TM 10-4320-317-13
Section III. TECHNICAL PRINCIPLES OF OPERATION
1-14. Functional Description of TWDS. The Model 6 x 6 SP6 TWDS is a highly mobile water transport system. It
consists of pumping stations, storage assemblies, and distribution points. It is designed to distribute water for distances
up to 10 miles on level terrain.
1-15. Components of TWDS Group. The following paragraphs describe TWDS components.
a. Pumping Stations. Each pumping station consists of a trailer-mounted 600 GPM pump assembly, a check
valve, pressure-relief valve, butterfly valves, and several 6-inch diameter hose assemblies. The pump
assembly is powered by a 6-cylinder diesel engine. Refer to the applicable technical manual for operating
instructions.
(1) Leading Pump Station. Draws water from a large storage and distribution unit that is supplied by wells or
desalination operations. Feeds water downline through hoseline to first boost pumping station. Operated
in manual mode. Flow of water through unit is controlled by manually operating butterfly valves on
suction and discharge hoses. Pressure is regulated by adjusting engine speed.
(2) Boost Pumping Stations. Draws water from hoseline and feeds it downline to next boost pumping station
or storage assembly. After initial startup, boost pumps can be switched to automatic mode. Engine
speed will be regulated automatically. If pumping station fails, water can be routed through bypass hose
assembly to keep downline pumps primed. Flow of water is controlled by manually operating in line
butterfly valves. Pressure is regulated by adjusting engine speed.
b. Storage Assemblies. Each assembly can collect up to 20,000 gallons of water tapped from hoseline. Tank fill
rate is controlled by manually operating gate valve. The tanks are used for storage and to supply water to
distribution point.
c. Distribution Points. Each distribution point is made up of a 125 GPM pump, hypochlorination unit, and network
of hoses. The pump draws water from the storage assembly and feeds it through the hypochlorination unit to
be purified for drinking. Water is then routed through network of hoses to manual disbursing stations for
distribution.
(1) 125 GPM Pump. Skid-mounted, manually controlled, and directly driven by a small diesel engine.
(2) Hypochlorination Unit. Skid-mounted unit, powered by impulse diaphragm motor which operates on
water pressure. Amount of chlorine injected into water is controlled by adjusting pump stroke. Rate of
waterflow through unit is controlled by adjusting in-line valves. Once controls are set, unit usually
requires no further adjustments. It will inject the same dosage of chlorine into the water, regardless of
changes in flow rate. Operator must periodically refill the 5-gallon chlorine solution reservoir. Water at
manual disbursing stations is tested periodically by using color comparator kit.
(3) Hose Network and Manual Dispersing Stations. Rate of waterflow through the network is controlled by
adjusting in-line gate valves. Network ends at four manual dispersing stations where elbow valves or
nozzles are attached to hose ends. A 36gallon drinking water storage bag, suspended and fitted with
faucets, is used to dispense water to personnel for canteens and other small containers. The water bag
requires periodic refilling by operator.
d.
10-Mile Hoseline Segment. Transfers water to each major component in system. Consists of 500 feet
segments of collapsible hoseline that connect pumping stations and storage assemblies. A skid-mounted
pressure-reducing valve is installed in the hoseline to protect it from excessive pressure. Suspension devices
are used to route hose over obstacles in terrain, and road crossing guards protect hoseline when it crosses
roads. Hoseline can be capped if dead-end service is required, or it can feed another large storage and
distribution unit.
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