Environmental Engineering Reference
In-Depth Information
figure 4.22 Wrapped hose.
which encourages laminar flow and prevents turbulence. Several plies
(layers) of woven cotton or synthetic fabric make up the reinforcement.
To achieve its resistance to corrosive fluids, the tube is made from a num-
ber of synthetic rubbers. It is also used in sandblasting applications.
4.11.3.3.5 Wire-reinforced hose
In this type of hose, wires wound in a spiral around the tube, or inside
the carcass, in addition to a number of layers of wrapped fabrics provide
the reinforcement (see Figure 4.23). With inner diameters of 16 to 24 in.
common, this type of hose is used in oil suction and discharge situations
that require special hose ends, maximum suction (without collapsing),
or special flexing characteristics (must be able to bend in a small radius
without collapsing), or a combination of all three of these requirements.
4.11.3.3.6 Wire-Woven hose
Wire-woven hose (see Figure 4.24) has cords interwoven with wire
running spirally around the tube; it is highly flexible, low in weight, and
resistant to collapse even under suction conditions. This kind of hose is
well suited for negative pressure applications.
4.11.3.3.7 other Types of nonmetallic hose
Hoses are also made of other nonmetallic materials, many of them
nonreinforced; for example, materials such as Teflon®,
®
, Dacron
®
, poly-
ethylene, and nylon are being used in the manufacture of hose. Dacron
remains flexible at very low temperatures, even as lows as -200°C ( - 3 5 0°F),
nearly the temperature of liquid nitrogen. Consequently, these hoses
are used to carry liquefied gas in cryogenic applications. Teflon is often
used where corrosive fluids and fluids up to 230°C (450°F) are to be car-
ried; it can also be used at temperatures as low as -55°C (-65°F). Usually
sheathed in a flexible, braided metal covering, Teflon hoses are well pro-
tected against abrasion; they also have added resistance to pressure.
Nylon hoses (small-diameter) are commonly used as air hoses, sup-
plying compressed air to small pneumatic tools. The large plastic hoses
(up to 24 in.) used to ventilate manholes are made of such neoprene-
coated materials as nylon fabric, glass fabric, and cotton duck. The cot-
ton duck variety is for light-duty applications. The glass fabric type is
used with portable heaters and for other applications involving hot air
and fumes.
