RTD-Strap-On

Supported Applications

The ACI Platinum Strap-On Series features a 1.5" square copper plate with the sensor encapsulated to the back side of the plate to improve thermal conductivity between the pipe and the sensor. It is used where an immersion-style sensor cannot be inserted into the pipe, clamping directly onto the outside of the pipe as a single-point temperature sensor for electronic controllers in commercial heating and cooling systems.

• Strap-on pipe surface temperature sensing for hydronic and HVAC systems
• Building management and electronic controller inputs
• Retrofit points where immersion probes cannot be installed

Each sensor uses Etched Teflon (PTFE) colored lead wires to differentiate sensor types and is CE, RoHS2 and WEEE compliant. Wiring must not be run in any conduit with line voltage, and applying thermal grease between the sensor plate and pipe is recommended.

Operating Conditions & Performance

The Platinum RTD sensor follows a PTC (Positive Temperature Coefficient) curve to DIN EN 60751 (IEC 751) with a temperature coefficient of 3850 ppm / °C. Output at 0°C is 100 Ohms nominal for the A/100 series and 1000 Ohms nominal for the A/1K series.

• Accuracy: ±0.06% Class A, per the tolerance formula ±°C = (0.15°C + (0.002 * |t|)) where |t| is the absolute value of temperature above or below 0°C in °C. Points include ±0.23°C at -40°C, ±0.15°C at 0°C and ±0.34°C at 93°C.
• Sensor stability: ±0.03% after 1000 Hours @ 300°C.
• Response time: 30 Seconds nominal (63% step change).
• Self-heating / maximum operating current: 100 Ohm RTD is 7 mW/°C in still air at 5 mA; 1K Ohm RTD is 4 mW/°C in still air at 3 mA.

Storage temperature range is -40 to 85°C and operating humidity is 10 to 95% RH, non-condensing. Lead wires are Etched Teflon (PTFE) to MIL-W-16878/4 (Type E), with wire sizes of 14 to 22 AWG. The foam material is a Neoprene/EPDM/SBR Polymer rated UL94-HF1, MIL-R-6130C and FMVSS-302.

Configuration Options

Models differ by RTD element value, wire count, pipe-size configuration, enclosure and calibration certification, so the sensor can be matched to the controller input, pipe diameter and mounting environment.

• Element: 100 = 100 Ohm Platinum RTD or 1K = 1K Ohm Platinum RTD.
• Wires: 2W provides two non-polarity-sensitive wires; 3W provides three polarity-sensitive wires for use with a 3-wire transmitter.
• Configuration: S fits 1 1/4" (32mm) to 4" (100mm) pipe; S10 fits 2" (50mm) to 10" (250mm) pipe.
• Enclosure: GD = Galvanized Steel (-40 to 93°C, NEMA 1 (IP 10)); PB = ABS Plastic (-30 to 85°C, UL94-HB, Plenum Rated); 4X = Polystyrene, NEMA 4X (IP 66) weatherproof (-40 to 70°C).
• NIST: no certificate, or NIST Certificate (3 Points).

Enclosure choice also sets weight: 0.37kg for a Galvanized (GD) unit, 0.19kg for a Plastic (PB) unit and 0.25kg for a NEMA 4X (4X) unit.

Key Product Differences

A full model number is A/ <sensor series> - <model series> - <number of wires> - <configuration> - <enclosure> - <NIST>, for example A/100-2W-S-GD. Standard configurations include:

• A/100-2W-S-GD — 100 Ohm RTD, 2-Wire, Galvanized Enclosure.
• A/100-2W-S-PB — 100 Ohm RTD, 2-Wire, Plastic Enclosure.
• A/100-3W-S-GD — 100 Ohm RTD, 3-Wire, Galvanized Enclosure.
• A/1K-2W-S-GD — 1K Ohm RTD, 2-Wire, Galvanized Enclosure.
• A/1K-3W-S-GD — 1K Ohm RTD, 3-Wire, Galvanized Enclosure.
• A/1K-2W-S10-GD and A/100-3W-S10-GD — S10 configuration for larger 2" to 10" pipe.

Accessories include the A/HOSE CLAMP-2-5" and A/HOSE CLAMP-2-12" quick-release worm-gear clamps and NSG HEAT TRANSFER PASTE in 2OZ and 16OZ sizes.