Balco-Immersion

Supported Applications

The ACI Balco Immersion Series is a single-point temperature sensor designed for use with electronic controllers in commercial heating and cooling building management systems. The series features a PTC (Positive Temperature Coefficient) RTD element manufactured using a double encapsulation process to eliminate moisture effects and increase thermal response times via thermally conductive epoxy.

Documented applications include:

• Chilled Water Systems
• Hot Water Systems
• Boilers
• Pumps
• Compressors
• Chillers

The sensor is suitable for media including Air/Gas/Steam and Water. It is intended for installation into a ½" NPT female thread, typically via a Threadolet or Tee.

Operating Conditions & Performance

The Balco RTD Immersion series operates within an ambient temperature range of -40 to 85°C (-40 to 185°F) and supports process temperatures from -40 to 121°C (-40 to 250°F). The sensor maintains stability of +/- 0.05% after 1000 Hours @ 150°C (302°F).

Performance specifications include:

• Sensor Output: 1000 Ohms nominal at 70°F (21°C)
• Accuracy: +/- 1% @ 70°F (21°C)
• Temperature Coefficient: 4618 ppm/°C (0-100°C range)
• Response Time: 8 Seconds nominal (63% Step Change)
• Operating Current: Maximum 5 mA
• Humidity Rating: 10 to 95% RH, non-condensing

The probe diameter is 0.250" (6.35mm) with a thermowell bore of 0.260". The sheath and standard thermowell material are 304 Stainless Steel.

Configuration Options

The series offers configurable insertion lengths, enclosure types, and thermowell constructions to accommodate specific installation requirements.

Thermowell Configurations & Insertion Lengths

• -I (Welded Thermowell): Standard welded construction. Available in 2.5", 4", and 6" insertion lengths. Note: Fabricated thermowells are intended for tank or low-to-no flow applications.
• -IM (Machined Thermowell): Machined from solid bar stock, suitable for moving water or high-pressure service where fluid velocity is a factor. Available in 1", 2.5", 4", 6", and 8" insertion lengths; also available in 316 Stainless Steel.
• -INW (No Thermowell): Includes the sensor probe with a standard ½" NPS process thread for use with an optional machined thermowell or existing installation. Available in 2.5", 4", and 6" insertion lengths.

Housing & Enclosure Options

• -GD (Galvanized): Galvanized Steel; -40 to 121°C (-40 to 250°F); NEMA 1 (IP10).
• -PB (Plastic Box): ABS Plastic, UL94-HB; -30 to 90°C (-22 to 194°F); Plenum Rated.
• -BB (Bell Box): Aluminum; -40 to 121°C (-40 to 250°F); Plenum Rated, NEMA 3R.
• -4X: Polystyrene Plastic, UL94-V2; -40 to 70°C (-40 to 158°F); NEMA 4X (IP 66).

Process Connections & Electricals

The sensor features a two-wire connection that is non-polarity sensitive. Lead wires are 22 AWG (0.65mm) with Etched Teflon insulation, colored Orange/Yellow for the Balco RTD element. The process thread is ½" NPS (National Pipe Straight) Female Thread or ½" NPT (National Pipe Tapered) Male Thread depending on configuration.

Key Product Differences

Variants within the series are distinguished by thermowell construction, insertion length, and enclosure rating. The "-I" suffix denotes a welded thermowell intended for static or low-flow environments such as tanks. In contrast, the "-IM" designation indicates a machined thermowell designed to withstand higher fluid velocities in moving water applications.

The "-INW" configuration provides the sensor probe without an integrated thermowell, allowing installation into existing wells or with separately ordered machined accessories (e.g., A/M1", A/M2.5", etc.). Enclosure selection determines environmental protection: NEMA 4X offers IP66 rating for washdown environments but is limited to a maximum ambient of 70°C (-40 to 158°F), whereas Galvanized and Aluminum enclosures support higher temperatures up to 121°C.

Optional accessories include thermal grease (Item #102595 or #140574) for improved heat transfer, NIST certificates of calibration, and various machined thermowell lengths in 304 or 316 Stainless Steel. The series is covered by ACI's Five-Year Limited Warranty.