the apparatus 1 according to the invention is shown in fig1 . the apparatus 1 comprises a housing 2 in which a chamber for receiving gas is delimited ( see fig2 ). the housing 2 is provided with a gas line 3 , which can be connected to a source ( not shown ) for supplying gas to the housing 2 . the apparatus 1 further comprises a balloon 4 . this balloon 4 can be compressed by hand ( in the direction of the arrows shown in the figure ) to pressurise gas that has been received in the housing 2 . gas can be discharged from the housing 2 via the breathing tube 5 . in use , this breathing tube 5 is fed to a patient who has to be ventilated with the aid of the apparatus 1 . when a patient exhales gas this gas is fed back to the housing 2 via the breathing tube 5 . as a result of the presence of discharge channels ( explained with reference to fig2 et seq . ), exhaled gas is fed via a discharge channel 26 to a discharge 6 , which discharges said exhaled gas from the apparatus 1 . furthermore , the apparatus is provided with an adjusting knob 7 , with the aid of which a pretensioning force can be set on a safety valve 30 . the apparatus further comprises a dial 8 , with the aid of which the pressure which a patient must overcome to be able to exhale gas via the apparatus is set . the functioning of the adjusting knob 7 and the dial 8 is explained in detail with reference to fig2 . fig2 shows a cross - section of the apparatus according to fig1 . a chamber 9 , in which a quantity of gas to be administered can be received , is delimited in the housing 2 . the chamber 9 is in open communication with the balloon 4 ( not shown ) via a line 10 . via the line 10 gas can be forced from the balloon 4 under elevated pressure into the chamber 9 . the chamber 9 is provided at the bottom thereof with a movably mounted wall 11 . the wall 11 is movable between two extreme positions which are shown in fig3 and 4 , respectively . the inlet 16 of the breathing tube 5 is located underneath the movable wall 11 . the inlet 16 is separated from the chamber 9 by the wall 11 . a discharge channel 26 , for discharging exhaled air in the direction of the discharge 6 , is also located underneath the movable wall 11 . one or more channels 15 have been made in the movable wall 11 itself , which channels can be shut off by means of a shut - off element 12 . when building up gas pressure in the chamber 9 the movable wall 11 is forced , with the aid of the spring 17 , against the inlet 16 of the breathing tube 5 . in this position the communication between the breathing tube 5 and the discharge channel 26 is shut off . when the pressure in the chamber is then raised the shut - off element 12 will move down . as a result the channels 15 in the movable wall 11 are exposed , so that gas transport can take place from the chamber 9 in the direction of the breathing tube 5 . this position is shown in fig3 . it can be seen in fig3 that the wall 11 is in contact with the inlet 16 of the breathing tube 5 . the shut - off element 12 has moved down and the shut - off element 12 is held in the position shown because a ridge 14 is in contact with a projecting section of the wall 11 . in the position shown the shut - off face 13 of the shut - off element 12 is free from the channels 15 in the wall 11 . consequently fluid transport can take place through the wall 11 in the direction of the breathing tube 5 . opening of the channels 15 can be promoted by making the shut - off face 13 of the shut - off element 12 of a relatively flexible material , such as rubber . in this case the outermost edges of the shut - off face 13 are able to bend , so that the channels are exposed to a considerable extent . since the movable wall 11 is in contact with the inlet 16 of the breathing tube 5 , the open connection between the breathing tube 5 and the discharge channel 26 is shut off . as a result air from chamber 9 is prevented from passing into the discharge channel 26 . the shut - off element 12 is connected to a spring 27 . with the aid of this spring the movable wall 11 can be placed under a certain pretension . the shut - off element 12 exposes the channels 15 in the movable wall 11 only at a point in time when a specific threshold value is exceeded . fig4 shows the case where the movable wall 11 has moved into the second position thereof . the movable wall 11 can assume this position when the pressure in the breathing tube becomes higher than that in the chamber 9 . this position is assumed when the patient exhales . a patient cannot get the wall 11 into the position shown in fig4 simply by exhaling . in order to be able to move the wall into this position a certain threshold value must be exceeded , which is determined by the pretensioning force that is exerted on the wall 11 by means of the difference between springs 17 - 27 . the higher the pretensioning force of the spring 17 on the wall 11 , the higher must be the pressure in the breathing tube in order to be able to move the wall into the position shown . it can be seen from fig4 that in the position shown there is a free passage between the outlet end 16 of the breathing tube 5 and the discharge channel 26 . this means that the patient can blow out the exhaled air via the breathing tube 5 and the discharge channel 26 connected thereto in the direction of the discharge 6 of the apparatus ( see fig2 ). it can also be seen in fig2 that the shut - off element 12 shuts off the channels 15 in the movable wall 11 . this means that the exhaled air cannot pass into the chamber 9 . the shut - off face 13 of the shut - off element 12 is in contact with the openings of the channels 15 and so prevents fluid transport from the breathing tube 5 in the direction of the chamber 9 . the extreme position of the movable wall 11 is delimited by ridges 25 which project from the wall of the chamber 9 . the function of the spring 17 is described with reference to fig3 and 4 . it can be seen in fig2 that the pretensioning force on the spring 17 is adjustable with the aid of a dial 8 . this dial can be turned by hand , so that a stop face 18 , against which the end of the spring 17 bears , can be moved relative to the wall 11 . depending on the desired objective and depending on the expiration force ( pressure that can be built up by a patient ) of a patient , a certain pretension can be applied to the spring 17 . because the pretensioning force on the spring 17 is adjustable by hand , the apparatus 1 according to the invention is easy to use . a correct setting can , for example , be guaranteed by providing a scale on the apparatus and / or on the dial 8 . it can also be seen in fig2 that the top wall of the chamber 9 comprises a hollow body 19 . this hollow body 19 is closed off at the top by means of a valve 30 . this valve 30 serves as a safety valve . if the pressure in the chamber 9 becomes too high the safety valve 30 is forced upwards so that free communication is produced between the chamber 9 and openings 21 - 22 which have been made in the rotary body that is connected to the dial 8 . the air can escape from the chamber 9 via these openings 22 and be fed to the discharge 6 . this prevents gas under too high a pressure being supplied to a patient via the breathing tube 5 . the maximum pressure that can be reached in the chamber 9 can be set by adjusting the pretension on the valve 30 . this pretension is achieved with the aid of a spring 20 . the pretension of the spring 20 can be adjusted by means of a rotary knob 7 . this knob 7 can also be operated by hand . a further embodiment of the ventilator according to the invention is shown in fig5 . according to fig5 a hose 40 is arranged between the housing 2 and the balloon 4 . as a result of the presence of the hose 40 , a user is able to exert manual force on the balloon 4 whilst the balloon 4 is some distance away from the housing 2 . this increases the ease of use of the apparatus according to the invention . medical staff can , for example , operate the balloon 4 from the side of the patient &# 39 ; s bed . according to fig5 the gas line 3 is located at the end of the hose 40 , that is to say some distance away from the housing 2 . this too offers the option of coupling the gas supply to the apparatus according to the invention some distance away from the patient &# 39 ; s mouth . the gas supply will usually have to be coupled to the gas line 3 from anaesthesia equipment or an anaesthesia wall set . fig5 furthermore shows the case where the hose 40 has an inner line 41 which connects the balloon 4 to the housing 2 . the line 41 is used to supply fresh gas in the direction of the housing . the line 41 is enclosed by a second line 42 . this line 42 is used as discharge line . the line 42 terminates in a discharge opening 43 . as a result of the coaxial construction of the supply line for the gas and the discharge line for the gas , only one hose has to be fed from equipment in the direction of the patient . this application further increases the ease of use of the apparatus according to the invention . instead of the balloon shown in fig1 and 5 , use can also be made of the so - called “ rigid balloon ”. a rigid balloon is a balloon which is provided with a valve . after the force for squeezing the balloon is removed , the balloon will assume its original shape again . during this movement the valve in the rigid balloon will be opened to draw in a quantity of fresh gas ( ambient air ). for the sake of clarity it is pointed out that the apparatus shown in the figures can be produced in various sizes . for instance , a system can be made with smaller dimensions which is especially suitable for children or neonates . in this case the lines will also be made smaller . with the aid of the adjustable force on the safety valve 30 it is possible to set a maximum pressure in the chamber 9 of , for example , 20 - 60 cm h 2 o . the maximum pressure which a patient must overcome in order to be able to blow air out of the apparatus 1 can be set , for example , from 0 to 20 cm h 2 o . in order to make the apparatus according to the invention also suitable for children , the aim is to keep the dead volume in the apparatus as small as possible . by means of the construction as is shown in fig1 to 4 it is possible to achieve a dead volume of typically at most 7 ml . the connection of the balloon to the apparatus 1 via the line 10 can , for example , be made using a so - called balloon cone with an external diameter of 22 mm . the discharge 6 can be constructed as an evacuation cone of 19 mm . the breathing tube 5 can be constructed as a cone of 22 / 15 mm . the apparatus according to the invention is provided with a self - closing 24 measurement channel 23 which connects to the breathing tube 5 . a pressure gauge can be fitted in this measurement channel in order to be able to measure the instantaneous pressure in the breathing tube 5 . the pressure gauge can be constructed as a manometer or as an electronic measuring device . furthermore , it is possible to fill the chamber 9 with the aid of a pump , for example a time - controlled pump , instead of a balloon . in this way a constant flow from the chamber to the breathing tube can be guaranteed while a patient is inhaling . the movable wall 11 can be made of various types of materials . as an alternative , the moveable wall can also be constructed as a flexible plate clamped in place . in this case the moveable wall forms a membrane that is movable to and fro .
an apparatus for administering a gas to a person or an animal , is provided with a chamber for receiving a quantity of gas to be administered . the chamber is provided with a gas line for supplying gas from a source to the chamber and elements for pressurizing the gas in the chamber . the chamber is connected to a breathing tube for supplying pressurized gas from the chamber to the person or the animal , wherein the breathing tube connects to a discharge channel , for discharging gas exhaled by the person or the animal , via a valve , which restricts the flow of exhaled gas from the breathing tube to the discharge channel in order to build up gas pressure in the breathing tube during exhalation .