Page 36 - 2010-2022 hose manufactureing ability and guide

While suction hose is generally used to This can be done by extending the body wire to
convey liquids, vacuum hose carries air under a the ends of the hose, or by attaching a light
partial vacuum. Vacuum hose is reinforced to static wire to the outermost coils of the body
resist collapse and maintain its shape under wire. This lighter wire is led through the ends of
rough handling and/or mechanical abuse. It does the hose and attached to the couplings. In non-
not require the heavy construction of suction wire reinforced hose, a static wire can be
hose because the dry materials generally included in the hose body.
conveyed are much lighter in weight than The tendency has been toward a grounding
liquids and the vacuum is usually less than for connection completely separate from the hose or
normal suction service. to have the tube or cover of the hose

ELECTRICAL CHARACTERISTICS conducting. Examples would be sand blast hose
OF HOSE with conducting tube or aircraft fueling hose
with a conducting cover. An internal static wire
Conductive Hose could break or lose contact with the couplings
Static wires and conductive rubber components and not be detected visually. This could occur
are used in hose to help prevent static electricity from an unusual stress imposed on the hose.
build-up and subsequent a discharge as a spark. Non-Conductive Hose
Electrical engineers differ in opinion on the
effects of static electricity and the means of In some specific applications, especially
dissipating it. around high voltage electrical lines, it is
imperative for safety that the hose be non-
In handling gasoline and other petroleum-based conductive. Unless the hose is designed
liquids, recognized national associations and particularly to be non-conductive and is so
companies have conflicting opinions on the branded, one dare not conclude that it is non-
need for conductive hoses. conductive. Many black rubber compounds are

Until a consensus is reached among all inherently and inadvertently conductive. Non-
associations, laboratories, and users and a conductive hose is usually made to a qualifying
standard practice is established, it is essential standard that requires it to be tested to verify the
that the user determine the need for static desired electrical properties. An electrical
bonded hose based on: (a) the intended use of resistance test method is described in Chapter 6.
the hose; (b) instructions from the company’s The hose is usually non-black in color and
Safety Division: (c) the insurer; and, (d) the clearly branded to indicate it is designed for
laws of the States in which the hose will be non-conductive applications.
used.
Some types of hose include a body
reinforcing wire. This wire can be used for
electrical continuity provided that proper
contact is made between it and the hose
coupling.

UNLESS A HOSE IS DESCRIBED SPECIFICALLY AND CLEARLY BRANDED TO BE
CONDUCTING OR NON-CONDUCTING, IT MUST BE ASSUMED THAT THE
ELECTRICAL PROPERTIES ARE UNCONTROLLED.

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