Measuring and testing – Sampler – sample handling – etc. – With constituent separation
Reexamination Certificate
2000-11-14
2001-11-27
Noland, Thomas P. (Department: 2856)
Measuring and testing
Sampler, sample handling, etc.
With constituent separation
Reexamination Certificate
active
06321609
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to sampling devices for determining the nature and quantity of chemical and biological contaminants in air and other gases.
More specifically, this invention concerns a gas sampling system that includes a sample trapping module, a magazine holding a plurality of collector-filled sampling tubes, a control that operates the trapping module, and an interface to analytical instruments.
DESCRIPTION OF RELATED ART
There is a large and continuing need for identifying and monitoring the level of pollutants in air and in industrial gas streams. In the past this task was usually performed by obtaining a sample of the air at the monitoring site, and transporting that sample to a laboratory for analysis. Samples were ordinarily obtained by manually filling a sampling container, such as a plastic bag, a hypodermic syringe, or an evacuated metal or glass vessel, and sealing it for transport.
That approach was very expensive, particularly in terms of the personnel needed for periodically taking samples over a long time interval. Consequently, there was developed a number of sampling devices for collecting air samples at predetermined intervals over an extended time period. One such device is shown in the Griffith patent, U.S. Pat. No. 3,884,081. The Griffith sampler uses a plurality of piston pumps that may be hypodermic syringes of appropriate capacity. The plunger of each pump is retracted by mechanical means at a scheduled time to draw an air sample into the pump barrel.
Another sampler that operates in the same general fashion is disclosed in U.S. Pat. No. 3,540.261, to Scoggins. Scoggins provides a magazine containing a number of individual sample containers. The magazine is powered by a time controlled drive system that sequentially indexes the sample containers into registry with a monitoring station where each container is connected with a vacuum source that draws a gas sample through the container, and stores the sample for further processing.
Sampling devices that take a bulk air sample for transport and later analysis are often inappropriate for use in those circumstances in which the contaminant being monitored is present in small concentration, in the parts per million or even parts per billion range. The size of the sample that is collected is often too small for the contaminant to be detected and its concentration measured. That requirement has led to the development of sampling devices which employ sample containers that preferentially extract a contaminant from the sampled gas stream, and hold the trapped contaminant for later release and analysis.
Two patents illustrate that approach to sampling. The first is a patent to Galen, U.S. Pat. No. 4,584,887, which discloses a sampling system having a sample module that may be detached from a flow assembly module. The sample module includes a plurality of small parallel tubes arranged longitudinally about the periphery of a circular frame. Each tube contains a sorbent material that functions to extract and hold contaminants from an air stream passing through the tube. Because most contaminants of interest are organic compounds, the sorbent material is chosen to adsorb those compounds while allowing inorganic compounds to pass through the tube substantially unimpeded. In use, the sample module is mated with the flow assembly module, and sample tubes are sequentially indexed to and connected in series with the sampler inlet and exhaust ports of the flow assembly module by means of a selector valve. A predetermined volume of air is then pumped through the indexed sample tube, and the airborne contaminants are trapped on the sorbent material.
The second patent of interest here is U.S. Pat. No. 4,869,117 that issued to McAndless et al. Like Galen, the McAndless patent uses a cylindrical sample magazine which holds a plurality of small sample tubes that are packed with a solid adsorbent. The sample tubes are symmetrically arranged in a circle about the longitudinal axis of the magazine. The McAndless device differs from that of Galen in that the individual sample tubes are not isolated from each other by way of valve means. Instead, McAndless et al provide a sampling inlet and outlet extending through the magazine housing at a sampling position. Individual tubes are sequentially advanced to and then from the sampling position. While at the sampling position, both ends of the sample tube are sealed so that the tube is positioned in series between the sample source and an air pump which draws an air sample through the tube.
Finally, Lawrence in a paper published in the
Journal of Chromatography
, 395 (1987) 531-538, Elsevier Science Publishers, describes an interface for transferring high boiling compounds from a sample adsorption tube to the column of a gas chromatograph for analysis. The sample tubes described and illustrated by Lawrence are generally similar to those used by McAndless et al.
Despite the developments in sampling techniques described in the prior art, there still exists a need for systems that can obtain a large number of samples at remote and unattended locations, and maintain the integrity of each sample taken until analysis is complete. The system of this invention fills that need.
SUMMARY OF THE INVENTION
The sampling system of this invention includes a sample trapping module, a magazine, sample tubes, and an interface means that functions to enable cooperation between the magazine, the sample tubes and an analytical instrument. The sample trapping module is arranged to hold the magazine during sampling, to sequentially index sample tubes into and out of sampling position within the magazine, to monitor sampling conditions and to collate that data with each individual sample, and to accept control instructions from non-volatile memory carried in the magazine. In turn, the magazine houses a plurality of individual sampling tubes and contains memory means adapted to control operation of the trapping module and to accept and preserve data relating to the samples that are taken by the sample trapping module. Sample tubes used in the invention consist of elongated, sealed tubes which contain a solid collector material that can selectively remove a chemical or biological contaminant of interest from a gas stream that is passed through the tube. Lastly, the interface means is arranged to facilitate the removal of sample tubes from the magazine, and to release contaminants from the collector material contained within the sampling tubes for analysis using conventional procedures.
Hence, it is an object of this invention to provide an unattended, integrated sampling system for repeatedly sampling a gas or air stream at predetermined times to concentrate and collect chemical and biological contaminants for later analysis.
It is a further object of this invention to provide a novel sampling magazine that is arranged to house a plurality of sampling tubes, and which contains non-volatile memory that controls the sampling process and stores data relating to the sample taken by each individual sampling tube.
Yet another object of this invention is to provide a novel sampling tube for use in the sampling system.
Other objects of this invention will be evident from the following detailed description of the invention.
REFERENCES:
patent: 2699679 (1955-01-01), Munger
patent: 3540261 (1970-11-01), Scoggins
patent: 3614434 (1971-10-01), Horwitz et al.
patent: 3841160 (1974-10-01), Iwao
patent: 3884081 (1975-05-01), Griffith
patent: 4274285 (1981-06-01), Purgold
patent: 4584887 (1986-04-01), Galan
patent: 4615224 (1986-10-01), Smith et al.
patent: 4864117 (1989-09-01), McAndless et al.
patent: 4881183 (1989-11-01), Groe
patent: 5553508 (1996-09-01), Dabberdt et al.
patent: 5866072 (1999-02-01), Bowe, Jr. et al.
patent: 5965887 (1999-10-01), Patton
patent: 57-172237 (1982-10-01), None
patent: 10-47689 (1998-02-01), None
A. H. Lawrence, “Simple Interface for Transferring High-Boiling, Compounds from Sample Adsorption Tubes onto Capillary Gas Chromatographic Colums”Journal of Chroma
Albro Thomas G.
Berends, Jr. John C.
Marshall Robert S.
Mengel R. William
Sloop Christopher D.
EAI Coporation
Noland Thomas P.
Shubert Roland H.
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