Abstract:
The invention relates to devices and methods for adapting a standard protective mask test apparatus to perform leak testing of a mask air hose assembly as an independent equipment component, i.e., independent of the mask-hose system.

Description:
GOVERNMENT INTEREST 
   The invention described herein may be manufactured, licensed, and used by or for the U.S. Government. 

   TECHNICAL FIELD 
   The present invention relates generally to leak testing of mask air hose assemblies, and more particularly to devices and methods for adapting a standard mask testing apparatus to perform leak testing of mask air hose assemblies independently of the mask systems to which they may be attached. 
   BACKGROUND 
   A number of protective masks are equipped with air hose assemblies to enable the mask to be attached to a separable filter canister, an external air supply, or a portable air purification system. For example the M40A1/M42A1 Joint Forces CB protective masks include standard North American Treaty Organization (NATO) threaded fittings on one or both sides of the mask to enable the wearer to attach a hose assembly or mount a NATO compatible canister, as needed. The Joint Service Mask Leakage Tester (JSMLT) is a portable device used to test the serviceability and proper fit of chemical and biological (CB) protective masks. The JSMLT is designed to test a large number of masks for leaks to a very high degree of certainty as rapidly and reliably as possible. Because such testing frequently may be conducted in the field by operators under duress and/or having limited experience with the test equipment it is important that leak testing devices and procedures be as simple and as reliable as possible. While the JSMLT and similar protective mask test devices are able to perform a number of tests on a variety of different mask systems, such mask test devices lack the capability to test removable air hose assemblies as independent equipment components. Instead, air hose assemblies must be tested by a “mask-hose system” test in which the hose remains attached to the mask. Testing the hose as part of the “mask-hose system” makes it difficult to isolate air hose faults as a source of a leak. These test deficiencies may result in premature disposal of mask systems, decreased confidence in test procedures and decreased confidence in protective mask systems. Such unreliable testing also invariably increases the risk that defective air hose assemblies may be returned to service. 
   SUMMARY 
   In general, in one aspect, an embodiment of a device for testing an air hose assembly for a chemical/biological mask includes an adapter for testing a hose with a mask test apparatus as an independent component part. The adapter provides a first end with an opening and a second end with an opening. The first end has a threaded receptacle to accept a standard male NATO threaded hose coupling and the second end provides a stem that extends outwardly from the receptacle and is dimensioned for insertion and substantially airtight coupling into a headform pneumatic test port of the mask test apparatus. The stem of the hose test adapter preferably extends angularly from the axis of rotation of the receptacle at an angle of approximately 45 degrees. In another aspect, the body of the hose test adapter is of unitary construction and may be formed by an injection molding process from Zytel 77G33L or similar. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view the preferred embodiment of a hose test adapter according to the present invention. 
       FIG. 2  shows a side sectional view of the hose test adapter of  FIG. 1 . 
       FIG. 3  is a diagram of a Joint Service Mask Tester equipped with the hose test adapter of  FIG. 1  and configured for testing of a standard NATO threaded chemical-biological mask hose as an independent component part. 
   

   DETAILED DESCRIPTION 
   In the following detailed description, reference is made to the accompanying drawings. The drawings forms a part of this invention disclosure and show, by way of illustration, specific embodiments in which the invention, as claimed, may be practiced. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. As will be appreciated by those of skill in the art, the present invention may be embodied in methods and devices. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
   Embodiments of hose test adapters according to the present invention are designed for use in connection with protective mask leak test apparatus such as the Joint Forces TDA-99M or TDA-99B, or similar. A simplified schematic of a portable protective mask leakage test apparatus  200  is shown in  FIG. 3 . Mask test apparatus  200  provides leak and serviceability testing of a variety of sizes and types of negative pressure Chemical, Biological and Radiological protective masks without requiring an operator to actually don the mask. Leak testing of a mask essentially involves removing the gas canister from the mask, plugging the mask canister port and outlet valve, and affixing the mask by its own harness to points of attachment on test apparatus  200  so that it fits snugly over a face-shaped headform  204 . An inflatable bladder  208  of headform  204  engages the faceseal on the mask and simulates the seal characteristics of the face of a user. If the mask is equipped with an air hose, the canister is removed from the hose end and the hose end is attached to a hose test port  212  on the test apparatus  200  via a threaded adapter  214 . After the mask has been thusly secured, a slight vacuum is applied through headform  204  to the interior of the mask. Test apparatus  200  then monitors for leaks in the mask and any attached hose while the operator performs a number of test challenges. However, since the entire mask-hose system must be tested, isolating faults or leaks in the air hose assembly is very difficult. 
   Mask test apparatus  200  is equipped with two headforms  204  to accommodate masks of different sizes. The headforms  204  are push-fit mounted to a headform mounting pedestal  202  on test apparatus  200 . Pedestal  202  and headform  204  are joined at an interface that includes four push-fit o-ring sealed pressure couplings (not shown). One such pressure coupling communicates a source of negative air pressure to a head test port  210  in the top of headform  204 . Mask test apparatus  200  delivers negative air pressure to the mask under test through head test port  210  while the mask is probed for leaks. 
     FIG. 1  shows a side sectional view of a preferred exemplary embodiment of an air hose test adapter (hose test adapter)  100  according to the present invention. Hose test adapter  100  is configured to adapt a standard NATO threaded male pneumatic fitting used for attachment of a NATO threaded mask end fitting  152  of flexible air hose  150  into head test port  210  of mask test apparatus  200 . Hose test adapter  100  comprises a body having a first end  102  with a first opening  104  and a second end  106  with a second opening  108  and a passage  107  between the first opening  104  and second opening  108  to enable air to flow through. First end  102  provides a cap shaped NATO threaded receptacle  110  that engages a standard male NATO threaded air hose coupling. An annular seal  118  such as a standard M-45 canister/air hose gasket is disposed in threaded receptacle  110  to prevent leakage of air. The outside surface of receptacle  110  preferably has a knurled surface  111  to aid in gripping hose test adapter  100 . 
   Second end  106  of hose test adapter  100  provides a tubular stem  112  that extends outwardly from the back of receptacle  110  and terminates at a tip  113  that is preferably chamfered to facilitate insertion of stem  112  into head test port  210 . The external diameter of stem  112  is preferably 0.710 inches, dimensioned for snug push-fit coupling into head test port  210 . The internal diameter of stem  112  is at least 0.325 inches throughout to provide unrestricted air flow through the hose to be tested. A pair of o-rings seals  114 , or similar circumferential pneumatic seals, are disposed in 0.12 inch radial grooves  115  near tip  113 . The first groove is located 0.15 inches from tip  113  and the second 0.55 from tip  113 . While a single o-ring seal may be employed, dual o-ring seals  114  provide an added measure of assurance that air will not leak from head test port  210 . A radial flange  116  approximately 0.25 inch thick and 0.975 inch in diameter is positioned 0.710 inch from tip  113  to prevent over-insertion of stem  112  into head test port  210 . Stem  112  extends from the axis of rotation of receptacle  110  at an angle of approximately 45 degrees so that air hose  150  is oriented at approximately the same angle as when it is attached to a mask. 
   The body of hose test adapter  100  is of unitary construction and preferably formed by an injection molding process from Zytel 77G33L or similar hard plastic material. 
   Operation of a preferred embodiment according to the present invention is substantially as follows. Headform  204  is mounted to mask test apparatus  200 . Chamfered end  113  of stem  112  of hose test adapter  100  is inserted into head test port  210  of headform  204 . Male NATO threaded mask end fitting  152  of air hose assembly  150  is threaded securely into receptacle  110  of hose test adapter  100 . The canister end fitting  154  of air hose assembly  150  is connected via threaded adapter  214  into hose test port  212 . As in a mask test, a predetermined negative air pressure is delivered by mask test apparatus  200  to bead test port  210 . Test apparatus  200  then monitors for leaks in air hose assembly  150  while the operator performs a number of test challenges. 
   CONCLUSION 
   As has been shown, embodiments according to the present invention provide effective and efficient systems, methods and devices for adapting a standard mask testing apparatus to perform leak testing of mask air hose assemblies independently of the mask systems to which they may be attached. Embodiments according to the present invention simplify detection and isolation of mask air hose assembly leaks and increase confidence in test procedures and in protective mask systems generally. Various modifications to the described embodiments may be made without departing from the spirit and scope of the claimed invention. Accordingly, other embodiments are within the scope of the invention, which is limited only by the following claims.