RTD-Immersion

Supported Applications

The ACI Platinum RTD Immersion series consists of single-point temperature sensors designed for use with electronic controllers in commercial heating and cooling building management systems. These immersion probes are intended for installation into a ½" NPT female thread, typically via a Threadolet or Tee, to monitor process conditions.

Documented media compatibility includes:

• Air/Gas/Steam
• Water (No Glycol or other Chemicals)

Operating Conditions & Performance

The series operates within a process temperature range of -40 °C to 200 °C (-40 °F to 392 °F). Ambient operating conditions are rated for -40 °C to 85 °C (-40 °F to 185 °F) with humidity up to 10 % to 95 % RH, non-condensing. Storage temperature is specified as -40 °C to 85 °C (-40 °F to 185 °F).

Performance specifications for the Platinum RTD elements are Class A accuracy:

• @ -40 °C (-40 °F): ± 0.23 °C (± 0.414 °F)
• @ 0 °C (32 °F): ± 0.15 °C (± 0.27 °F)
• @ 200 °C (392 °F): ± 0.55°C (± 1.00 °F)

The nominal response time is 8 seconds for a 63 % step change.

Configuration Options

The series supports multiple configurations across sensor elements, thermowell types, insertion lengths, and enclosure ratings to accommodate diverse installation requirements.

Sensor Elements & Outputs

• Nominal Resistance: 100 Ω or 1 kΩ Platinum RTD
• Wire Configuration: Two-wire (2W) or Three-wire (3W). The three-wire option compensates for external lead wire resistance.
• Lead Wires: Etched Teflon (PTFE) colored leads per Mil Spec 16878/4 Type E with silver-plated copper connectors.

Thermowell Configurations

Sensors are available in three primary configurations regarding the thermowell:

• I (Immersion): Includes a welded ½" NPT male thread thermowell.
• IM (Machined Immersion): Features a machined thermowell intended for moving water or high-pressure service. Machined thermowells of 6 in to 24 in meet ASME PTC 19.3 TW-2016 Code B31.1.
• INW (Immersion No Well): Includes a standard ½" NPS process thread for use with an optional machined thermowell or existing application; the sensor does not include a thermowell.

The probe diameter is 6.35 mm (0.25 in) and sheath material is 304 Stainless Steel. Insertion lengths range from 1" to 24", with specific options including 1", 2.5", 4", 6", 8", 12", 18", and 24".

Enclosures & Ratings

The series offers four enclosure types:

• -GD (Galvanized): Galvanized Steel, NEMA 1 (IP10).
• -PB (Plastic Box): ABS Plastic, UL94-HB, Plenum Rated.
• -BB (Bell Box): Aluminum, Plenum Rated, NEMA 3R.
• -4X: Polystyrene Plastic, UL94-V2, NEMA 4X (IP 66).

The series holds CE, UKCA, RoHS2, and WEEE certifications. Optional NIST Certificates are available.

Pressure & Velocity Ratings

Ratings vary by thermowell type, insertion length, media, and temperature:

• Machined Thermowells (Air/Gas/Steam): Up to 200 bar (2900 PSI) at 537.8 °C (1000 °F).
• Machined Thermowells (Water): Up to 393 bar (5700 PSI) at 20 °C (68 °F).
• Fabricated/Welded Thermowells: Maximum pressure decreases with temperature, ranging from 982 PSI (67.7 Bar) @ 70°F down to 290 PSI (20.0 Bar) @ 1200°F.

Fabricated thermowells are intended for tank or low-to-no flow applications; machined thermowells should be used in moving water or high-pressure service due to fluid velocity and wake frequency factors.

Key Product Differences

The series distinguishes between sensor-only configurations (INW), welded immersion probes (-I), and machined immersion probes (-IM). The INW variants provide a ½" NPS thread for integration with separate thermowells, while -I and -IM variants include the sensing element pre-installed in a stainless steel sheath. Model numbers follow the format A/ - - - - - . For example, A/100-2W-I-2.5"-GD denotes a 100 Ω Platinum RTD with two wires in an immersion configuration with a welded thermowell, 2.5" insertion length, and Galvanized enclosure.

Accessories include NSG Heat Transfer Paste (Item # 102595 or # 140574) to improve thermal response when installing the probe into a thermowell, as well as standalone machined thermowells in various lengths and materials (304 Stainless Steel or 316SS).