Process and apparatus for furnishing gas to a high sensitivity analyzer

A process for providing to at least one high sensitivity analyzer (a.sub.i) small quantities of a first gas (A) contained in a second gas, comprising:

• dividing a primary flow (Q) of the second gas into a first flow (q.sub.1) and a second flow (q.sub.2) greater than the first flow, introducing into the first flow (q.sub.1) a predetermined quantity of the first gas (A) to constitute a first mixture (M.sub.1), dividing the second flow (q.sub.2) into a third flow (q.sub.3) and into a fourth flow (q.sub.4) larger than said third flow, combining the third flow (q.sub.3) with the first mixture (M.sub.1) to constitute a second mixture (M.sub.2), dividing the second mixture into a first part and a second part, supplying said first part to a first utilization outlet (U.sub.1) for supply to the analyzer, combining said second part with a portion of the fourth flow to constitute a third mixture (M.sub.3), supplying the third mixture to a second utilization outlet (U.sub.2) for supply to an analyzer, dividing the fourth flow (q.sub.4) into a fifth flow (q.sub.5) constituting said portion of the fourth flow for combining with the second part of the second mixture, and into a sixth flow (q.sub.6) larger than said fifth flow, withdrawing a portion of the third mixture before supplying the third mixture to the second utilization outlet (U.sub.2), combining at least a portion of the sixth flow with the withdrawn portion of the third mixture to constitute a fourth mixture (M.sub.4), supplying said fourth mixture to a third utilization outlet (U.sub.3) for supply to an analyzer, dividing the sixth flow (q.sub.6) into a seventh flow (q.sub.7), constituting said portion of the sixth flow for combining with the withdrawn portion of the third mixture, and into an eighth flow (q.sub.8) larger than the seventh flow, withdrawing a portion of the fourth mixture before supplying the fourth mixture to the third utilization outlet (U.sub.3), combining at least a portion of the eighth flow with part of the withdrawn portion of the fourth mixture to constitute a fifth mixture (M.sub.5), supplying said fifth mixture to a fourth utilization outlet (U.sub.4) for supply to an analyzer, dividing the eighth flow (q.sub.8) into a ninth flow (q.sub.9), constituting said portion of the eighth flow for combining with part of the withdrawn portion from the fourth mixture, and into a tenth flow (q.sub.10), passing the tenth flow through a cryogenic trap, combining the tenth flow with another part of the withdrawn portion of the fourth mixture, and supplying the mixture thus formed to a fifth utilization outlet (U.sub.5) for supply to an analyzer.