Title:
Safety and alarm device for monitoring gas
United States Patent 3910222


Abstract:
A safety and alarm device for monitoring a supply of gas for example in an anaesthetic apparatus. The device has main and secondary gas circuits supplying oxygen and nitrogen protoxide, for example, respectively. The device comprises a cylindrical body housing a piston moved by pressure of the main gas above a predetermined minimum to a normal working position in which a double-port poppet valve movable with the piston prevents supply of secondary gas to a whistle alarm while allowing secondary gas to be supplied to a patient, for example. When the pressure of the main gas falls below the predetermined minimum the piston moves under spring bias from the normal working position to a position in which the poppet valve shuts off the supply of secondary gas to the patient and redirects the secondary gas to the whistle alarm to indicate that the main gas pressure has fallen to a dangerous level.



Inventors:
METIVIER ROBERT
Application Number:
05/406470
Publication Date:
10/07/1975
Filing Date:
10/15/1973
Assignee:
METIVIER; ROBERT
Primary Class:
Other Classes:
124/73, 128/202.22, 137/557
International Classes:
A61M16/00; A61M16/10; F16K17/20; (IPC1-7): G01L19/12; A61M16/00
Field of Search:
116/70 128
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Primary Examiner:
Queisser, Richard C.
Assistant Examiner:
Yasich, Daniel M.
Attorney, Agent or Firm:
Burns, Robert Lobato Emmanuel Adams Bruce E. J. L.
Claims:
I claim

1. A safety and alarm device for combined, main and auxiliary gas supply systems, comprising;

2. A device according to claim 1 in which said housing is cylindrical and said first end portion of the housing has a greater internal diameter than said itermediate portion; said piston comprising two piston portions of external diameters corresponding respectively to the internal diameter of the first end portion and of the intermediate portion of the housing.

3. A device according to claim 2 in which the piston has two seal ring means axially spaced apart, one adjacent the first end portion of the housing and the other in the intermediate portion of the housing; the housing having vent means between the two seal ring means.

Description:
BACKGROUND OF THE INVENTION

The present invention relates to a safety and alarm device for monitoring the supply of gas to a consumer, particularly in an anaesthetic apparatus which has a main gas circuit, particularly for oxygen, and a secondary gas circuit, particularly for protoxide of nitrogen. Such devices consist of combined safety means for cutting of the secondary gas in the event of an interruption in the supply of the main gas.

Safety devices of this kind already known have given very good results and prove extremely important. The fact is that a certain number of accidents during anaesthetic are due to lack of the supply of oxygen in the anaesthetic apparatus, the patient no longer receiving any ventilation except with an anaesthetic gas. These devices simultaneously cut off the main gas, mainly oxygen, and the secondary gas, usually nitrogen protoxide, which are nearly always associated with one another in anaesthetic operations, as soon as an interruption takes place in the supply of the main gas.

Such devices suffer from the serious drawback of depriving the patient of any ventilation, without warning the specialists of the fault which has occurred.

A general object of the present invention is to provide a safety and alarm device which, at the same time as it cuts off the supply of gas, simultaneously issues an alarm by the same means.

A further object of the present invention is to use the pressure of the secondary gas as a source of energy. The quantity thus consumed is easily reduced to the necessary minimum by the operation of a whistle alarm installed in an appropriate manner.

SUMMARY OF THE INVENTION

According to the present invention there is provided device for monitoring the supply of gas to a patient through main and secondary gas circuits, comprising safety and alarm means by which the supply of secondary gas to the patient is cut off and an alarm operated by secondary gas when the pressure of the main gas supply falls below a predetermined minimum value presenting a danger to the patient. The safety and alarm means comprises a double-part poppet valve which, under normal operating conditions when said main gas pressure is above said predetermined minimum value, obstructs an orifice of a first seat thereby preventing the passage of the secondary gas to an alarm, and means overcoming the pressure of the main gas when it falls below said predetermined minimum value, in order to release the poppet valve from the first seat and cause it to bear against a second seat thereby preventing passage of the secondary gas to the patient and allowing said secondary gas to operate the alarm.

BRIEF DESCRIPTION OF THE DRAWING

An embodiment of the invention will now be described by way of example, with reference to the accompanying drawing which shows an axial section through a safety and alarm device according to the invention, in the alarm position.

DESCRIPTION OF PREFERRED EMBODIMENT

A device according to the present invention is installed between the feed or supply sources of each of two gases, usually oxygen and protoxide of nitrogen, on the one hand, and the patient or consumer, on the other hand, by means of conduits leading to the respective inlets. The device is connected to one of these sources and the patient via a main gas inlet 1 and a main gas outlet 2, particularly for the circulation of oxygen. It is connected to the other source and the patient by a secondary gas inlet 3 and a secondary gas outlet 4, particularly for the circulation of nitrogen protoxide.

The device consists of a cylindrical body 5 inside which moves a stepped piston 6 provided with two annular seals 7 and 8 borne respectively by portions of small diameter 6a and large diameter 6b each sliding respectively in portions of the body 5 of generally the same internal diameter as the external diameter of the portions 6a, 6b. The portion 6a of the piston 6 is prolonged in the form of a rod 9 integral at its end with a double-acting poppet valve 10. This latter can engage in a hermetic manner either on a seat 11 or on a seat 12 at the two ends, front and rear end respectively, of its travel.

The seals 7 and 8 and the seat 11 subdivide the body 5 of the device into four hermetic chambers: a front chamber 13, in which slides the part 6b of large diameter of the piston 6, a middle front chamber 14, a middle rear chamber 15 and a rear chamber 16. This latter is in communication, via the orifice of the seat 12 and a conduit 17, with a whistle 18. The front middle chamber 14 is provided with an outlet 19 leading into the atmosphere.

In the front middle chamber 14 is accommodated a restoring spring 20 which thrusts the piston 6 towards the front end 21 of the device.

The device operates as follows:

The main gas supply, usually oxygen, enters the apparatus through the main gas entry 1 and moves to the consuming appliance, for example an anaesthetic apparatus, through the main gas outlet 2. The pressure of the main gas in the front chamber 12 then thrusts the piston 6 towards the rear, in opposition to the bias of the spring 20. The rod 9, integral with the piston 6, presses the valve 10 onto its seat 12 and closes its orifice. The secondary gas, usually nitrogen protoxide, enters the device through the secondary gas entry 3, penetrates into the rear chamber 16, passes through the open orifice of the seat 11 into the middle rear chamber 15 and thence, via the secondary gas outlet 4, reaches the consuming appliance, for example the anaesthetic apparatus. The communication between the middle rear chamber 15 and the middle front chamber 14 is closed by the seal 7. The two gases thus cannot mix together. The route towards the whistle 18 is closed by the valve 10 pressed against the seat 12.

If the supply of main gas is cut off, the spring 20 moves the piston 6 back towards the front end 21 of the device. The valve 10 also moves towards the front end and bears on the seat 11, closing the passage of the secondary gas towards the rear middle chamber 15 and the consuming appliance. This position of the piston 6 is that shown in the drawing. The supply of secondary gas to the consuming appliance is thus cut off at the same time as the supply of main gas. The valve 10 having then been displaced towards the front end of the device and having left the seat 12, the inlet orifice of the conduit 17 and the path for the secondary gas between the rear chamber 16 and the whistle 18 are open, while the opposite orifice or port, in seat 11, is closed. The valve 10 may close either port with a "clack." When the port of conduit 17 is open, secondary or auxiliary gas from inlet 3 escapes to the atmosphere through whistle 18. The whistle 18 is thus fed at a rate of delivery which is economical but which suffices to give the alarm regarding to the lack of supply to the consuming appliance, particularly for the purpose of indicating that the patient is no longer receiving the required ventilation.

It is obvious that the device according to the present invention is applicable to all cases in which a part is played by a supply of main gas and a secondary supply. Cases in which the apparatus is fed with oxygen as the main gas and with nitrogen protoxide as the secondary gas have been mentioned merely by way of a preferred example, but without any limitative effect. The device according to the present invention can also be constructed in various alternative ways within the scope of the appended claims.