Paper VT-TuA10
A New Static Expansion System for the Spanish Metrology Center (CEM)

Tuesday, October 21, 2008, 4:40 pm, Room 205

The Spanish Metrology Center, in cooperation with the Technical University of Madrid (UPM) is developing a static expansion system to be used as pressure primary standard in the range from 0,0001 Pa up to 1000 Pa. This standard will be used to calibrate capacitance diaphragm gauges and spinning rotor gauges. The system consists of five vessels: two 100 L-vessels, two 1 L-vessels and one 0,5 L-vessel. It also has two 300 L/s turbopumps (for N2) in order to evacuate the system. The system has been designed to be bakable up to 150 C in order to facilitate its degasification. The system is also endowed with 16 Pt100 temperature probes in order to measure the temperature distribution on the vessels. As auxiliary pressure gauges it also has one mass spectrometer, two ionization gauges, two spinning rotor gauges and two capacitance diaphragm gauges. The expansion factor determination is performed by gas accumulation method. The use of a Ruska 2465 pressure balance and a DHi FPG8601 pressure balance connected to the system through a 1 Torr differential capacitive diaphragm gauge is a special feature of this expansion factor determination. In this way we expect to reduce our measurement uncertainties.