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Filters listed in this article are known to contain materials hazardous to health Exercise caution when handling and storing. Refrain from using these filters. Seek medical advice if you have any concerns. |
The 70M filter canister is a Hungarian-made 40mm (GOST thread) NBC filter issued for military and civil defence purposes. Introduced during the 1970s, the filter, issued for many Cold War-era masks.
Overview[]
The 70M filters come in a dark-olive coloured 110mm diameter cylindrical aluminium-magnesium alloy canister with the same coloured cap. (The filter is nearly identical with the one on the PMG and the shape is identical to the Medicor industrial filters) The later ones have a plastic cap on the bottom, not rubber.
Substances[]
The lower section contains special FMB paper in 20mm high concentric folds (surface area is 600cm2). This paper is mostly composed of sulfite cellulose, but it contains 4-6% asbestos too. According to workers from Medicor in the mid 80s asbestos is statred to be phased out from these filters. Unfortunately there is no concrete date after which the filters are safe but there is a height difference between the old asbestos and newer asbestos free ones so comparing heights is the only good option to find an asbestos free filter (usually filters made after 1987 are safe). The only problem with this is that it requires two or more filters to identify an asbestos free filter. The upper section contains G5 (the same as the Soviet K-5u) activated charcoal granulates impregnated with ammonia which carried the K5M compound into the charcoal (the K5M contains 6% CuO, 1,5% CrO3 and 0,05% Ag2O - in g/g%, compared to the mass of the impregnated charcoal). Average protection time was more than 4 hours in medium contamination (>50mg/m3 sarin).
Markings[]
Three markings can be found on the filter (example filter on the pictures):
- Manufacturing year is under the bottom cap (87=1987)
- The four digits on the lower side are the month and day (04 16= April 16th)
- The printed digit is the serial number (18th series of 1987)
Developement[]
Because of the Soviet license first the 70M filter was much more similar to the EO-18k, however on the 1969 70M mask trials most problems were caused by prototype and series early filters. It leaked too much charcoal dust and producing the FMB filtering paper also deemed much more complicated than it was expected, to solve these problems the body of the filter was redesigned, the charcoal was changed to an ammonia impregnated one and the FMB paper was silghtly modified as well.
References[]
- Munkásőrség: Kézikönyv az alegységparancsnokok felkészüléséhez (book-1980)