Patent Abstract:
A personal protective suit including a sealed shell equipped with connection device intended to be connected to one same pressurized air source, air distribution device having an air intake connected to the connection device, and at least one first and one second air outlet, respectively intended to supply device for delivering air to the wearer and device for ventilating the suit, wherein the air distribution device includes a valve designed to reduce the air flow rate of the second air outlet when the air pressure at the air intake is below a determined value, while maintaining the supply of air to the wearer.

Full Description:
TECHNICAL FIELD 
     The invention concerns a personal protective suit and a corresponding protective ensemble. 
     BACKGROUND 
     Protective ensembles are used in the field of civilian safety or in industry, for example in the nuclear or chemical industry to insulate a person from a hostile outside environment. 
     In the nuclear industry, persons are led to ensuring the maintenance of equipment or to conducting tasks in contaminated environments, contaminated in particular by radioactive particles. Under these conditions, such persons must be encapsulated in a protective suit to avoid any contact between the skin and radioactive particles and they must not breathe in any outside contaminated air. 
     Having regard to the long duration and complexity of some operations carried out by such persons, it is important that the wearing of this suit should be ergonomic and comfortable. In addition, it must be possible for the donning and fitting of the suit as well as the removal thereof to be performed simply and relatively quickly. 
     A protective ensemble is known from document FR 2 793 147. It comprises a sealed suit fed with air to allow ventilation and therefore the lowering of the temperature inside the suit. This provides increased comfort for the wearer in particular in the event of prolonged used of the protective garment. 
     Also, air is fed via a flexible air intake to a mask held to the wearer&#39;s face by means of supporting straps. 
     Another protective ensemble is described in document US 2004/0226558. It is in the form of a suit comprising in particular a part that forms a hood and means for connection to a source of compressed air. The compressed air is guided firstly into the inner volume of the hood and secondly into the other parts of the suit to ensure the ventilation thereof. 
     The wearer is therefore not obliged to wear a mask since it is possible directly to breathe the air contained in the hood. The air flow rate is adjusted so that there is sufficient air renewal to avoid a substantial increase in carbon dioxide within the hood. 
     In addition, only one air feed can be used, which allows simplification of the use of the said protective system. 
     In this case however, should there be pressure be drop in the air supply network, this will give rise to risks for the wearer being ill-supplied with air. There may a sudden increase in the carbon dioxide level inside the hood volume which, within a few instants, may exceed a critical threshold placing the wearer in danger. 
     BRIEF SUMMARY 
     The invention sets out to remedy this shortcoming by proposing a suit and corresponding protective ensemble which can offset a pressure drop within the air supply network. 
     For this purpose, the invention concerns a personal protective suit comprising a sealed outer shell equipped with connection means intended to be connected to one same pressurized air source, means for distributing air having an air intake connected to the connection means, and at least one first and one second air outlet respectively intended to supply means for delivering breathable air to the wearer and means for ventilating the suit, characterized in that the air distribution means comprise a valve reacting to air pressure at the air intake to reduce the air flow rate of the second air outlet towards the suit when the air pressure at the air intake is below a determined value, whilst maintaining the supply of breathable air to the wearer. 
     The means for delivering air to the wearer are therefore given feed priority. The air derived from the supply network is therefore no longer or only little used to ventilate the suit. It is recalled that the said ventilation is solely intended to ensure wearer comfort. The vital function of supplying air to the wearer at a substantially constant flow rate is therefore preserved to the detriment of comfort. 
     According to one characteristic of the invention, the valve is designed such that the air flow rate in the second air outlet decreases progressively with the air pressure at the air intake. 
     If the pressure drop in the supply network is small, it is not necessary to stop ventilation completely. In this case, only part of the air intended to ensure ventilation is diverted to the benefit of the breathable air supply to the wearer. 
     Advantageously, the valve comprises a shutter which, cooperating with a return spring, is designed to shut off the second air outlet in full or in part, in relation to the air pressure at the air intake. 
     According to one possibility of the invention, the air distribution means comprise a body in which are arranged a first channel forming the air intake, a second channel connected to the first channel and forming the first air outlet, and a third channel forming the second air outlet and leading into the first channel at a calibrated opening, the shutter and the return spring being arranged such that the shutter is applied against the calibrated opening if there is no air pressure in the first channel, the shutter being gradually moved away from the opening when the air pressure in the first channel exceeds a predetermined value. 
     Advantageously, the channels connected to the air outlets for the supply of air to the wearer and for ventilation of the suit are equipped with air flow rate regulators. 
     The flow regulators allow a flow rate to be obtained whose value varies little in the event of variation in the supply pressure. Should there be no regulation, the air passage orifices inside the distributor would need to be calibrated differently in relation to the supply pressure. Therefore, with a distributor designed to operate with a pressure of the order of 5.5 to 6.5 bars, any use with a pressure of 9 or 10 bars would translate as a delivered air flow rate that is too high, generating overpressure within the suit which may cause bursting thereof. With flow rate regulators in the channels it is possible to use the same distributor over a wide range of supply pressures. 
     According to one embodiment of this distributor, each flow rate regulator comprises a piston which, housed in a channel, is subjected to the action of a spring to modify the cross-section of the air throughway in relation to pressure. 
     Advantageously, the air distributor is mounted outside the suit and also acts as tap. 
     The invention further concerns a personal protective ensemble comprising means for delivering air to the wearer, equipped with an air supply line, characterized in that it comprises a protective suit according to the invention, the air supply line being connected to the first air outlet of the distribution means. 
     Preferably the air supply line comprises a first and a second air intake, the first air intake being connected to the first air outlet of the distribution means in normal position of use, the second air intake of the air supply line being intended to be connected to a secondary source of compressed air. 
     Therefore, when removing the protective ensemble, the wearer connects the second air intake to the source of compressed air and then disconnects the first air intake from the suit. The suit can then be removed whilst continuing to supply air to the wearer. 
     According to one characteristic of the invention, the means for delivering air to the wearer comprise a mask or hood delimiting an inner volume fed with air. 
     Advantageously, the suit comprises a release valve arranged to allow release of air contained in the suit towards the outside, when this air exceeds a determined pressure. 
     According to one embodiment of the invention, the suit comprises a removable band which, after removal, is capable of releasing an opening intended to facilitate stepping out of the suit. 
     Preferably the suit is equipped with at least one ventilation duct connected to the second outlet of the distribution means, designed to direct part of the pressurized air into the inner volume of the suit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       At all events, the invention will be well understood aided by the following description with reference to the appended schematic drawing which, as an example illustrates one embodiment of this protective device and of this corresponding ensemble. 
         FIG. 1  is a front view of the suit; 
         FIGS. 2 and 3  are views illustrating the successive steps for removing the protective ensemble; 
         FIG. 4  is a view corresponding to  FIG. 1 , illustrating one variant of embodiment of the invention; 
         FIG. 5  is a longitudinal section view of the air distribution means; 
         FIG. 6  is a side view; 
         FIG. 7  is a diagram showing the flow of the air supply network, the flow of the ventilation means and the flow of the air feed means to the user, in relation to the pressure of the air supply network; 
         FIG. 8  illustrates a variant of the distributor in  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION 
     As illustrated in  FIG. 1 , a protective ensemble according to the invention comprises an outer suit  1  made in a flexible, armoured material sealed against radioactive particles, for example in polyvinyl chloride on a polyester backing. The suit covers all the parts of the body and in particular it comprises a part enclosing the head, forming a helmet  2  equipped with a transparent visor  3 . 
     The suit comprises gloves  4  and areas  5  intended to receive the wearer&#39;s feet comprising laces  6  arranged opposite the ankle and provided with quick tightening means. The suit  1  also comprises a donning opening extending over the front side of the suit, at the level of the user&#39;s chest. The opening can be closed by means of a zip fastener  7 , a flap  8  being folded over the closure  7 . 
     A removable band  9  extends from the end of one arm to the end of the other arm, the removal of the band  9  allowing full opening of the suit  1  along this area. 
     The front side of the suit is provided with a connector  10  extending outside the suit and intended to be connected to a compressed air supply network  11 . A release valve  12  is arranged in the back part of the helmet  2  allowing the release of air contained inside the suit  1  towards the outside when the pressure of this air exceeds a determined value. 
     The suit  1  is also equipped with air distribution means  13  having a first and a second outlet branch  14 ,  15 . These branches are housed in the suit  1 . The second branch  15  is connected to an inlet of a filter  16  of HEPA  19  type (High Efficiency Particulate Air Filter or             High Efficiency Particulate Absorbing Filter), housed in the suit  1  and capable in one pass of filtering at least 99.97% of particles having a diameter equal to or more than 0.3 μm.
     The structure of the air distribution means  13  is more particularly illustrated in  FIGS. 5 and 6 . They comprise a body  17  in which there are arranged a first channel  18  forming the air intake, a second channel  19  connected to the first channel  18  extending perpendicular thereto, and formed in the first air outlet branch  14 , and a third channel  20  formed in the second air outlet branch  15  and opening into the first channel  18  at a calibrated opening  21 . The third channel  20  extends along axis A of the first channel  18  and has a chamber  22  of larger diameter into which the first channel  18  opens. A tubular support  23  is fixed inside the chamber, the support comprising a first end facing the side of the calibrated opening  21  and a second end  24  facing the free end of the third channel  20 . 
     The second end  24  of the support  23  is tapped and cooperates with a screw  25  forming an abutment. 
     A shutter  26  is slidingly mounted within the tubular support  23 , a counter-weighted return spring  27  also being mounted in the support  23 , between the shutter  26  and the spring  25 . 
     The return spring  27  and the shutter  26  are arranged such that the shutter  26  is applied against the calibrated opening  21  if there is no air pressure in the first channel  18 , the shutter  26  being gradually moved away from the opening  21  when the air pressure inside the first channel  18  exceeds a predetermined value. 
       FIG. 8  illustrates a variant of embodiment of the air distributor in which the same parts are designated by the same reference numbers as previously. It is to be noted that in this figure the shutter  26  is not shown although it is used. 
     In this distributor, the channels  19 ,  20  connected to the two outlets for supplying air to the wearer and for ventilating the suit, are equipped with airflow regulators respectively formed of pistons  39  and  40  subjected on one side to air pressure and on the opposite side to the antagonist action of a counter-weighted spring  42 ,  43  to ensure a flow rate within a determined range in each outlet conduit. 
     For example, when the inlet pressure is between 3 and 8 bars, the overall outlet flow rate is between 500 and 800 liters per minute and the distribution, via adapted counter-weighting of the springs  42  and  43 , is 170 to 260 liters per minute for breathable air and 330 to 540 liters per minute for the air to ventilate the suit. 
     The outlet of the filter  16  feeds several ventilation channels  28  formed in the suit  1 . These direct the air derived from the filter  16  towards the heat-accumulating regions  29  such as those arranged in the vicinity of the wearer&#39;s armpits, knees and groin. 
     The first branch  14  is connected to a nozzle  30  providing air to the hood  31 , via a HEPA filter  32  and an air supply line  33 . 
     This line comprises one fork-shaped end having a first and a second branch  34 ,  35  each provided with a connector. 
     The hood  31  has a front visor  36  and a back part equipped with a release valve (not visible) arranged to allow release of the air contained in the hood  31  towards the outside when it exceeds a determined pressure value. 
     The inner volume of the hood  31  is delimited by a neckband  37  made in a flexible, elastic material having a central opening allowing insertion of the wearer&#39;s head. 
     The hood  31  further comprises a removable band (not illustrated) which, after removal, is able to release an opening for access to inside the hood  31 . 
     The hood  31  is mounted on a sheet of fabric  37  for attachment to the wearer. 
     According to another embodiment, illustrated in  FIG. 4 , the supply line  33  is not connected to a hood  31  but to a mask  38  attached via holding straps  39 . 
     The functioning of the invention will now be described in more detail with reference to the embodiment illustrated in  FIGS. 1 to 3 . 
     When putting on the assembly, the user first dons the suit  1  which is fitted by means a belt  40  integrated in the suit  1 , connects the supply line  33  to the connector  10  and connects the first branch  34  of the air supply line  33  to the first branch  14  of the distribution means  13 . The hood  31  is thereby supplied with air via the compressed air network  11 . 
     In parallel the shutter  26 , subjected to the force exerted by the compressed air at the first channel  18 , is moved within the tubular support  23  against the return force exerted by the spring  27 , so that it moves away from the calibrated opening  21 . The passing of air from the first channel  18  to the third channel  20  is then permitted, the ventilation ducts  28  thereby being supplied with air. 
     The user can then slip on the hood  31  and finish installing the remainder of the suit  1 , in particular covering the hood  31  with the helmet  2  then closing the zip fastener  7 . It is pointed out that the user is able to be equipped unassisted. 
     Once closed, the suit  1  is gradually inflated with air derived from the ventilation ducts  28 , this air then being able to escape via the release valve  12  ad/or via leaks which may appear at the zip fastener  7  for example. Therefore, despite slight leaks the user does not run any risk since the air escaping from the suit  1  prevents any entry of particles. 
     The wearer can then proceed with carrying out the tasks to be conducted and is able to move unrestricted to within the extent authorised by the hose  11  of the compressed air supply network. 
     Once the operations are completed, the wearer leaves the contaminated area, possibly passes through a decontamination airlock, and then removes the removable band  9  to open the suit  1 . This suit then rolls up outwardly to avoid any contact between the hands or the remainder of the body with the outer wall of the suit  1  on which radioactive particles may have deposited. 
     The wearer then connects the second branch  35  to a secondary supply network  41  of compressed air and disconnects the first branch  34  from the suit  1 . The suit can then be fully removed, the hood  31  continuing to be supplied by the secondary supply network  41 . 
     It is pointed out that the suit  1  is a disposable suit since in this embodiment no provision is made for possible repositioning of the removable band  9  after removal thereof. 
     In the event of a pressure drop in the air supply network  11 , the air pressure in the first channel  18  is decreased. The force exerted by the counter-weighted spring  27  then tends to move the shutter  26  in the direction of the calibrated opening  21 , the result of which is to reduce the cross-section of the air throughway from the first channel  18  to the third channel  20 . The flow rate of the air feeding the ventilation ducts  28  is thereby reduced. The proportion of air dedicated to feeding the hood  31  is therefore increased. 
     This principle is best illustrated in  FIG. 7 , using the air distribution means shown in  FIG. 5 , which gives a diagram in relation to the air pressure in the first channel  18  of a first curve  42  illustrating the air flow circulating in the first channel  18 , a second curve  43  illustrating the air flow circulating in the second channel  19  and a third curve  44  illustrating the air flow circulating in the third channel  20 . 
     The air flow circulating in the first channel  18  i.e. derived directly from the air supply network  11 , reduces with pressure. In addition, in the event of a pressure drop in the air supply network  11  i.e. in the first channel  18 , the flow dedicated to ventilation is highly limited by movement of the shutter  26  (see curve  44 ). As a result, the air flow dedicated to feeding air to the wearer is scarcely reduced (see curve  43 ). 
     It is therefore noted that in the event of a pressure drop in the air supply network, the invention allows priority to be given to the breathable air supply to the user, to the detriment of the user&#39;s comfort provided by ventilation of the suit. 
     The invention therefore provides a personal protective suit and ensemble that are reliable whilst remaining ergonomic, comfortable and easy to use.

Technology Classification (CPC): 0