What is Hermetic Sealing and why is it important? What is Altitude compensation?

Hermetic sealing is a term used to define high airtightness level (or low air leakage rate) of a gas density meter. In gas density meter/monitors, hermetic sealing is required at all levels.

SF6 is a greenhouse gas with significant environmental impact, therefore its leakage is controlled at all stage. Besides the environmental impact, the significance of airtightness in SF6 meters is to ensure the stability and reliability of SF6 meters under various environmental conditions, thereby ensuring the accuracy of their measurement results. The sealing performance of SF6 meters can ensure normal operation in extreme environments such as high pressure and low temperature, avoiding measurement errors caused by gas leakage and affecting the safe operation of power systems.

Besides the airtightness of the airway, the casing of the gas density meter is also hermetically sealed. This is a feature known as Altitude Compensation.

As altitude increases, atmospheric pressure gradually decreases, which could affects the measurement accuracy of SF6 meters by skewing reference pressure in the gauge. Therefore, to compensate for this effect, it is necessary to design the casing of the SF6 meter to be hermetically sealed, which encloses the standard atmospheric pressure gas inside the meter to avoid the influence of external atmospheric pressure and ensure the accuracy and reliability of SF6 meter measurements in high-altitude areas.