PRESSURE MODULATION ANALYZER

PURPOSE:To modulate the pressure in a measuring cell positively regardless of the pressure of sample gas by providing a measuring pipe in the upstream of the measuring cell for a sample line, coupling a high pressure supply means with a branch line in the upstream of the measuring pipe, and operating an ON/OFF valve. CONSTITUTION:A measuring cell 2 is coupled with a sample line 1 for introducing a sample gas and a measuring pipe 5 is provided in the upstream of the measuring cell 2. The sample line 1 is coupled, in the upstream of the measuring pipe 5, with a branch line 6 which is coupled with a high pressure supply means, i.e., an N2 gas cylinder 7. The volume V of the measuring pipe 5, the pressure P of the N2 gas cylinder 7, and the volume Vc of the measuring cell 2 are then set to satisfy the relationship V>VcXP, and ON/OFF valves 8, 9, 10 are switched to produce a modulated pressure in the cell. The sample gas itself is not required to satisfy any condition and a modulation efficiency corresponding to the volume of the measuring pipe 5 can be ensured so long as the pressure of the cylinder 7 is higher than a predetermined level.