RTD Element with Aluminum Head for Thermowell, 4in Long

Precision Temperature Measurement with Pyromation RTDs

This specific Pyromation RTD element is designed for use with a thermowell, featuring a 100 Ohm resistance, a 1/4 inch OD sheath that is 4 inches long, a 1/2 inch NPT SS hex fitting, and an aluminum head and block for robust protection and connection.

Understanding Resistance Temperature Detectors (RTDs): Resistance Temperature Detectors, also known as resistance thermometers, are highly accurate and reliable sensors used to measure process temperatures. Their operation is based on the principle that the electrical resistance of certain metallic elements changes predictably with temperature. Platinum is the most common and preferred material for RTD elements due to its linear resistance-temperature relationship, chemical stability, and wide temperature range.

How RTDs Work: An RTD sensor works by passing a small, constant excitation current through its element. As the temperature changes, the element's resistance varies, and this change in resistance is then measured as a voltage drop. This voltage is subsequently converted into a precise temperature reading based on established calibration curves (e.g., the Callendar-Van Dusen equation, commonly standardized by IEC 60751).

Construction and Types: RTD elements are typically manufactured in two main ways:

• Wire-wound elements: A small, fine platinum wire is coiled around a ceramic or glass core. These offer excellent accuracy and long-term stability, ideal for high-precision applications.
• Thin-film elements: A thin film of platinum is deposited onto a ceramic substrate. These are more compact, cost-effective, and offer faster response times, suitable for applications where space or budget is a concern. The sensing element is then sealed within a protective capsule, which is often housed within a durable metal sheath (like 316 stainless steel or Inconel) to withstand harsh industrial environments, corrosion, and high pressures.

Achieving High Accuracy: Wiring Configurations: Due to the low initial resistance of common RTDs (e.g., 100 Ohms at 0°C for a PT100), even small amounts of resistance in the connecting lead wires can introduce significant measurement errors. To counteract this, RTDs are often wired in 3-wire or 4-wire configurations:

• 2-wire: Simplest, but lead wire resistance is added directly to the sensor resistance, leading to potential inaccuracies.
• 3-wire: The most common industrial configuration, effectively compensates for lead wire resistance by measuring the resistance of two lead wires and subtracting it from the total.
• 4-wire: Offers the highest accuracy by fully compensating for lead wire resistance, typically used in laboratory and critical applications where precision is paramount.

Key Advantages of RTDs: RTDs offer several benefits that make them a preferred choice for many applications:

• High Accuracy: Excellent precision, especially platinum RTDs (PT100, PT1000).
• Stability: Maintain accuracy over long periods and repeated temperature cycling.
• Repeatability: Consistent readings under the same conditions.
• Wide Temperature Range: Capable of operating from approximately -200°C to 600°C (-328°F to 1112°F), depending on construction.
• Linearity: Exhibit a more linear output than thermocouples, simplifying signal conditioning.

Pyromation's Comprehensive RTD Solutions: Pyromation specializes in manufacturing high-quality RTDs and resistance thermometers for a vast array of industrial applications. We offer a comprehensive product line, from single- or dual-element RTDs and various resistance values (PT100s, PT1000s) to specialized Sanitary CIP configurations for hygienic processes. Whether you need a standard catalog item or a unique solution, our product engineers are adept at designing custom RTD measurement devices for your specific application requirements. This includes complete temperature sensor assemblies, incorporating connection heads, thermowells, and integrated transmitters to provide a complete, reliable sensing solution.

Specific Product Details: Description: RTD, 100 Ohm, 1/4" OD Sheath, 4" Long, 1/2" NPT SS Hex Fitting, Aluminum Head and Block