The Tornisterfiltergerät, a portable haversack filter, is standard equipment
in the German army, and is issued on a company basis. The filter is said to be
able to treat from 22 to 55 gallons of water per hour, according to the amount of
solid matter contained. Although the Tornisterfiltergerät was designed primarily
for clarification of water it is claimed by the Germans that this device will
effectively treat water that has been contaminated by dead bodies and similar
substances; however, it is expressly stated that the filter will not rid water of
objectionable odors nor is it effective against water containing chemical warfare
agents or substances in solution. Methods of water purification used by the
United States and Japanese armies were described
in Tactical and Technical Trends, No. 22, p. 33.
The gross weight of the filter and accessories is approximately 45 pounds. The
whole assembly is packed in a canvas case, provided with two carrying straps
so that it may be carried on the back, haversack-fashion. The assembly consists
of two parts, viz., spares and accessories box shown at (1) in the accompanying
sketch, and the filter; the box contains six pockets, each of eight spare filter pads;
also a cleaning brush and instruction manual.
The filter consists of a chamber through which water is forced by means
of a pump (2), actuated by a handle (3), the grip of which is hinged and can be set
at right angles to the shaft, as shown. The pump is supplied with water through a
reinforced rubber intake pipe (4), terminating in a metal strainer (5). The standard
length of the intake pipe is probably about 6 feet 7 inches. Water is delivered to
the filter chamber through the delivery pipe (6). The filter chamber is contained
between a front plate (7) and rear plate (8) which are held together by four tie-bolts
and wing nuts (9). The two lower bolts are hinged to the rear plate and they can
be swung outwards when the filter chamber is to be dismantled. The wing nuts
can be tightened by means of a key (10) which is normally located on the bar (11).
At (12) on the front plate is an air valve, with a safety valve (13) and (14) the water
outlet. Inside the filter chamber are four screens (15), provided at one side
with top and bottom annular porcelain projections which fit together when the
screens are in position, forming a continuous water channel. Alternating with
four screens (15) are three frames (16), also fitted with annular porcelain
projections. Between each screen and frame, and between the two outer screens and
the front and rear plates, are eight filter pads (17).
b. Method of Operation
Water is sucked by the pump (2) into the strainer (5) and intake pipe (4)
through the delivery tube (6), past the air valve (12) and safety valve (13) into the
upper and lower channels formed by the porcelain projections on the frames (16).
From each of these two channels three small openings (18), one in the center of
each porcelain projection, lead to the inside of the frame; the water is forced
through these and then through the filter pads (17) into the screens (15), where
it goes into the upper and lower channels formed by the porcelain projections on
the screens, and can be collected at the water outlet (14).
c. Method of Assembly
Remove and roll up the canvas cover. Unscrew the 4 wing nuts, Move the
2 lower tie-bolts outwards. Pull the front plate (7) forward. Remove the screens
(15) and frames (16). Insert 8 filter pads in position so that they rest on the cross
bars on the lid of the spares and accessories box, so that the rough side of
the pad faces toward the frame. Push back the front plate (7). Swing the 2 lower
tie-bolts back into position on the front plate. Tighten the wing nuts, first by hand
and finally with the key (10). Place the strainer (5) in the water, making sure
that it does not sink into mud. Open the air valve (12) by putting the handle in the
vertical position. Fix the grip on the pump handle (9) at right angles to the shaft,
and begin to pump slowly. As soon as water issues from the air valve, close the
valve and continue pumping until water begins to issue from the outlet (14).
d. Changing Filter Pads
Cease pumping. Open the air valve. Unscrew the four wing nuts. Dismantle
the front plate, screens and frames. Remove, and if possible, bury the used
filter pads. Carefully rinse down the front and back plates, screens and frames,
then brush them, and finally rinse them again. Take eight new filter pads and
insert them as directed in method of assembly instructions.
e. Care and Maintenance
After it has been used the filter should be dismantled, washed, and thoroughly
dried. The strainer should be unscrewed, cleaned and reconnected. As soon as the
parts are completely dry the filter should be reassembled without filter pads, the
outer edges of the screens and frames covered with a thin layer of grease, and
the canvas cover replaced.