A thirst-quenching role for Fybroc Pumps

A transportable water-purification
system owes its transportability and ease of deployment to six Fybroc FRP
The Expeditionary
Unit Water Purifier, or EUWP, is a lightweight, transportable system capable of
purifying, storing and dispensing potable water in any austere environment from
virtually any water source.

applications range from military troop support operations and homeland defense
to disaster relief, humanitarian aid and municipal water supply.

(Figure 1) consists of an ultra-filtration (UF) membrane process to remove
suspended solids, followed by a reverse osmosis (RO) desalination process to
remove dissolved solids. Raw water is drawn from a surface or underground
source, passed through the UF and RO modules, and stored in bladders until it
is needed.

first-generation demonstration unit can produce about 100,000-gpd of potable
water from a seawater source, or more than 200,000-gpd from a freshwater

Light Weight is Critical
The Generation I EUWP Demonstrator includes supplies for 100 hours of
operation, 40,000-gal of product water storage, and a 60-kW generator.

A team of
four water treatment specialists using a 10k forklift can set up the equipment
and be producing potable water within six hours. It can operate unattended,
with only periodic preventive maintenance performed by the operator, and can be
converted to an electric-powered system for extended-duration missions.

equipment consists of two separate 8 x 8 x 20-ft ISO-configured platform with a
total system weight of less than 35,000-lb.

mainly as a transportable system to provide potable water to military troops,
the EUWP is designed to be moved into the battlefield with a single sortie of
the C-130 military transport aircraft. The requirement for airborne transport
helped define the allowable size and weight – if the EUWP weighed too much, the
range of the C-130 would be reduced because it would have to take less fuel to
account for the weight.

for disaster relief, moving water – which is very heavy – by truck is a
resource-intensive activity. It is easier to move a lightweight EUWP by truck
or aircraft to a central location and distribute water from within the disaster
zone, freeing up resources for other relief activities.

of the need to minimize weight, the EUWP's pumps are made of
fiberglass-reinforced plastic (FRP). An FRP pump weighs approximately 25
percent of the equivalent carbon steel pump. "Using FRP pumps allowed the
EUWP to come in under the target weight," explains Mike McCain, business
manager at Village Marine Tec. (Gardena,
CA) which developed the
Generation I EUWP.

FRP Pumps: The Heart of the System
The EUWP system
employs six FRP pumps – five ANSI close-coupled pumps with one self-priming
close-coupled pump.

With the
exception of its two-piece casing, the self-priming pump is interchangeable
with its same-sized ANSI counterpart. The raw-water feed pump, a 3X4X10
self-priming, close-coupled unit designed to have vertical lift of 25-ft on a
50-ft inlet, draws raw water from the source and feeds it to the UF boost pump
at the inlet of the UF skid. This 3X4X8 pump pushes the water through a
200-micron strainer and into the UF feed tank.

water is pulled from the feed tank by the UF feed-and-cleaning pump and pushed
through the UF filter system into an intermediate holding tank. This is a dual
duty 4X4X10 pump, as it is called on to fast-flush the UF cartridges in the
back-flush cycle and to circulate water through the system during the UF
cleaning cycle.  A separate 4X6X10 UF
back-flush pump is used in the back-flush cycle to pump large volumes of water
through the UF cartridges on a periodic basis.

Water is
pulled from the intermediate tank by the 3X4X10 RO feed pump and fed to the RO
skid. This is also a dual-duty pump and is used in the RO and UF cleaning

the RO product-water pump (3X4X8) pulls potable water from the storage tanks
and sends it to the user(s).

wetted components of the pumps are constructed of fiberglass-reinforced vinyl
ester resin. Only non-wetted parts are metallic: shafts and hardware are Type
303 stainless steel, and the bearing frame is polyester thermosetting powder
coated cast iron. O-rings are made of Viton, and the bearing frame is
epoxy-coated cast iron.

addition to light weight, other benefits of FRP pumps include corrosion
resistance, lower cost, longer service life and reduced maintenance compared to
metal pumps. "We did a search of the available pumps that met our
requirements. I've had good experience with these," McCain points out.
"Many have been running in installations around the clock and have proven
very reliable."

FRP and RO – Perfect Together
Osmosis is the
naturally-occuring movement of a fluid (e.g. water) through a semi-permeable
membrane into a solution of high-solute (e.g. salt) concentration, which tends
to equalize the concentrations of solute on the two sides of the membrane.

reverse osmosis, pressure is applied to the solution of higher concentration
(e.g. seawater) using a pump, which forces the fluid through the membrane in
the opposite direction of osmosis. The membrane prevents the salts and
contaminants from passing into the low-concentration solution.

product is a solution with a very low solute concentration on one side the
membrane (i.e. the drinking water). The reject (or brine) is a solution of very
high solute concentration on the pressurized side of the membrane.

osmosis was selected as the core technology for the EUWP because of its ability
to desalinate water with a wide range of salinity – from seawater to brackish
water – and its effectiveness against most water contaminants.

RO is
considered one of the best available treatment techniques for most classes of
chemicals. In addition, it requires less energy to desalt seawater than such
technologies as distillation and electrodialysis.

the raw water is saline and corrosive, and the other processes in an RO plant
(such as cleaning) involve corrosive chemicals, the use of high-grade alloys or
nonmetallic components is always 
recommended.  Common stainless
steels (such as Type Types 304, 316 and 904) have limited corrosion resistance
in high-salinity applications, particularly very high brackish water and
seawater. Exotic alloys that would offer sufficient corrosion resistance are
very expensive. This means fiberglass-reinforced plastic is an economical and
reliable alternative for reverse osmosis desalination.

FRP has
been the material of choice for horizontal and vertical pumps performing
various functions throughout RO plants, specifically; seawater intake pumps;
filter feed pumps; intermediate booster or raw water transfer pumps; filter
backwash pumps; cleaning recirculation pumps; flushing pumps; permeate water
pumps; and neutralization pumps.

to Mohammed Saud, projects manager for Desalination System Design and
Engineering at Bushnak Group's Water and Environmental Services Company (WESCO;
Jeddah, Saudi Arabia), in the last several years alone FRP pumps have been
installed in numerous RO-based desalination plants, with capacities ranging
from 800,000 gpd to 6.6 million gpd, in Saudi Arabia, Oman, and India.

operates in blowing sand, dust and rain, at air temperatures from 32°F to 120°F
with water at 28°F to 105°F – all conditions that are well within the capabilities
of FRP pumps.

Gennaro A. "A Thirst-Quenching Role." Pumps & Systems June 2006.

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