US3403979A

US3403979A - Auto bubbler pipet

Info

Publication number: US3403979A
Application number: US578005A
Authority: US
Inventors: Guy H Burrell
Original assignee: Burrell Corp
Current assignee: Burrell Corp
Priority date: 1966-09-08
Filing date: 1966-09-08
Publication date: 1968-10-01
Anticipated expiration: 1985-10-01

Description

0d. 1, 1968 G. H, BURRELL 3,403,979

AUTO BUBBLER PIPET Filed Sept. 8, 1966 INVENTOR.

United States Patent Oiiice 3,403,979 Patented Oct. l, 1968 3,403,979 AUTO BUBBLER PIPET Guy H. Burrell, Pittsburgh, Pa., assignor to Burrell Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Sept. 8, 1966, Ser. No. 578,005 1 Claim. (Cl. 23254) ABSTRACT OF THE DISCLOSURE Improvements in gas analysis pipets of the type in which an absorption container and an expansion container are connected for receiving a reagent liquid capable of absorbing specific gaseous compounds from a mixture of gas. The volume change in the gas after passing through the reagent is the basis for calculating the percentage of that component. Shown is a gas analysis pipet in which the capillary tubing land is connecting seal, together with its tapered shape, is designed to prevent abruptly pulling the solution into the manifold and to bring the solution up into the capillary under good control. Also shown is a pipet in which the capillary manifold connecting tubing is sealed in such close proximity to the capillary opening that the volume of dead space inside the taper is minimized. Further shown is a pipet having a single indentation for retaining the ball valve in the chamber to facilitate cleaning by allowing the liquid to run out of the capillary as Well as out of the large opening in the expansion container on inversion.

It is an object of the invention to provide a pipet design in which the ball valve rests on the top rim of a short length of heavy wall capillary tubing sealed into the top of the pipet, the heavy wall permitting sealing the tapered tube in close proximity to the capillary without distorting the latter.

This and other objects of the invention will become more apparent from a consideration of the accompanying drawing constituting a part hereof in Vwhich like reference characters designate like parts and in which:

FIGURE 1 is a front elevational view of a gas analysis pipet embodying the principles of this invention; and

FIGURE 2 a cross-sectional view, partially in elevation, taken along the line 2-2 of FIGURE 1.

In the drawing, the numeral 1 designates an absorption container and the numeral 2 an expansion container, the two being connected by a conduit 3 at the bottom of the containers. Disposed within container 1 is a gas tube 4 sealed to the container wall at 5 and to a heavy glass capillary 6 at 7. The top of the container 1 terminates in a capillary 8 having a gradually tapering wall portion 9 that is provided with a single indent 10. Disposed within the capillary 8 is the heavy glass capillary 6 which extends a short distance yabove the container 1 into the valve chamber designated by the numeral 11. The top rim 12 of the capillary 6 is not ground, but is slightly iire polished when hot with a 1A steel ball mounted on a suitable rod before the main connecting tube 8 is sealed in place. A ground glass ball 13 rests on the rim 12, as shown. The bubbler tube 4 terminates in a ball-shaped spherical end 14 having perforations 15 through which the gas escapes into the absorption chamber designated by the reference numeral 16.

The container 2 is provided with a mouth or opening 17 through which the reagent liquid is charged until the absorption and expansion containers 1 and 2 are each about half full. The liquid absorbent is drawn up to above the valve chamber 11 to a level within the capillary ow passage 8a. The inner chamber 16 of the absorption container is thus full of liquid while the liquid in the expansion container is at a low level slightly above the opening of the connecting conduit 3. In filling the chamber 16, the ball valve 13 is unseated and the bubbler tube 4 is also full of liquid.

When gas is forced into the pipet through passage 8a, the glass ball 13 seals oi the inlet of capillary 6 and the gas is forced through the bubbler tube 4 and the perforations 15 into the absorption chamber 16.

As the gas bubbles from the spherical end 14 through the reagent solution in the absorption container, it will accumulate at the top of chamber 16 but will not unseat the valve 13 because the pressure differential is such that the pressure of the incoming gas through capillary passage 8a retains the ball valve 13 on the seat on the short heavy wall section capillary 6.

When the pressure of the gas charged into the pipet is released, valve 13 will unseat land the accumulated gases in absorption chamber 16 will escape through the passage of the short capillary 6, which may be designated the passage 6a, and the volume change of the gases passing out through passage 8a via manifold to the buret will be noted. Since the space in the valve chamber 11 is limited, ball valve 13 will always effect a sharp seal and accurate measurements of the gas volumes may be made. Because of the design of the heavy walled capillary 6 and its proximate seal with the tapered wall of the capillary 8, no gas is trapped in the valve chamber.

Because of the single indent 10 in the tapered wall 9, the ball valve 13 is restricted in its movement but cannot prevent the flow of the reagent liquid from the pipette, so that it can be readily cleaned by pouring out the reagent fluid through both the mouth 17 and the capillary 8. It is evident that these containers may be readily ushed because of the valve construction.

The tapered wall 9 of the gas chamber portion of capillary 8 assists the analyst in bringing the solution up into the capillary 8 without the hazard of abruptly pulling the solution into the manifold. In other words, there is a gradual rise of the absorbing solution through the tapered section and the analyst will have the rate of rise under good control, which is not possible when the solution goes abruptly from a relatively large chamber directly into the capillary, such as is common construction in prior art devices.

In summary, the pipet construction is such that by the use of the heavy walled capillary 6 that permits sealing it into the top of the pipet without distortion and by means of the tapered Iwall of the valve chamber and the restricted space in said chamber, the volume of dead space inside the chamber is held to a minimum, and by the construction as herein shown and described, the pipet may be cleaned by simply inverting it to permit the liquid to run out of the capillary as well as the charging mouth of the expansion chamber.

Although one embodiment of the invention has been herein illustrated and described, it will be evident to those skilled in the art that various modifications may be made in the details of construction without departing from the principles herein set forth.

II claim:

1. In a bubbler tube type gas -analysis pipet, interconnected absorption and expansion containers, the absorption container having a capillary with a gradually reducing ow passage at its upper end and a bubbler tube extending from said passage into the chamber of said absorption container to adjacent the bottom thereof, said tube having a perforated end, and said pipet having a short heavy Walled capillary communicating with the chamber of said yabsorption container forming a seal with said container wall and extending into the reducing ow passage of said first-named capillary to constitute a valve chamber, and a ball valve for seating on the upper rim of said heavy Walled capillary, said ow passage having a non-symmetrically indented wall portion to limit the References Cited UNITED STATES PATENTS 7/1954 Guild 23--292 5/1935 Matuszak 2,3--292 10 MORRIS lO. WOLK, Primary Examiner.

ELLIOTT A. KATZ, Assistant Examiner.