The PMN series of blast anti-personnel mines were designed and manufactured in Russia. They are one of the most widely used and commonly found devices during demining operations.
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The design of the PMN-1 mine dates from the late 1950s. It is particularly deadly because it contains an unusually large explosive filling when compared to most other anti-personnel landmines. For comparison, most anti-personnel blast mines (e.g. the VS-50) contain around 50 grams of explosive, which typically destroys all or part of a victim's foot. In marked contrast, a PMN-1 contains 249 grams of explosive which can easily destroy a victim's entire leg (often requiring amputation well above the knee) in addition to inflicting severe injuries on the adjacent limb, which may also require some form of amputation.
These mines are palm sized and cylindrical in shape. The PMN-1 has a bakelite case (brown or black in colour) with a black rubber pressure-plate and contains TNT explosive.
The PMN-1 mine is armed by removing a steel ring-pull at the end of the horizontal fuze. When in position, the pin on the end of the ring-pull holds a spring-loaded striker back from the stab-detonator. Pulling out the ring-pull starts an arming delay, which comprises a thin steel wire (held under tension by the spring-loaded striker) which must cut through a small strip of lead before it is freed. The process of cutting through the lead strip takes between 2 and 12 minutes, depending on ambient temperature. After the wire has completely cut through the lead strip, the spring-loaded striker is freed and slides forward a few millimetres before stopping, blocked by the sliding gate of the pressure plate mechanism. At this point the mine is fully armed i.e. the only thing holding back the spring-loaded striker from the stab-detonator is a weak creep-spring on the pressure plate mechanism. Subsequently, any downward pressure on the pressure plate (i.e. when someone steps on the mine) overcomes the upward pressure of the creep-spring and pushes down the sliding gate that holds back the spring-loaded striker. This action frees the striker which flips forward into the stab detonator, firing both it and the adjacent tetryl booster which triggers detonation of the main TNT explosive filling.
The PMN-2 mine casing is made from injection-moulded plastic. In general, the colour is leaf-green, but occasionally brown examples may be encountered. The top of the mine has a black rubber X-shaped pressure plate. The filling is an RDX/TNT based explosive that is quite similar to Composition B. As with the PMN-1, the PMN-2 has an unusually large explosive filling when compared to many other anti-personnel landmines.
One significant difference between the PMN-1 and PMN-2 is that the PMN-2 (an early 1970s design) contains a more modern fuze with an integral baffle beneath the pressure plate. This and the X-shaped design of the pressure plate makes the PMN-2 much more resistant to traditional explosive mine countermeasures, which use sudden blast overpressure to detonate mines. In contrast, the PMN-1 (a 1950s design) can successfully be cleared by such methods.
The PMN-2 fuze features an arming delay. When the arming key is rotated and removed from the mine, the arming pin is sheared. This allows the air-bellows inside the mine to be inflated by the compression spring, which in turn lifts a “safety” bar from the path of the slide, unblocking its travel. The arming delay on a PMN-2 is significantly shorter than that of a PMN-1.[1]
The cover of a PMN-4 mine is black and the body is reddish brown. The diameter is 95mm and the height is 46mm. The explosive charge weight is 55 grams and the total weight of the mine is 300 grams. PMN-4 mines contain a significant amount of metal components, so they are readily detectable with standard mine-detectors. Details of the fuze mechanism are scarce, but it is a delay-armed, pressure-fired blast-mine. Given that the PMN-4 was designed approximately 15 years after the PMN-2, and its explosive filling is significantly smaller, a PMN-4 fuze is possibly more sophisticated than its predecessor, in order to compensate for having less destructive power.[2]
It is considered extremely dangerous to disarm PMN mines by removing the fuze, unless they have only recently been laid and are in good condition. Even if this is the case, what appears to be a standard PMN-1 mine may in fact be the PMN-3 or MC-3 versions, which feature an integral anti-handling device which is specifically designed to kill deminers. In any case it is very easy to give any PMN mine an anti-handling feature by attaching or glueing a pull-fuze to it. Therefore, the standard render-safe procedure for PMN-1 mines is to destroy them in situ using a small explosive charge.
