ARTICLE 1
Comparative Analysis - The US M9 Series And Its Copies
_____In the later years of W.W.II, it became of importance that the US Chemical Warfare Service develop a lightweight gas mask for paratroopers and amphibious assault troops. The British had already developed such a mask called the Mk. I Light Anti-Gas Respirator (below left). Instead of attaching the filter canister to the face piece via a corrugated rubber hose, the Mk. I used a round filter with a large opening that was screwed into the left side of the face piece. This innovation enhanced head mobility and also eliminated other problems with dexterity caused by heavy filter canisters that were worn around the chest or at the side. Breathing resistance was also lowered because the soldier did not have to draw air up through a heavy corrugated rubber tube, as with most other W.W.II service gas masks. It is likely that the British Mk. I was the inspiration for the US M5-11-7 Assault Service Gas Mask (below center), which was introduced in late 1943. The M5-11-7 went on to be carried by US troops during the famous D-day assault on Normandy, making it a significant W.W.II collectable. The Assault Gas Mask was nothing more than a altered US Army M3 Lightweight Service Gas Mask. The chin area of the mask that usually had a hose attached was sealed off and a 60mm filter inlet was integrated into the left side of the neoprene face piece. A fabric neck strap was also added to the head harness to keep the face piece straight, as the mask had a tendency to shift on the wearer's head due to the extra weight on the left side. Despite the effort to create a serviceable lightweight combat mask, the M5-11-7 was made of neoprene rubber, and the face blank was prone to a stiffening effect known as "cold set". After the war, the C.W.S. set out to design a better lightweight mask that did not have the problems found with the M5-11-7. In the late 1940s, the E48 mask (below right) was developed. The E48 was an early prototype of the US M9 Field Protective Mask which was standardized in 1947. There were a few early production M9s made from black rubber like the E48 (below left, 2nd row). However, the bulk of all standardized M9s produced were made entirely from natural gray-green rubber with a black rubber oronasal cup fitted on the inside to aid the demisting process.

THE BRITISH MK. I LIGHT
ANTI-GAS RESPIRATOR

THE US M5-11-7 ASSAULT
SERVICE GAS MASK

THE US ARMY E48 MASK
_____The M9 was manufactured with a filter inlet on both the left side (below center) and on the right side (below right) which enabled either left or right handed weapon sighting.

AN EARLY PRODUCTION M9

THE US M9 FIELD PROTECTIVE MASK

THE US M9A1
(RIGHT SIDE FILTER INLET)
ABOVE: A US Marine ABC (Atomic/Biological/Chemical) team trains in Hawaii wearing M9 gas masks (July 1959).
_____The M9's original carrier was an upgraded version of the earlier M7 carrier (below left) which was issued with the M5-11-7 Assault Service Gas Mask. The M7 carrier was made of a rubberized duck materiel that could be rolled and snapped shut to make it water tight. The M9's carrier, designated the C15R1 used the same water proofing concept but was made of an olive drab duck materiel coated with rubber on the inside. Sometime around 1950, the M9 was upgraded to the M9A1 after a new carrier was introduced, designated the M11 carrier (below right). The mask itself did not undergo any changes.

THE M7 CARRIER


THE C15R1 CARRIER


THE M11 CARRIER
The M9 fitted with the M-4 Toxicological Protective Hood
THE US ABC-M21 ROCKET PROPELLANT GAS MASK
THE US M15 COMPRESSED AIR BREATHING APPARATUS
_____The M9 series mask came in three sizes: small, medium and large and proved to be a very comfortable mask that offered a high level of protection. To enhance the mask's protective capabilities, the M-4 Toxicological Protective Gas Mask Hood (above left) could be issued along with the mask. The face piece of the M9 was also used for the M15 Compressed Air Breathing Apparatus (above right) and the ABC-M21 Rocket Propellant Gas Mask (above center). So successful, the M9 design was copied by at least five countries, possibly more. The closest copies are undoubtedly the Serbian M-1 and the Korean KM9A1. These masks used a face piece, head harness assembly, filter and carrier that are virtually identical to the US M9. There is also the Serbian MC-1 (a civilian version of the M-1) made without the inner oronasal cup. Another copy made in Sweden, was also very close in design. The Skyddsmask-51 used a dark green rubber face blank and a larger rubber exhale valve cover, giving it a distinguishable appearance. In Finland, a slightly modified clone was produced, designated the m/61. There were several different m/61 variants manufactured, with the earliest type being also virtually identical to the US M9. The last version of the Finnish m/61 was manufactured with a peculiar hard plastic exhale valve assembly which doubled as a voice-mitter. A copy of the M9 was also produced by Bulgaria and was made of black rubber giving it an appearance very close to the Korean version.

THE SERBIAN M-1

THE SERBIAN MC-1

THE SWEDISH SKYDDSMASK-51

THE BULGARIAN M9 COPY

THE KOREAN KM9A1

THE FINNISH M/61 (1st MODEL)

THE FINNISH M/61 (2nd MODEL)

THE FINNISH M/61 (FINAL MODEL)
_____The US M9 series mask went on to be serviced by the US Army through the Korean War and all the way to the Vietnam era, where it was eventually phased out and replaced by the M17.


ABOVE: A DIAGRAM OF THE M9 EXPLODED
ABOVE: A diagram illustrating airflow through the M9.
ABOVE: A photo of an early production M9 as worn.

REFERENCES USED FOR THIS ARTICLE:

TM 3-205 - THE GAS MASK, MARCH 1951

TM 3-205/T0 14P4-1-31 - PROTECTIVE MASKS AND ACCESSORIES, APRIL 1955

TM 3-522-15 MASK, PROTECTIVE, FIELD, M9 AND MASK, PROTECTIVE, FIELD, M9A1, OCTOBER 1957

U.S. CHEMICAL AND BIOLOGICAL DEFENSE RESPIRATORS
By Christopher T. Carey
  ABOVE: A worker wearing a protective suit and a M9 gas mask carefully moves some radioactive metal (ca. 1954).
© NO FUTURE PRODUCTIONS