![]() Unfortunately, it's unknown what filter belongs with this mask, but filters commonly sold with the mask typically feature markings of BICAPA, so it is likely that the BICAPA filters were the original or similar filter. The end result is a comfortable and secure peripheral seal.Ī chin strap is stitched into the fabric that forms the peripheral seal, to ensure the wearers chin is inserted correctly and comfortably. External overhang was fixed into place with some kind of glue adhesive and more stitching. To secure this fabric into place internally, stitching were used. A black rubber gasket inside ensures a good seal.ĭuring the masks construction, a grey/brown felt fabric was stretched over the masks peripheral seal (which at this point was just plain rubber) and subsequently folded into the rubber. This was done so that the filter can only be inserted correctly. The Typ 4 intake valve assembly has 2 parallel notches cut out of the threading. BICAPA STOCKHOLM' a date of manufacture should also feature on this housing. The metal housing is stamped: 'BIRGER CARLSON & Co. The exhale valve assembly consists of the valve itself and its protective housing made of metal. The entire exhale valve assembly can be removed by unthreading it. This assembly is affixed to the mask with a metal clamp. The Typ 4 valves are housed inside of a pear shaped steel valve assembly. The tabs themselves are stitched into the mask and a layer of adhesive is also applied to the tab. ![]() The end of each strap is stitched to a fabric tab projecting from the mask. The straps are affixed in a very secure manner. It clips into a hook assembly on the other side to create a neck-strap. These straps do not feature any kind of adjustment buckle, instead one buckle can be found further down the assembly which pulls the 3 top straps downwards to tighten them.Ī final strap featuring a D-ring can be found at the bottom. For comfort and overall ease-of-use, the Typ 4 straps are made from elastic covered in fabric similar to that covering the masks front. The Typ 4 utilised a 5-point head-harness, not too dissimilar in construction from other masks from this era. These plastic lens films have a tendency to turn slightly yellow with age - suggesting that the film might be made of cellulose. It is generally not recommended to do so the tabs are incredibly fragile and often snap off at the slightest pressure. ![]() The coils can be removed by a small metal tab that sticks slightly out. It was most likely put in to ensure the plastic lens film does not move around or unstick itself. Internally, there is a coil that spans the entire circumference of the lenses. Each lens is about 8.5mm with 6.5mm glass. The lenses had at least two layers, glass on the outside, with plastic film on the inside (to prevent fogging from exhaled breath). The actual lenses themselves are held in place by more metal rings that appear to have been crimped into the facepiece. These outer rings have a knurling texture on them. The outermost ring, fashioned from grey metal held the rest of the eyepiece assembly together. The wearers vision was provided by 2 well-constructed eyepiece assemblies. This was a common design feature intended to protect rubber components underneath. From 1969-1993 Forsheda manufactured more than 3,000,000 gas masks for the Swedish Rescue Services In the mid 1990s Forsheda signed a contract to supply the latest NBC gas mask to the Swedish Armed Forces.Akin to most masks of this era, the Typ 4 facepiece is made from canvas-coated rubber. Recognizing the need for a world class civilian gas mask, the A4 was developed and put into production.Features of the A4 Mask: Superior penetration protection from all threat agents, tested and verified to work for more than 24 hours in a contaminated area Large, specially ground lenses provide up to 88% normal field of vision Filter thread matches NATO's STANAG 4155 (40mm) Comfortable 6 strap harness ensures a perfect fit Weighs under 1 pound Airflow is optimized across both lenses to prevent fogging Made from latest technology and materials The Forsheda NBC Record: Supplier of protection equipment to the Swedish Army since 1960 Manufactured M51 gas masks under direct license from the US Government Sweden is one of two countries who supplies their entire population with NBC protective equipment, with Forsheda being the #1 manufacturer. he Forsheda A4 Gas Mask is a response to a post 9/11 world. The Forsheda A4 Gas Mask is a premium NBC rated gas mask that has never been issued to soldiers and has been in storage for the past 5 years. ![]() The F2 has been in service by the Swedish Armed Forces and Swedish Rescue Services since 1997 with more than 1,000,000 masks having been produced. The Forsheda A4 was developed as the civilian version of the Swedish military NBC gas mask F2. ![]()
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