DE2349996A1 - PRESSURE RESPONDING VALVE. REMOVAL FROM: 2332967 - Google Patents

Description

Becton Dickinson and Company, East Rutherford, N.J., USA

Pressure sensitive valve

The invention relates to a pressure responsive valve for arrangement in a liquid line, normally soft prevents a flow of liquid, each

but only automatically in one direction if there is a pressure gradient opens and automatically returns to the closed position when there is no longer a pressure gradient in this direction consists.

Such valves are used, for example, in devices for taking blood samples from which blood from a vein sucked through a cannula into a vacuum container will. Since such vacuum containers often contain chemicals for the subsequent blood test that is required for the patient can be harmful, it is necessary to prevent a backflow of liquid from the vacuum container to the patient. Normal ball check valves are not very suitable for this purpose, since they are held in a certain position must be required for the ball to return to its initial closed position under gravity. This return is associated with a time delay, especially since friction between the ball and the housing is usually overcome must be before the ball automatically returns to its closed position. To ensure a secure seal in the closed To ensure position, tight tolerances must be met in the manufacture of the outer surface of the ball and the valve seat are complied with, reducing manufacturing costs

409808/0966

2349396

increase. Spring-loaded ball check valves have the disadvantage that they only have a considerable. ■ Open pressure gradient. If the pressure gradient then decreases, the spring often brings the ball in prematurely their closed position.

The invention is based on the object of creating a pressure-responsive valve of the type mentioned at the beginning, which only requires a low opening force, i.e. opens in one direction even with a small pressure drop closes immediately when this pressure gradient is reduced.

This object is achieved in that the Valve has a housing with a chamber which lies between the ends of the liquid line and contains a thin, elastic disc, the middle part of which is normal * wise sealingly at the mouth of a channel communicating with one end of the liquid line and in the Area of its outer circumference rests against projections that extend into the chamber and the disc in sealing Hold the system at the channel mouth, the disc being released from the channel mouth at a pressure gradient to the other end of the liquid line and between the Voraprtingen deformed and the flow from one to the other releases the other end of the liquid line, but automatically returns to its sealing position at a predetermined increase in the liquid pressure at the other end of the liquid line.

Further details and features of the invention result from the following description, taken in conjunction with the drawings, in which there is shown an embodiment of the invention as applied to a blood collection device. It shows: - ..- ■ '- ■ - "■ - ■ ■' · .-. ■■ - ..

409808/0966

1 shows a longitudinal section through a blood collection device with a valve according to the invention,

FIG. 2 shows a section through the valve of FIG. 1 in the closed state on an enlarged scale,

3 shows a section similar to FIG. 1, the device

is in fluid connection with a vacuum container and the valve is open,

4 shows the valve in the position of FIG. 3 on an enlarged scale, with the arrows indicating the blood flow,

Fig. 5 is a section through the valve along line 5-5 in 4 on an enlarged scale and in a perspective view,

Fig. 6 shows a section similar to Fig. 1, wherein the "valve is closed after a blood sample has been taken and" the vacuum container has been removed and

7 shows the valve in the position of FIG. 6 on an enlarged scale Scale.

Xn Fig. 1 is a cannula unit 20a with a housing 21a shown, which has two cooperating parts, a front part 27a and a rear part 33a. In a longitudinal bore 25a of the front part 27a is a cannula 22a attached. A cannula 23a is corresponding inserted in a longitudinal bore of the rear part 33a. The rear part 33a has an external thread 37a onto which a holder 44a can be screwed. The back end of the holder 44a is open to successively vacuum containers 45a to be able to take up, each of which has a test tube 46a with a

409808/0966

Plug 47 a included. Dae front part 27a and; the rear part 33a of the cannula unit together form an inner chamber 38a (see FIG. 5) . The rear end 29a of the cannula 22a extends into the chamber 38a and cooperates in a sealing manner with the middle section of a thin elastomeric disk 30a. The disk 30a has a curved shape with a flat circumferential ring surface and in its normal position it rests on projections 5Q which extend from the inner end face of the rear housing part 33a into the chamber 38a and are evenly distributed over the circumference. In the exemplary embodiment, four such projections 50 are provided, but any number can be provided.

Xn of the inner end face of the front part 27a are radial Grooves 51 arranged, which are open to the chamber 38a and Form additional sealing points for the disc 30a when it is in its closed position.

The individual work steps when taking a blood sample are shown in FIGS. 1 to 7. In Fig. 1 and 2 is the Disc 30a in the normal closed position, in which the flow of blood from the vein 48 to the vacuum container 45a is prevented. If, according to FIGS. 3 and 4, the vacuum container 45 is coupled to the cannula 23a the vacuum in the container creates a pressure differential between the opposite sides of the resilient washer 30a. the Disk 30a is thereby deformed, so that it is from the rear End 29a of the cannula 22a comes free, and at the same time the portions of the disc 30a that are between adjacent Projections 50 lie in the spaces between pulled into these projections so that a number of passages are formed through which Dlut from the cannula 22a into the chamber 38a and from there through the cannula 23a into the Vacuum container 45a can flow.

AO9808 / 0966

- 5 - 23499-98

If the bridge gradient then decreases or if a pressure builds up in the chamber 38a, sieve the disc 30a again on the end 29a of the cannula 22a and on its outer surface between the projections 50 on the inner end face of the front part 27a to prevent any flow to prevent the chamber 38a into the cannula 22a »This condition naturally also occurs when the vacuum in the container 45a has been released, as in FIG. 6 and 7 shown. The filled container 45a can now be pulled off, but the tip 28a of the front cannula 22a can remain in the vein if it is desired to take further blood samples and direct them to separate collection containers.

The elastomeric material of the valve allows an accurate Control of opening * and closing. The valve deforms already when it is subjected to a small pressure gradient will. This allows the valve to flow into a vacuum container very precisely control when a predetermined liquid snienge should be collected. This is. especially gave way " when taking blood samples.

- claim -

409 808/0966

Claims (1)

Claim Pressure-responsive valve for arrangement in a fluid line, which normally prevents fluid flow, but only closes in the event of a pressure gradient automatically opens in one direction and automatically in that closed position returns when there is no longer a pressure gradient in this direction, marked by a housing (21a) with a chamber (38a) which lies between the ends of the liquid line and contains a thin, elastic disc (30a), the middle part of which is normally sealingly at the mouth (29a) one with the one End of the liquid line communicating channel (22a) and in the region of its outer circumference on projections (50) which extend into the chamber (38a) and hold the disc (30a) in sealing contact with the channel mouth (29a), the disc (30a) moving away from the other end of the liquid line in the event of a pressure gradient Channel mouth (29a) lifts and deforms between the projections (50) and the Dlirehfluß from one to the other At the end of the liquid line, but if there is a pre- certain increase in the fluid pressure at the other end of the fluid line automatically returns to its sealing position. 409803/0986