US3635092A

US3635092A - Manually operated gas sampler

Info

Publication number: US3635092A
Application number: US875654A
Authority: US
Inventors: Ralph E Maughan; Fred C Ryan
Original assignee: US Department of the Interior
Current assignee: US Department of the Interior
Priority date: 1969-11-12
Filing date: 1969-11-12
Publication date: 1972-01-18
Anticipated expiration: 1989-01-18

Abstract

A pliant sample container housed within a resilient pump is filled with gas by manually compressing and releasing the pump.

Description

1111111001 States Patelm Maugham 01011. [4 11011., W, 1922 [54] MANWALLY OPERATED (9A5 [56] References Cited! @AMWUER UNITED STATES PATENTS [72] g z P' Fred Ryan 2,223,785 12/1940 Hassler ..73/421.5 2,645,940 7/1953 140111 et a1. ...73/421.5 [73] Assignee: The Unlted States. of America as 3,063,296 11/1962 H1161! 6 73/421 5 represented by the secretary of the n, 3,085,439 4/1963 Pnce 73/4215 3,499,326 3/1970 Madier et a1 ..73/421.5 Filed; 1 1959 Primary Examiner--S. Clement Swisher Assistant Examiner-Daniel M. Yasich [2 1] App]. M75654} Attorney-Gersten Sadowsky and Albert A. Kashinski [52] US. U1. ..73/421.5 R, 23/259, 417/148 [57] ABSTRACT [51] 111711.411. ..G0ln 1/24 A phant sample contalner housed wlthm a reslhent pump 1s R, filled i g y manually p i g and releasing h 73/421 R; 417/437, 479, 480, 395, 148; 23/259; pump (1111111110, 11 Dmwmg figure Q 22 m 11 44 E [I] 45 l" N I]: I 111 1 E :{1 24\ I w :1 1

BACKGROUND OF THE INVENTION Air pollution is a growing menace to life and property. In small doses atmospheric contaminants are a tolerable nuisance, but as the dosage and concentration increase they become intolerable. In the confined environments of mines and factories they can even be lethal. Because of this potential danger, the concentration of atmospheric contaminants in inhabited environments must be continually monitored.

Accurate environmental monitoring requires such costly precision equipment and trained operating personnel that duplication of equipment and personnel for numerous sampling areas is impractical. A more workable solution involves removal of sample atmospheres from a local environment to a central test station. For this purpose a gas sampler is required, capable of efficiently and inexpensively sampling and storing a spot atmosphere without contamination or deterioration. Gas samplers available prior to this invention failed to meet one or more of these criteria. One sampler, described by William D. Conner and John N. Nader in the American Industrial Hygiene Association Journal; Volume 25; May-June, 1964 on pages 291-297, avoided contamination and deterioration of the sample, but was bulky and slow, and required an external power source. This invention incorporates the advantages, while eliminating the disadvantages, of the Conner and Nader sampler in a fast acting, efficient and inexpensive sampler.

SUMMARY OF THE INVENTION This invention is a manually operated gas sampler for grab sampling spot atmospheres in a field environment. It includes a pliant, impermeable film, sample container housed within a resilient vacuum pump. Gas enters a sample bag of the container through a duct in a tapered stem, tightly fitted through an opening in the vacuum pump. When the resilient pump is manually compressed, gas in the sample bag is driven out through the stem until the bag is deflated. When the collapsed pump is released, it springs back to normal shape, inflating the bag by drawing a gas sample through the stem.

The volume of gas drawn into the sampler is approximately equal to the difierence between the internal volumes of the resilient pump in the normal and compressed states. If the pump is compressed only enough to completely deflate the sample bag, the final volume of the sample is the same as the volume of gas originally present in the bag. In operation, however, the sample bag is normally loaded into the resilient pump in a partially or totally deflated condition. For this reason, if a full sample is required, it is often necessary to compress the pump more than the amount required to completely deflate the sample bag. To achieve this result, the resilient pump has a relief valve which enables further reduction of the pump volume by allowing gas to escape from the sealed pump chamber when compression of the pump continues after the sample bag is deflated.

Because the relief valve is the only moving component, operation of the gas sampler is extremely dependable. Because the pump body is constructed of a tough, resilient material, the sampler withstands extensive rugged use with little care. The exposed stern portion of the sample container is similarly rugged, while the more delicate sample bag portion of the container is protectively housed within the pump, so that accidental damage to the sample container is unlikely.

Therefore, one object of this invention is a rugged and dependable, self-contained gas sampler.

Another object of this invention is a manually operable gas sampler for sampling spot atmospheres in a field environment.

Still another object of this invention is a gas sampler having an efiicient, inexpensive and easily produced sample container.

These and other objects of the invention will become more fully apparent with reference to the following specification and drawing.

BRIEF DESCRIPTION OF THE DRAWING The sole FIGURE shows a gas sampler in longitudinal cross section.

DESCRIPTION OF THE PREFERRED EMBODIMENT A gas sampler is shown in the sole FIGURE in longitudinal cross section, revealing the internal parts. The sampler includes a sample container 12 housed within a resilient vacuum pump 14. Differential pressure generated by compressing and releasing the resilient pump l4 draws a gas sample into the container 12, isolating the sample for transportation and analysis.

On the sample container 12 there is a conical, tapered inlet stem, or neck 16, through which a gas sample passes to the in terior cavity 18 of the container. Adjacent to its broad end, the stem 16 has a radial shoulder 20, formed by the flat face of a hemispherical stem extension 22. The shoulder 20 joins a closed, pliant sample bag 24, atmospherically sealing the bag except for an opening through a narrow duct 26 on the longitudinal axis of the stem 16. To prevent inadvertent complete sealing of the container 12 should the sample bag 24 cover the opening of the duct 26, narrow slots extend laterally across the curved face of the hemispherical extension 22, intersecting with the duct opening. The slots enlarge the effective area of the opening so that complete closure is unlikely.

For complete atmospheric sealing of the container 12, a cap 28 is threaded to the stem 16. When the container is closed, a flat seal 30 on the cap abuts the duct opening at the narrow end of the stem. The container 112 is emptied, either by removing the cap, or by puncturing this seal. On the side opposite the duct opening, a rubber serum stopper 32 fills an axial cavity in the end of the cap. By inserting a hypodermic needle through the stopper 32 and seal 30, and drawing a sample into a protected environment, the container 12 is evacuated without contaminating the gas sample. When the needle is withdrawn, the serum stopper 32 covers the opening left in the seal 30.

A suitable sample bag 24 for the container 112 is constructed from a single rectangular sheet of pliant, impermeable film, 2 to 3 mills thick. The film is folded over upon itself and sealed at the intersecting edges. Before sealing the bag, an opening is cut near the fold to accommodate the tapered stem 16. The stem is then sealed to the bag by the shoulder 20. When the bag is inflated, it assumes the shape of a pillow, with side and

bottom seams

34 and 36, as shown in the sole FIGURE. Sample containers of other construction are equally suitable.

For collecting a gas sample, the sample container 12 is housed within a resilient pump 14, with the narrow threaded end of the stem 16 protruding into the sample environment. On the pump, a cuplike pump shell 38 is mated at its open end to a cuplike hemispherical bonnet 40, forming a unitary sealed chamber 42. To tightly seal the shell 38 and bonnet 40, without limiting the flexibility of the combined structure, a raised bead 44 on the lip of the shell 38 nests within a complementarily shaped slot, recessed into a thick lip 46 on the bonnet 40. Compression and expansion forces applied to the pump shell are transmitted evenly to the bonnet through this flexible joint.

As seen in the sole FIGURE, the wall thickness of the bonnet 40 is uneven, tapering from a wide lip 46 to a narrower crown 48. Midway between the edge of the lip 46 and the top of the crown 48 on one side of the bonnet, there is a tapered circular opening through the wall of the pump, surrounded by a wide shoulder 50. The tapered sidewalls of the conical stem 16 nest tightly within the opening, joining the container 12 to the pump 14 and preventing any flow of gas through the hole. When the pump is compressed, internal pressure forces the stem 16 tightly against the shoulder 50, improving the seal between them.

Differential pressure for emptying and filling the sample container 12 is created by manually compressing and releasing the resilient pump 14. As the opposite walls of the pump body are compressed, pressure is exerted to collapse the sample bag 24. If the cap 28 is removed from the stem 16, and the pump body is compressed sufficiently, any gas in the bag 24 is driven out through the duct 26. When the resilient pump body is released, it expands to normal shape and a gas sample is drawn through the duct and into the sample container 12.

1f the pump 14 is compressed only enough to completely deflate the sample bag, the gas volume sampled in this way is approximately equal to the difference between the internal volumes of the pump 14 in the normal and compressed states. The same amount of gas enters the bag when the pump is released as was forced out when the pump was compressed. In actual operation, however, the sample container 12 is normally loaded into the resilient pump 14 with the sample bag 24 in a partially or totally deflated condition. To obtain a full sample it is necessary to compress the pump more than the amount required to completely deflate the sample bag 24. This additional reduction of pump volume is obtained by positioning a relief valve 52 near the crown of the pump shell 38. The valve 52 enables maximum volume reduction by allowing gas to escape from the sealed chamber 42 when compression of the pump 14 continues after the sample bag 24 is deflated.

Operation of the relief valve 52 is simple, yet effective. A spherical ball 54 is biased by a spring 56 against a conically tapered hole 58 through the crown of the pump shell 38. The ball 54 and spring 56 are closed by a nozzle 62 within a threaded tube 60 protruding from the pump shell. Gas from the sealed chamber 42 passes through the hole 58 and out an axial duct 64 in the nozzle 62. Tapered threads 66 on the nozzle stem engage a hose (not shown) to carry escaping gas away from the sample environment.

For collecting a gas sample, the sampler is preferably operated as follows: the pump shell 38 and bonnet 40 are separated from one another at the sealing joint. A totally or partially deflated sample container 12, with the cap 28 in place to prevent contamination of the sample container cavity 18, is coupled to the bonnet 40 by inserting the tapered stem 16 through the bonnet hole and pressing it tightly against the supporting shoulder 50. The sample bag 24 is lowered into the pump shell 38, and the shell and bonnet joined together. After removing the stern cap 28, the resilient pump 14 is manually compressed in an area away from the sample environment to completely evacuate the container cavity 18. Gentle pressure on the pump insures complete evacuation of the cavity 18, without forcing gas through the relief valve. When gas flow out of the stem 16 stops, the cap 28 is replaced to prevent contamination. The resilient pump 14 is compressed further to drive as much gas as possible through the relief valve. In this collapsed state the sampler 10 is immersed in a sample environment. When the stem cap 28 is removed, outward flexing of the resilient pump draws a gas sample through the stem 16 as the pump assumes its normal shape. Having returned to normal shape, the pump prevents inadvertent breathing action of the sample bag 24, and impedes any flow of either the sample or alien ambient atmosphere until the stem is capped.

When the volumetric ratio of the container cavity 18 and sealed chamber 42 is properly proportioned, a single compression and expansion of the pump 14 is sufficient to collect a full sample in the container 12. If the cavity is too large in proportion to the sealed chamber, the container is filled completely by sealing the stem 16 with the cap 28 and compressing the pump a second time to drive more gas out of the chamber 42 through the relief valve 52. When the cap 28 is removed from the stern a second time, additional gas is drawn into the container. For this reason, within a wide range the relative sizes of the sample container and resilient pump are critical only in relation to operating convenience.

While the preferred embodiment of the invention has been shown and described, modifications within the scope of this disclosure are expected for adapting the invention to diverse sampling environments. Since possible obvious modifications of the invention are innumerable, and since they will be readily apparent to the skilled worker in the art, the specific details of the disclosed embodiment should not be construed to limit the invention which is defined by the following claims.

What is claimed is:

l. A gas sampler comprising:

a hollow resilient envelope,

a pliant sample container positioned within the envelope to fonn a gastight chamber intermediate the interior of the envelope and the exterior of the sample container,

a passageway extending through the resilient envelope and into the sample container,

a valve on the envelope, biased to allow gas to escape from the chamber when the envelope is compressed by sufficient pressure, but to prevent any gas flow into the chamber, and

a scalable opening in the envelope for removing the sample container from the envelope.

2. A gas sampler as claimed in claim 1 in which the resilient envelope includes a cuplike shell with a sealing rim, and a mated cuplike bonnet with a complementarily shaped sealing rim for joining the bonnet and shell into a closed resilient unit, the junction of the shell and bonnet sealing rims constituting the scalable opening in the envelope.

3. A gas sampler as claimed in claim 2 in which the passageway extends through an elongated, tapered stem, the broad end of which is joined to the pliant sample container and the narrow end of which is shaped for receiving a cap to seal the interior of the sample container, and

the resilient envelope includes a hole surrounded by a raised shoulder for sealing the elongated stern partially within and partially without the resilient envelope.

4. A gas sampler as claimed in claim 3 further comprising a cap for the tapered stem for sealing the interior of the sample container.

5. A gas sampler as claimed in claim 3 in which the broad end of the tapered stem is terminated by a convex extension into the sample container, the extension having radial slots intersecting with the passageway through the tapered stem to enlarge the effective opening area of the passage.

6. A gas sampler comprising:

a hollow, gastight, resilient envelope with sufficient resilience to recover without external stimulus from a compressed to a normally expanded state,

a first opening through a wall of the envelope,

a second opening through a wall of the envelope,

a sample container positioned substantially within the envelope, the sample container including:

a hollow, gastight, pliant sample bag with a smaller volume than the resilient envelope,

a third opening extending through a wall of the sample bag,

a tubular neck sealed to the third opening and extending into sealed communication with the first opening in the resilient envelope, so that any gas passing inward through the first opening is channeled into the sample bag, rather than into the hollow interior of the envelope,

a valve cooperating with the second opening through the resilient envelope to permit gas flow out of the envelope when gas pressure within the envelope exceeds a predetermined minimum, but to prevent any gas flow into the envelope, and

a scalable fourth opening through a wall of the resilient envelope, of sufficient size for inserting the sample container substantially within the envelope.

7. A gas sampler as claimed in claim 6 in which the resilient envelope includes a cuplike shell with a sealing rim, and a mated cuplike bonnet with a complementarily shaped sealing rim for joining the bonnet and shell into a closed resilient unit, the junction of the shell and bonnet sealing rims constituting the scalable fourth opening.

8. A gas sampler as claimed in claim 6 in which the tubular neck comprises an elongated, tapered stem with a longitudinal cap for the tubular stem for sealing the interior of the sample container.

10. A gas sampler as claimed in claim 8 in which the broad end of the tapered stem is terminated by a convex extension into the sample bag, the extension having radial slots intersecting with the longitudinal passage through the tapered stem to enlarge the effective opening area of the passage.

Claims

1. A gas sampler comprising: a hollow resilient envelope, a pliant sample container positioned within the envelope to form a gastight chamber intermediate the interior of the envelope and the exterior of the sample container, a passageway extending through the resilient envelope and into the sample container, a valve on the envelope, biased to allow gas to escape from the chamber when the envelope is compressed by sufficient pressure, but to prevent any gas flow into the chamber, and a sealable opening in the envelope for removing the sample container from the envelope.

2. A gas sampler as claimed in claim 1 in which the resilient envelope includes a cuplike shell with a sealing rim, and a mated cuplike bonnet with a complementarily shaped sealing rim for joining the bonnet and shell into a closed resilient unit, the junction of the shell and bonnet sealing rims constituting the sealable opening in the envelope.

3. A gas sampler as claimed in claim 2 in which the passageway extends through an elongated, tapered stem, the broad end of which is joined to the pliant sample container and the narrow end of which is shaped for receiving a cap to seal the interior of the sample container, and the resilient envelope includes a hole surrounded by a raised shoulder for sealing the elongated stem partially within and partially without the resilient envelope.

6. A gas sampler comprising: a hollow, gastight, resilient envelope with sufficient resilience to recover without external stimulus from a compressed to a normally expanded state, a first opening through a wall of the envelope, a second opening through a wall of the envelope, a sample container positioned substantially within the envelope, the sample container including: a hollow, gastight, pliant sample bag with a smaller volume than the resilient envelope, a third opening extending through a wall of the sample bag, a tubular neck sealed to the third opening and extending into sealed communication with the first opening in the resilient envelope, so that any gas passing inward through the first opening is channeled intO the sample bag, rather than into the hollow interior of the envelope, a valve cooperating with the second opening through the resilient envelope to permit gas flow out of the envelope when gas pressure within the envelope exceeds a predetermined minimum, but to prevent any gas flow into the envelope, and a sealable fourth opening through a wall of the resilient envelope, of sufficient size for inserting the sample container substantially within the envelope.

7. A gas sampler as claimed in claim 6 in which the resilient envelope includes a cuplike shell with a sealing rim, and a mated cuplike bonnet with a complementarily shaped sealing rim for joining the bonnet and shell into a closed resilient unit, the junction of the shell and bonnet sealing rims constituting the sealable fourth opening.

8. A gas sampler as claimed in claim 6 in which the tubular neck comprises an elongated, tapered stem with a longitudinal passage, the broad end of which is joined to the pliant sample bag at the third opening, and the narrow end of which is shaped for receiving a cap to seal the interior of the sample container, and the first opening comprises a hole surrounded by a raised shoulder for sealing the elongated stem partially within and partially without the resilient envelope.

9. A gas sampler as claimed in claim 8 further comprising a cap for the tubular stem for sealing the interior of the sample container.