Page 422 - Cat4800-Oct2011

408 Parker Industrial Hose Customer Service
866 810 HOSE (4673) 800 242 HOSE (4673)
Strongsville, OH South Gate, CA
Eastern USA Western USA
www.safehose.com
e-mail: indhose@parker.com
Safety & Technical Information
Physical Properties After Exposure to Oil
Class Volume
Change Maximum
Tensile Strength
Retained
Class A
(High Oil Resistance)
+25% 80%
Class B
(Medium/High
Oil Resistance)
+65% 50%
Class C
(Medium Oil
Resistance)
+100% 40%
Te above ARPM guideline does not imply compatibility
with all oil based fuids. Tere are many grades of rubber
compounds that meet ARPM Class A oil resistance
requirements. Some compound grades will be fne for
multipurpose applications, while higher grades would be
required for more rigorous applications.
Oil resistant hoses for multipurpose service tend to be
more economical than hoses specifcally designed and
recommended for highly refned fuel service. Tese
multipurpose hoses, even if they feature an ARPM
Class A tube, are not necessarily recommended for use
with highly refned fuels. Furthermore, many chemical
resistance charts represent data developed from testing
of a typical grade of compound used for that family of
fuids. For example, “nitrile” may show compatibility with
gasoline, but the nitrile that was tested is likely the nitrile
used in gasoline dispenser hose, as opposed to the nitrile
commonly used in multipurpose hose.
When selecting a hose for highly refned fuels such as
aviation fuel, biodiesel, diesel, ethanol, gasoline or
kerosene, be guided by the hose manufacturer’s recom-
mendation to use a hose designed and manufactured for
that specifc application and/or fuid. Contact Parker for
further information.
Suction and Vacuum
Hose is constructed with high adhesion between the tube
and the carcass to prevent tube separation. Most hose is
used for pressure service; however, some applications
require the hose to resist collapse in suction and vacuum
service. Such hose is subjected to crushing forces because
the atmospheric pressure outside the hose is greater than
the internal pressure. Te hose can collapse and restrict
the fow unless the hose is constructed to resist these
pressure diferentials. Te most common method of
preventing hose collapse is to build a helical member(s)
(wire or thermoplastic) into the hose body. Te size and
spacing of the helix depends on the size of the hose and
the pressure diferential. In applications approaching a
perfect vacuum, most of the plies of reinforcement are
applied over the helix.
Suction hose must be specifcally designed for the service
for which it is used. Each element — tube, reinforcement,
size, spacing, and location of the helix —must be carefully
considered. While suction hose is generally used to convey
liquids, vacuum hose carries air under a partial vacuum.
Vacuum hose is reinforced to resist collapse and maintain
its shape under rough handling and/or mechanical abuse.
It does not require the heavy construction of suction hose
because the dry materials generally conveyed are much
lighter in weight than liquids and the vacuum is usually
less than for normal suction service.