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FRP3 Immersion Temperature Sensors
The FRP3 sensor design is commonly found in many gas-fired hot-water boilers. Through being manufactured in high-volumes, this sensor is relatively low-cost and so can be utilised across a range of temperature sensing applications.
The FRP3 sensor is generally supplied with an 1/8″BSPG thread and integral connector, though metric threads and flexible lead-wire options are also readily available. This sensor can be supplied with various NTC thermistors or with Pt100/Pt1000 platinum elements.
These immersion sensors are available in brass, nickel-plated brass or stainless steel with a typical time constant (Tc) of around 5 seconds.
Applications
- Gas hot water boilers
- Heating and air conditioning systems
- Instantaneous hot water heaters
- Air compressors and diesel generators
Features
- Fast response design (Tc ≤ 5s)
- Accuracy ±1%, available ±0.2K (0-70°C)
- Operating range up to -40°C/ +125°C
- Interchangeable NTCs or PRTDs
- Connector or lead-wire options
- Various housing materials


Technical Specifications
NTC Thermistor Series | AT-2, ATC3, ET, GT, ATCS, SP |
Temperature Range | -40°C/+125°C depending on NTC |
Sensor Accuracy | R25±3% as standard, ±1% available |
Sensor Material | Nickel-plated brass, brass, stainless steel |
Lead Wires | Integral as a special option |
Connectors | Lumberg 2.5 MSF, Tyco Modu, etc |