role in monitoring and controlling temperature, ensuring safety, efficiency, and optimal performance in a wide variety of different systems.

Among the different types of temperature sensing elements available, Belimo sensors typically use a thermistor or a Resistance Temperature Detector (RTD). Belimo offers both passive sensor assemblies, which output resistance (Ohms), and active sensor assemblies, which output voltage (Volts). In this article we’re going to review the different types of Belimo sensors, and some of the applications they’re used for.

Thermistors

Thermistors are temperature sensitive resistors that are made of ceramic or polymer materials. They show incremental changes in resistance relative to changes in temperature. In HVAC, Negative Temperature Coefficient (NTC) thermistors are used, meaning their resistance decreases with increasing temperature. Thermistors are highly-sensitive, inexpensive, and versatile, making them suitable for a wide variety of applications such as boilers or steam service where small temperature changes need to be detected accurately. The main limitation of the thermistor is that it can only measure accurately within a limited temperature range up to around 266℉. Belimo sensors can be configured with NTC10k (10k2), NTC10k Precon (10k3) or NTC (20k) signal type thermistors.

Resistance Temperature Detectors (RTDs)

The other type of sensing element that Belimo sensors use are Resistance Temperature Detectors (RTDs). Typically made of platinum or nickel, RTDs are known for their accuracy and stability over a wide temperature range of up to around 1200℉. Opposite NTC thermistors, with RTDs, as the temperature increases, the resistance increases. This response is called a Positive Temperature Coefficient (PTC.) Belimo offers platinum pt100 (100 Ohm) and pt1000 (1000 Ohm) RTDs, and Ni1000 (1000 Ohm) nickel RTDs. Between the two, Platinum RTDs offer the most stability over the largest temperature range.

When specifying a sensing element type, the primary distinction between thermistors and RTDs lies in their applicable temperature ranges. For temperatures exceeding 130°C, RTDs are the only viable option. At temperatures below this threshold, thermistors are typically favored for their precision and lower cost. Conversely, RTDs are the preferred choice in scenarios where accurate resistance at high temperatures is critical.

Belimo Sensors

Belimo sensors feature exceptional reliability, straightforward installation, and seamless integration with Building Automation Systems (BAS). Our sensor housings provide IP65/NEMA 4X protection, and offer quick installation and easy commissioning. Belimo offers temperature sensors for a wide variety of applications including for pipes, ducts, rooms, outdoor environments, and much more.

Belimo sensors offer innovative features such as selectable measurement ranges on active temperature sensors, strap-on sensors for retrofit jobs, and active temperature measurement compensation for room sensors.

In addition to temperature sensors, Belimo offers a full range of humidity, pressure, CO₂, volatile organic compound (VOC), and flow sensors. And like all Belimo products, Belimo sensors are supported by our world-class service and support team.

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