The Ultimate Guide to Double Points Bimetal Thermometers: How They Work and When to Use Them
In the world of industrial process monitoring, precise temperature control is non-negotiable. While standard thermometers provide essential readings, certain critical applications demand an extra layer of safety and automation. This is where Double Points Bimetal Thermometers come into play, offering a robust solution for triggering alarms or controlling systems at preset temperature points.
Understanding the Bimetal Strip Mechanism
At the core of these instruments lies the classic bimetal strip, a simple yet brilliant temperature sensing element. It consists of two different metals bonded together, each with a distinct coefficient of thermal expansion. As temperature changes, one metal expands or contracts more than the other, causing the strip to coil or uncoil. This mechanical movement is directly translated into a pointer rotation on a calibrated dial, providing a clear, direct reading without the need for external power.
The “Double Points” Advantage: Function and Safety
The defining feature is the integration of two independent adjustable set points within the thermometer head. These set points, often marked by flags on the dial, can be positioned at your desired high and low temperature limits. When the temperature reaches either preset point, a corresponding electrical contact is activated. This allows a single device to monitor a process and send two distinct signals—for instance, one to activate a cooling system at an upper limit and another to trigger a heater or alarm at a lower limit.
Key Applications and Best Use Cases
So, when should you specify a double-points model over a standard indicator? Their primary use is in process control and safety shutdown systems across industries like HVAC, food & beverage, chemical processing, and energy management. They are ideal for monitoring:
• Liquid temperature in storage tanks to prevent freezing or overheating.
• Equipment bearing temperature to avoid costly failures.
• Pipeline processes requiring dual-stage alerts.
Installation and Maintenance Tips
For optimal performance and longevity, proper installation is key. Ensure the stem is immersed to the correct length in the medium. Regular calibration checks against a known standard are recommended to maintain accuracy. The robust design of bimetal thermometers generally requires minimal maintenance, but keeping the dial clean and checking the electrical connections for the set points is good practice.
Frequently Asked Questions (FAQ)
Q: Can double points bimetal thermometers work in vibrating environments?
A: Yes, many models are designed with rugged cases and dampened movements to withstand vibration, making them suitable for industrial settings.
Q: How accurate are these instruments?
A: Typical accuracy for industrial-grade bimetal thermometers is within ±1% to ±2% of full scale. Always check the manufacturer’s specifications for the exact tolerance.
Q: Do they require a power source for temperature indication?
A: No. The temperature reading is purely mechanical. Electrical power is only needed for the set point contacts to signal an external control system or alarm.
Upgrade Your Process Safety Today
Integrating dual-setpoint capability directly into your temperature measurement provides a reliable, fail-safe layer of control. If your application requires vigilant monitoring between two