Spring Loaded RTD Assembly with Screw Cover Head, 12in Long

Spring Loaded RTD Assembly with Screw Cover Head, 12in Long

Resistance Temperature Detectors (RTDs), also known as resistance thermometers, are precision sensors used to accurately measure process temperatures across a wide range of industrial applications. Their fundamental principle relies on the predictable change in electrical resistance of certain metallic elements as their temperature fluctuates. This characteristic allows RTDs to provide exceptional accuracy, repeatability, and interchangeability, making them a preferred choice for critical temperature sensing.

How RTDs Work: At its core, an RTD consists of a sensing element, typically made from pure metals like Platinum (the most common, especially Pt100 and Pt1000), Nickel, or Copper. When a small, constant excitation current is passed through this element, its electrical resistance changes proportionally with temperature. The resulting voltage drop, which is directly related to the resistance, is then measured and converted into a precise temperature reading.

Construction and Types: RTD sensing elements are generally manufactured in two primary forms:

• Wire-wound elements: A fine wire is precisely wound around a ceramic or glass core. These offer high stability and accuracy, often used in demanding applications.
• Thin-film elements: A thin film of resistive material is deposited onto a ceramic substrate. These are more compact, offer faster response times, and are generally more cost-effective. Both types are then hermetically sealed within a protective ceramic or glass capsule to ensure longevity and prevent contamination.

Accuracy and Lead Wire Compensation: Given that RTD elements typically have a low initial resistance (e.g., 100 ohms for a Pt100) and a relatively small change in resistance per degree of temperature change, the resistance of the connecting lead wires can introduce significant measurement errors, especially over long distances. To counteract this, RTDs commonly employ 3-wire or 4-wire configurations. These advanced wiring setups allow measuring instruments to effectively compensate for and eliminate the lead wire resistance from the overall measurement, ensuring the highest possible accuracy.

Operating Range and Applications: With the right choice of element material and robust protective sheathing, RTDs can operate reliably across an impressive temperature span, typically ranging from -200 °C to 600 °C (-328 °F to 1112 °F). They are widely used in pharmaceuticals, food and beverage, petrochemical, power generation, and HVAC industries due to their stability and precision.

Spring Loaded RTD Assembly with Screw Cover Head, 12in Long: This specific RTD assembly is designed for secure and reliable temperature measurement, particularly where contact pressure is desired to ensure optimal thermal transfer. The spring-loaded mechanism ensures constant contact between the sensor tip and the process, while the screw cover head provides a robust enclosure for the terminal connections.

Key Specifications for this Assembly:

• Temperature Range: -200 to 200°C
• Process Connection: 1/2" NPT-316SS (National Pipe Taper thread, made from 316 Stainless Steel for corrosion resistance)
• Conduit Opening: 3/4" NPT (for electrical wiring conduit connection)
• Insertion Length: 12 inches

Manufacturers often offer a wide range of RTD types, including single or dual-element configurations, various resistance values (e.g., PT100s, PT1000s), and specialized designs like Sanitary CIP (Clean-in-Place) configurations for hygienic applications. For unique requirements, custom-engineered RTD solutions, complete with connection heads, thermowells, and integrated transmitters, are also available to meet specific application needs.