GasMasksUK
MkII General Service Respirator
Type: MkII General Service Respirator
Model: N/A
Filter: Type A
Application: Military (Royal Navy)
Despite being one of the most important developments of the era in protection against chemical weapons, the Small Box Respirator of the First World War was designed primarily for land use by the British Army, and thus wasn't suited particularly well for use by the Royal Navy onboard ships. The identified shortcomings were mainly related to the design of the facepiece itself. Due to its loose and baggy construction, the eyepieces were not in a rigid fixed position and were thus prone to movement, especially when placed against optical sights. This coupled with their fairly fragile construction made the Small Box Respirator quite unsuitable for use with optical sights in general. Speech transmission was also very difficult due to the Small Box Respirator having an internal mouthpiece and nose clip as the primary means of protecting the wearers airways apposed to a gas tight face seal.
The Royal Navy Anti Gas School at Devonport held weekly courses, at the end of which the attendees posed for photos with the class number both with and without respirators being worn. These photos were subsequently printed onto postcards and distributed to the attendees meaning that they are fairly easy to find on the collectors market. This particular postcard showing Class No.295 shows the MkII, as well as the MkIV* General Service Respirator.
This lack of a proper gas tight seal and adjustable head harness also raised the concerns that the facepiece may become dislodged from its correctly worn position; a likely scenario whilst moving in the close confines of a ship, thus resulting in the wearer losing a considerable of degree of protection, especially to the eyes. The Small Box Respirator also had quite a short hose, and was designed to be carried on the wearers chest where it would remain easily accessible, this again may have posed an issue for the wearer as it could interfere with both movement around a ship, and when using certain pieces of equipment. A derivative of the Small Box Respirator did exist during this period which instead of the conventional full facepiece was likely worn with separate goggles with the same mouthpiece and a nose clip, similar to that purportedly used by those driving vehicles during the First World War. However, instead of the filter being carried in the chest position, it was slung over the wearers shoulder an secured by two straps which crossed the wearers chest.
In order to address these issues, The Admiralty issued a request in 1919 for a respirator to be be designed specifically for naval use to replace the Small Box Respirator and its derivatives. This request likely lay out specific criteria including; a moulded rubber facepiece through which a gas tight seal can be achieved, a secondary means of providing a gas tight seal, improved speech transmission, eyepieces compatible with optical sights, a means of preventing the eyepieces from fogging, and a means of carrying which won't interfere with activities conducted onboard a ship.
A design for a whole new respirator was developed at Porton Down which addressed these requirements, and a patent applied for by Major John Ambrose Sadd in September 1922. The resulting design was completely unique at the time both in terms of how it was manufactured, and the features of its design itself, some of which only appeared on this design and didn't see subsequent use. The designation of MkII is currently purely speculation at present, with little documentation on this respirator existing despite it being adopted into service with the Royal Navy.
Drawings from the original patent showing the facepiece design with emphasis on the means of preventing the eyepieces from fogging. The design of the head harness on the production model differs from that in the patent in that the adjustment buckles have been moved to the facepiece, and the central pad removed entirely.
Fortunately, a copy of the original patent exists which explains the design in great detail and even the manufacturing methods and tooling which would be required during the moulding process. A key element of the design was the moulded rubber facepiece which in itself is a fairly complex component. As well as being ergonomically moulded to provide a gas tight seal with the wearers face, it also incorporated moulded passages through which inhaled air would be directed over the eyepieces in order to prevent them from fogging. It also featured a a collapsible area in the mouth area which allowed for an internal mouthpiece to be pressed into and held in the wearers mouth, providing a gas tight seal independent of the seal of the facepiece itself. This unusual feature was unique to the MkII and didn't appear on any subsequent designs. Additional protection against abrasion was achieved by giving the facepiece and hose a stockinette covering.
Air was inhaled and exhaled through a single assembly in the mouth area of the facepiece which featured a flapper type exhale valve as well as the internal mouthpiece. To this an extended hose was fitted, which allowed the attached Type A Filter to be slung in the carrier at the wearers side where it would be less likely to interfere with the wearers movements. The two single glass eyepieces are secured within metal retaining rings to allow for improved vision and use with optical equipment. It was secured to the wearers face by means of an adjustable six point elastic head harness.
The use of the MkII General Service Respirator by the Royal Navy appears to have been fairly short lived, with it being replaced by the MkIVA General Service Respirator by the late 1920s. The MkII does however feature in a considerable amount of period photographs, in particular those taken of the weekly courses held at the Anti Gas School in Devonport, which were made into postcards and distributed to course attendees. These, as well as other paper items such as cigarette cards and numerous press photos can be found with relative ease compared to contemporary examples of the MkII of which only one example is known to exist at the time of writing. Why they are so scarce is unclear, but it is likely a result of the few that were manufactured and issued being removed from service and replaced with the MkIVA which saw use in various configurations until the mid 1940s.
Royal Navy Ratings wearing the MkII General Service Respirator. Note the carrier position on the wearers left hand side and the long hose which allows the respirator to be stowed and the filter carried in a non obstructing location.
The design of the MkII was certainly one of the more interesting respirators to be developed at Porton Down during the inter-war period. It could perhaps be described as being needlessly complicated and likely expensive to produce due to several of the design features present, but it remains a unique and interesting approach to addressing the request for a respirator specifically for naval use. Very little of the MkII was carried over and subsequently used on the MkIVA, the only parts which they have in common being the hose, Type A filter, and the carrier. The filter and carried both however were changed by the early 1930s.
A selection of period cigarette cards showing the MkII as worn in several different scenarios by both Royal Navy personnel and Royal Marines.
Drawings from the original patent demonstrating the collapsible portion of the facepiece which allows for the internal mouthpiece to be held in the wearers mouth.
The unique facepiece of the MkII General Service Respirator.