Therm-Immersion

Supported Applications

The ACI Thermistor Immersion Series is a single-point temperature sensor designed for use with electronic controllers in commercial heating and cooling building management systems. It is intended for installation into a ½ in NPT female thread, typically via a Threadolet or Tee, and can be installed in a range of enclosures for pipe- and duct-mounted process temperature monitoring.

The series measures the temperature of Air/Gas/Steam and Water media. Each sensor features a 6.35 mm stainless steel probe and is manufactured using ACI's proven double encapsulation process to eliminate the effects of moisture. When paired with a thermowell, the sensor thermowell should be installed against the flow of the water where the temperature is well mixed with no stratification, and the tip of the thermowell should be located in the middle of the pipe. The devices carry CE, UKCA, RoHS2, and WEEE conformance.

Installation note: Do not run the wiring in any conduit with line voltage. Apply thermal grease to the end of the probe before installation into a thermowell.

Operating Conditions & Performance

The sensor operates across a temperature range of -40 °C to 150 °C (-40 °F to 302 °F), with a storage range of -40 °C to 85 °C (-40 °F to 185 °F) and an operating humidity range of 10 % to 95 % RH, non-condensing.

• Sensor type: Thermistor with a Non-Linear, NTC (Negative Temperature Coefficient) curve, one sensing point.
• Accuracy (0 °C to 70 °C): ±0.2 °C, except the A/10K-E1 Series at ±0.3 °C and the A/1.8K Series at ±0.5 °C at 25 °C.
• Response time: 10 seconds nominal (63 % Step Change).
• Power dissipation constant: 3 mW / °C, except the A/1.8K Series at 1 mW / °C and the A/10K-E1 Series at 2 mW / °C.

The probe and thermowell are constructed from 304 Stainless Steel, with a probe diameter of 6.35 mm. Electrical connection is made through two non-polarity-sensitive wires with Etched Teflon (PTFE) insulation, sized 0.65 mm (22 AWG); the color-coded leads are 35.6 mm and differentiate the sensor types. The process connection is a ½ in NPS (National Pipe Straight) female thread or ½ in NPT (National Pipe Tapered) male thread.

When installed in a two-part fabricated welded thermowell, 304/316 SS is rated from 67.7 Bar (982 PSI) at 21.1 °C (70 °F) down to 20.0 Bar (290 PSI) at 648.9 °C (1200 °F), passing through 56.6 Bar (820 PSI) at 93.3 °C (200 °F) and 46.5 Bar (675 PSI) at 204.4 °C (400 °F). Maximum fluid velocity for a welded thermowell in water is 26.8 m/s (88 ft/s) at 63.5 mm (2.5 in) insertion, decreasing to 6.1 m/s (20 ft/s) at 101.6 mm (4.0 in) and 3.05 m/s (10 ft/s) at 152.4 mm (6.0 in) insertion.

Configuration Options

Models differ by sensor output curve, mounting configuration, insertion length, and enclosure. The order code follows the pattern A/ <Model Series> - <Configuration> - <Insertion Length> - <Enclosure> - <NIST>.

Sensor output (Model Series)

Each model series delivers a distinct nominal output at 25 °C with unique lead-wire colors:

• A/1.8K: 1.8 kΩ nominal (Red/Yellow).
• A/3K: 3 kΩ nominal (White/Brown).
• A/AN (Type III): 10 kΩ nominal (White/White).
• A/AN-BC: 5.238 kΩ nominal (White/Yellow).
• A/CP (Type II): 10 kΩ nominal (Brown/Green).
• A/CSI: 10 KΩ nominal (Green/Yellow).
• A/50K: 50KΩ nominal (Brown/Yellow).

The full model-series selection comprises 1.8K, 3K, AN, AN-BC, CP, CSI, 10KS, 10K-E1, 20K, and 100KS.

Configuration

• I: Immersion with Welded Thermowell.
• IM: Immersion with Machined Thermowell.
• INW: Immersion without Thermowell.

Insertion length

Insertion lengths are 25.4 mm (1 in), 63.5 mm (2.5 in), 101.6 mm (4 in), 152.4 mm (6 in), 203.2 mm (8 in), 304.8 mm (12 in), 457.2 mm (18 in), and 609.6 mm (24 in).

Enclosure

• -GD: Galvanized Steel, -40 °C to 121 °C (-40 °F to 250 °F), NEMA 1 (IP10).
• -PB: ABS Plastic, -30 °C to 100 °C, Plenum Rated.
• -BB: Aluminum, -40 °C to 121 °C (-40 °F to 250 °F), Plenum Rated, NEMA 3R (IP 14).
• -4X: Polystyrene Plastic, UL94-V2, -40 °C to 70 °C (-40 °F to 158 °F), NEMA 4X (IP 66).

An optional NIST calibration certificate can be appended to any configuration.

Key Product Differences

The Immersion Series is offered in a large build-to-order matrix of sensor output, configuration, insertion length, and enclosure combinations. Representative catalog models include:

• A/0.1AN-I-2.5"-GD and A/0.1AN-I-2.5"-PB — AN (Type III) sensor, welded-thermowell immersion, 2.5" insertion.
• A/0.1AN-I-2.5"-PB-NIST — same build with a NIST certificate appended.
• A/0.1AN-I-4"-PB and A/0.1AN-I-6"-GD — longer 4" and 6" welded-thermowell insertions.
• A/0.1AN-IM-4"-4X — machined-thermowell immersion in the NEMA 4X polystyrene enclosure.
• A/0.1AN-INW-4"-BB, A/0.1AN-INW-4"-GD, A/0.1AN-INW-6"-GD and A/0.1AN-INW-6"-GD-NIST — sensor-only (no thermowell) builds.
• A/0.1CP-I-2.5"-4X, A/0.1CP-I-4"-GD, A/0.1CP-I-6"-GD and A/0.1CP-I-6"-4X-NIST — CP (Type II) sensor, welded-thermowell immersion.
• A/0.1CP-IM-2.5"-4X, A/0.1CP-IM-4"-4X and A/0.1CP-IM-8"-4X — CP machined-thermowell immersion up to 8" insertion.
• A/0.1CP-INW-12"-GD, A/0.1CP-INW-2.5"-BB and A/0.1CP-INW-4"-PB — CP sensor-only builds across enclosure styles.
• A/1.8K-I-2.5"-4X, A/1.8K-I-4"-BB, A/1.8K-I-6"-PB and A/1.8K-I-6"-GD — 1.8K sensor, welded-thermowell immersion.
• A/1.8K-IM-2.5"-GD, A/1.8K-IM-4"-PB and A/1.8K-IM-8"-PB — 1.8K machined-thermowell immersion.
• A/1.8K-INW-12"-GD, A/1.8K-INW-2.5"-BB and A/1.8K-INW-4"-4X — 1.8K sensor-only builds.

In total the series spans 450 configured part numbers across the documented model-series, configuration, insertion-length, and enclosure options.