PR-18

Supported Applications

The Omega PR-18 series consists of industrial RTD probes featuring an aluminum protection head with a flip-top design. These sensors incorporate PT100 Ω or PT1000 platinum RTD elements and are designed for direct insertion into thermowells, tanks, vessels, and large pipes to measure flow material temperatures.

Operating Conditions & Performance

The series offers three distinct process temperature ranges depending on the model configuration: PR-18L (Low) covers -50 to 250°C (-58 to 482°F); PR-18H (High) spans -50 to 450°C (-58 to 842°F); and PR-18E (Extreme) operates from -200 to 600°C (-328 to 1112°F). Accuracy is rated Class A across the series, with specific ranges defined as Class A from -50 to 300°C (-58 to 572°F) or else Class B for PR-18H models, and Class A from -100 to 450°C (-148 to 842°F) or else Class B for PR-18E models. All variants utilize a standard TCR of 0.00385 Ω/Ω/°C.

Response time (T90) varies by sheath diameter and model series:

• PR-18L: 2.4 sec for 1/8", 2.8 sec for 3/16", and 3.25 sec for 1/4".
• PR-18H: 2.8 sec for 1/8", 4.11 sec for 3/16", and 5.41 sec for 1/4".
• PR-18E: 9 sec for 1/8", 9.8 sec for 3/16", and 10.6 sec for 1/4".

The probes feature an IP67 ingress protection rating, a sheath made of 316 stainless steel, and are rated for vibration per IEC 60068-2-6 (5 to 2000 Hz sweep rate, one active per minute; number of sweep cycles 10 and acceleration 5g) and shock per IEC 60068-2-27 (50g/11ms).

Configuration Options

The PR-18 series is configurable across several dimensions to meet specific installation requirements:

• Sensor Elements: Available with 100 Ω or 1000 Ω nominal resistance at 0°C.
• Diameters: Sheath diameters of 1/8, 3/16, and 1/4 inch are offered.
• Lengths: Standard probe lengths include 2, 3, 4, 6, 9, 12, 18, and 24 inches. Other lengths may be built using the Omega configurator.
• Process Connection: All models feature a 1/2" NPT thread for mounting into thermowells or direct process connections.
• Housing & Electricals: The aluminum protection head includes a screw terminal block for easy connection of insulated copper extension wire. A flip-top design facilitates access to the terminals.

Additional options include replacement probes (without the protection head assembly) and a spring-loading option, which allows the probe to bottom out in a thermowell for quicker response; however, this option should not be ordered unless a thermowell is used.

Key Product Differences

The series distinguishes itself through three primary model families based on temperature capability:

• PR-18L (Low): Designed for the -50 to 250°C (-58 to 482°F) range with Class A accuracy.
• PR-18H (High): Covers -50 to 450°C (-58 to 842°F), maintaining Class A accuracy from -50 to 300°C (-58 to 572°F) and reverting to Class B above that threshold.
• PR-18E (Extreme): Supports the widest range of -200 to 600°C (-328 to 1112°F), with Class A accuracy from -100 to 450°C (-148 to 842°F) and Class B outside that span.

While all models share the same aluminum protection head, IP67 rating, and 316 stainless steel sheath material, response times increase with higher temperature ranges due to differences in sensor construction or insulation requirements inherent to the PR-18H and PR-18E designs.