Electric Contact Bimetallic Thermometer With Mechanical Display, Easy To Read
The electric contact bimetallic thermometer is a medium and low-temperature measuring instrument that combines on-site temperature indication with electrical signal alarm/control functions.
Advantages
- Dual-function integration: Combines on-site indication and automatic control in one, with a compact structure and a lower cost than the combination of "sensor + transmitter + controller".
- Intuitive and reliable: The pointer indication is clear and intuitive. The mechanical structure has strong anti-interference ability and works stably and reliably.
- No external power supply required: Its indication function is completely mechanical and does not need a power source.
- Adjustable control point: Users can conveniently adjust the control temperature point on-site according to process requirements.
- Simple to use: The wiring and control logic are simple, making it easy to install and maintain.
Core Structure and Key Components
- Bimetallic temperature sensing element: Commonly used combinations include brass + Invar, nickel-chromium alloy + iron-nickel alloy, with a temperature range covering -50 to 800℃. The temperature sensing accuracy directly determines the instrument error.
- Electrical contact mechanism: The moving contact is made of silver alloy material (to reduce contact resistance), and the static contact supports single-point, double-point, or triple-point setting. The contact capacity is typically AC 220V 10A/DC 24V 5A.
- Indicator dial: Available in three diameters: φ60, φ100, and φ150mm. The dial scale accuracy is 1.0 or 1.5 grade, and it supports a red alarm pointer to indicate the set value.
- Protective sleeve: Materials can be selected from carbon steel (WCB), stainless steel (304/316L), and Hastelloy. The wall thickness is 3 to 5mm, with a maximum pressure resistance of ≤25MPa. The protection grade is IP65 (standard) / IP67 (waterproof type).
Core technical parameters
- Measurement range: Conventional -50℃ to 500℃, special high-temperature type up to -80℃ to 800℃, low-temperature type down to -100℃ to 100℃.
- Accuracy grade: Industrial grade 1.5 (commonly used), precision grade 1.0, meeting the measurement requirements of most on-site applications.
- Electrical contact parameters: Contact form supports normally open (NO), normally closed (NC), or changeover contacts, with a maximum switching power of AC 380V 15A (heavy-duty type).
- Insertion length: 50 to 1000mm (customizable), insertion depth should be ≥ 10 times the diameter of the protective tube (to ensure accurate temperature measurement).
- Installation methods: Threaded installation (M27*2, G1/2", etc.), flange installation (DN25, DN40), ferrule installation (suitable for thin-walled pipes).
- Environmental adaptability: Operating environment temperature -20℃ to 60℃, relative humidity ≤ 85%, vibration resistance level ≤ 2.5g (industrial grade).
Typical application scenarios
- Electric contact bimetallic thermometers are widely used in industrial sites where temperature needs to be monitored on-site and simple automatic control is required.
- Energy and power equipment: Measurement of boiler water temperature, turbine lubricating oil temperature, and generator bearing temperature alarm.
- Plastic machinery: Temperature control and alarm for the barrel of injection molding machines and extruders.
- Food and beverage equipment: Temperature control for sterilizers, double-layer pots, and baking equipment.
- Chemical equipment: Temperature monitoring and interlock protection for reactors and storage tanks.
- Drying equipment: Temperature range control for wood and textile drying rooms.
- Others: Any situation where an automatic action is needed when the temperature reaches a certain point.
The electrical contact bimetallic thermometer is a simple, economical and practical "on-site conductor". It perfectly integrates the functions of "eyes" (indication) and "switches" (control) within a single instrument. Although its control accuracy and contact life cannot compare with those of a fully electronic system, it still holds an irreplaceable position in countless industrial scenarios where requirements are not high and on-site automation is needed, thanks to its outstanding reliability, intuitiveness and cost-effectiveness. Remembering its contact capacity limit and using it in conjunction with a relay when in use is the key to ensuring its long-term stable operation.