The liquid pressure thermometer operates based on the principle of liquid thermal expansion.

Filling medium: Liquid (such as silicone oil, xylene, methanol).

Principle: Based on the thermal expansion of liquid.

• Strong signal: The pressure change caused by liquid expansion is large, and the indication is stable.
• Environmental temperature influence: Less affected by environmental temperature because liquid is almost incompressible, and the volume change of liquid in the capillary and the gauge head has little impact on pressure.
• Range: Usually used for -40°C to +200°C.

Due to its characteristics of being less affected by ambient temperature and being stable and reliable, the liquid pressure type thermometer has become the preferred choice for many on-site temperature measurement applications in industries.

• HVAC: Measuring the temperature of hot water, cold water, steam and air for control and monitoring.
• Process industry: On-site indication of the temperature of reactors, storage tanks and pipelines in the chemical, pharmaceutical and food industries.
• Plastic and rubber machinery: Measuring the temperature of the barrel of injection molding machines and extruders.
• Machinery equipment: Monitoring the oil temperature and air temperature of hydraulic systems, lubrication systems and compressed air systems.
• Ships: Monitoring the temperature of engine cooling water and engine oil (with the advantage of vibration resistance).

Liquid pressure thermometers are "reliable and hardworking practitioners" in industrial sites. They have successfully addressed the core difficulty of gas pressure thermometers being sensitive to ambient temperature, providing stable, reliable, and maintenance-free on-site temperature indication within a moderate temperature range. They are one of the most common and classic mechanical thermometers in process industries, quietly performing their duties on countless pumps, tanks, pipelines, and equipment, and are trusted tools for engineers.