Therm-Probe-Only

Supported Applications

The ACI Thermistor Probe Only Series consists of temperature sensors designed for use with electronic controllers in commercial heating and cooling building management systems. The series is engineered to monitor air temperature in duct applications or immersion applications when installed within a proper length thermowell. These bullet-style probes are not intended for full submersion in water.

Installation guidance specifies avoiding external walls, air registers, diffusers, vents, windows, and heat sources such as lamps, radiators, direct sunlight, copiers, chimney walls, or walls concealing hot-water pipes. The sensors feature a double encapsulation process using thermally conductive epoxy to eliminate moisture effects.

Operating Conditions & Performance

The series operates within an ambient temperature range of -40 to 150°C (-40 to 302°F) for standard thermistor configurations. Storage is supported from -40 to 85°C (-40 to 185°F). Operating humidity ranges from 10 to 95% RH, non-condensing.

Accuracy varies by sensor element and temperature point:

• A/1.8K Series: ±0.5°C (±0.9°F) at 25°C (77°F); tolerance also listed as ±1.0°C (±1.8°F).
• All other thermistors: ±0.2°C (±0.36°F), except the A/10K-E1 Series which is rated at ±0.3°C (±0.54°F).

The nominal response time for a 63% step change is 10 seconds. The probe sheath material is 304 Stainless Steel with a diameter of 0.25" (6.35 mm). Standard lead wire insulation utilizes Etched Teflon (PTFE) rated MIL-W-16878/4 (Type E), suitable for indoor and outdoor wet locations, oil, moisture, acids, oils, sunlight, abrasion, and acid resistance.

Configuration Options

The series offers extensive configuration options across sensor types, probe lengths, lead wire specifications, and certifications. The following capabilities are documented for the full envelope:

• Sensor Elements & Nominal Resistance (at 25°C/77°F unless noted): A/1.8K (1.8 KΩ), A/3K (3 KΩ), A/AN Type III (10 KΩ), A/AN-BC (5.238 KΩ), A/CP Type II (10 KΩ), A/CSI (10 KΩ), A/10KS (10 KΩ), A/10K-E1 (10 KΩ), A/20K (20 KΩ), A/50K (50 KΩ), and A/100KS (100 KΩ).
• Probe Lengths: 2", 4", 6", 8", 12", and 18" insertion lengths.
• Lead Wire Options: Standard colored leads in Etched PTFE (lengths of 14" or 24" depending on probe size) or Plenum Rated Cable options including 6', 10', and 20' CL2P cables. Conductor materials include Silver Plated Copper for standard wire and Tinned Copper for plenum wire.
• Approvals: CE, RoHS2, WEEE.
• Certifications: NIST Certificate (3 Points) available as an option.

Electrical connections are two-wire and non-polarity sensitive. Accessories include NSG Heat Transfer Paste in 2 oz or 16 oz containers for thermal interface applications.

Key Product Differences

Variants within the series differ primarily by sensor curve, probe insertion length, lead wire type/length, and optional NIST certification. The model number structure follows the format: A/[Model Series]-PO-[Probe Length]-[Lead Wire Options]-NIST.

• Standard vs. Plenum Wiring: Standard configurations use Etched Teflon (PTFE) colored leads, while plenum-rated options utilize CL2P FEP cable suitable for indoor and outdoor wet locations with resistance to oil, gas, sunlight, abrasion, and acid.
• Sensor Specifics: The A/1.8K Series has a power dissipation constant of 1 mW/°C, whereas the standard is 3 mW/°C (A/10K-E1 Series: 2 mW/°C).
• Dimensional Notes: Probes with lengths of 6" and under do not feature a flare.