Browse Prior Art Database

Gas Dilution System

IP.com Disclosure Number: IPCOM000085874D
Original Publication Date: 1976-Jun-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Dobrowolski, R: AUTHOR

Abstract

Certain analytical instruments are designed to detect or analyze minute quantities of trace constituents of a gas. An example is a plasma chromatograph such as shown in U.S. Patent 3,699,333. In some instances, it is necessary that the sample to be detected be diluted prior to introduction to into the analyzing instrument. Shown are two different gas dilution systems for simply and accurately preparing gas streams containing known concentrations of a sample vapor.

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Gas Dilution System

Certain analytical instruments are designed to detect or analyze minute quantities of trace constituents of a gas. An example is a plasma chromatograph such as shown in U.S. Patent 3,699,333. In some instances, it is necessary that the sample to be detected be diluted prior to introduction to into the analyzing instrument. Shown are two different gas dilution systems for simply and accurately preparing gas streams containing known concentrations of a sample vapor.

Each system utilizes thermal mass flowmeters/flow controllers (FC) to obtain dilute vapor concentrations from a sample source in series with a flowing carrier gas. Typically such a source might be a permeation tube (PT) providing a constant rate of sample release. Dilution is then accomplished in two steps:

1. The carrier gas input to PT is controlled by FC1, resulting in the normal dilution associated with a flow independent source feeding into a carrier stream. Dilution, in this case, is described by the relation C(1) = K/F, where K is a constant incorporating the rate of sample release, F(1) is the carrier flow rate into the permeation tube, and C(1) is the resulting concentration in units determined by K.

2. The second step in the dilution process is accomplished by venting a portion of the output from PT. This is done via a valve V in series with a second flowmeter/flow controller FC2, as shown in Fig. 1. By adjusting valve V to permit sufficient venting of the carrier gas, it i...