ON-900-PROBES

Supported Applications

The Omega ON-900 series comprises precision-interchangeable thermistor sensor and probe assemblies designed for temperature measurement and control. The ten available probe styles address specific installation requirements across biological, industrial, and environmental contexts.

• Biological: Esophageal or rectal temperature measurement; animal apparatus (ON-901, ON-920TA).
• Surface Measurement: Flat surfaces including heat loss monitoring, compressor efficiency checks, piping systems, manifold walls, and bearing surfaces (ON-909, ON-930, ON-950).
• Air/Gas Streams: Air temperature measurement and control; monitoring gas streams; remote air readings in air conditioning ducting and equipment cooling systems (ON-905, ON-906, ON-960).
• Liquid Immersion & Pressurized Systems: Fluids within closed vessels or pressurized pipes using rugged closed-end construction (ON-910, ON-920TA, ON-970).
• Insertion Sensors: High-reliability applications requiring small size and fast time response by inserting into a hole (ON-940).
• Oceanographic & Geographic: Field measurements using rugged, minimum-cost constructions (ON-901).

Operating Conditions & Performance

All probe styles in the ON-900 series share a maximum operating temperature of 100 C (212 F). The sensors utilize precision-interchangeable thermistors with standard accuracy of plus/minus 0.2 C for Types 44004, 44005, 44007, 44006, and 44008. An optional higher-accuracy configuration is available at additional cost using plus/minus 0.1 C interchangeable thermistors (Types 44033, 44030, 44034, 44031, 44032).

Output signals are resistance-based, with standard values of 2252, 3000, 5000, 10,000, or 30,000 ohms @ 25 C. Standard lead lengths for most styles (ON-901 through ON-960) are 300 mm (12 in). The ON-970 style offers standard leads of 12 in with other lengths available upon consultation.

Configuration Options

The series supports ten distinct mechanical configurations to accommodate various mounting and environmental needs. Selection is driven by housing material, process connection type, and lead insulation requirements.

Housing & Wetted Materials

• Vinyl Tip: ON-901 (biological/geographic).
• Epoxy Encapsulated in Stainless Steel: ON-909, ON-950.
• Exposed Epoxy Coated Sensor: Open-end stainless steel housing (ON-905) or economical molded plastic housing (ON-906).
• Screw-Mounted Aluminum Housing: ON-930 for surface applications.
• Molded Plastic Insertion Sensor: ON-940.
• Closed-End Stainless Steel Tube: ON-910, ON-920TA, ON-960 (with welded mounting plate).

Process Connections & Mounting

• NPT Fittings: 1/8 NPT stainless steel fitting for closed-end tubes (ON-910, ON-920TA); 1/8-27 NPT threaded body with hex head (ON-970).
• Screw Mounting: #8-32 UNC-2A threaded body (ON-950); four-screw mounting holes (ON-930); two #6 screw mounting holes on welded plate (ON-960).

Electrical Connections & Leads

• Vinyl Shielded-Jacketed Microphone Cable: ON-901, ON-905, ON-906, ON-910.
• Vinyl Insulated Leads: ON-909.
• PFA Insulated 28 A.W.G. Leads: ON-930, ON-940, ON-950, ON-960, ON-970.
• Detachable Connector: The ON-920TA features a detachable mating connector (ON-920TA) for closed vessels where removable leads are required; other styles feature tinned leads unless specified otherwise.

Key Product Differences

The series is ordered using the format ON-9xx(-TA)-[thermistor type]. The first segment identifies the probe style (e.g., ON-901, ON-970), while the final segment defines the thermistor resistance and interchangeability class.

• Standard Accuracy: Model numbers ending in 44004 through 44008 provide plus/minus 0.2 C interchangeable performance (e.g., ON-901-44004).
• : To obtain plus/minus 0.1 C interchangeability, the thermistor portion of the model number is changed to Types 44033 through 44032 (e.g., ON-901-44033). This option incurs additional cost.
• Lead Length Variations: While most styles are fixed at 305 plus/minus 25 mm (12 plus/minus 1 in), the ON-970 allows for custom lead lengths via factory consultation, as indicated by variants such as ON-970-44004-600.