Development of a temperature controlled container for high accuracy capacitance manometers

National Institute of Metrology of Turkey (UME) has developed a new temperature-controlled container for high accuracy capacitance manometers (CDG). In the proposed design, due to the direct (metal-metal) contact of the temperature-controlled plate of the container with the aluminum shell of the sensor, the influence of the temperature of the electronics on the pressure sensor is minimized. Inside the aluminum shell, the temperature of the pressure sensor can be controlled at any fixed temperature with stability of +/- 2 mK in the temperature range from 15 degrees C to 30 degrees C. The use of a pressure sensor inside an appropriate container minimizes the effect of the ambient temperature on the sensor, eliminates the need for correction for the effect of thermal transpiration and thus improves sensor accuracy. CDGs inside containers showed excellent short-term stability at zero pressure, which does not exceed +/- 5 mPa as well as a maximum drift rate of 0.03 mPa h(-1). The measurement results of ambient temperature influence on CDG's zero showed a maximum change of 0.001% of full scale per degree Celsius. Control of CDG at ambient temperature significantly reduces the effects of thermal transpiration, which increases slightly to a maximum of 0.3% at the lowest pressures.