Hose Construction
Clean-up in today’s aggressive industrial environment requires specialized
products and hose is no exception. It is essential that hoses used in this
application have excellent resistance to oil and chemicals. They must be
lightweight, abrasion, and heat resistant. They must also be resistant to
environmental pollutants and capable of easy decontamination. For this
purpose, it is mandatory that the reinforcement be totally encapsulated in a
matrix of Synthetic Nitrile Rubber, compounded to optimize the above. To
avoid confusion with fire fighting hoses the hose shall be black or blue in
color. Old fashioned jacketed mill hose or coated products are not
acceptable. To ensure complete conformance, the resultant hose must meet the
following minimum requirements or it will be unacceptable.
Hose Physical Properties
Hose shall be evaluated in accordance with the principles and practices
listed in the National Fire Protection Association Standard 1961 (2002
edition) and related standards. When tested as such it shall have the
following properties:
Ultimate Tensile Strength
Tensile strength of the vulcanized rubber compound used in the hose shall
not be less than 1750 psig.
Ultimate Elongation
Ultimate elongation of the vulcanized rubber compound shall be not less than
500%.
Permanent Elongation
Permanent elongation of the vulcanized rubber compound shall be less than
24%.
Adhesion
The adhesion between samples of the reinforcement web and either the liner
or the cover shall exceed NFPA 1961 requirements. The sample width shall be
1 1/2” as called out in the standard.
Accelerated Aging Properties
When subjected to hot air oven aging at 158°F for 96 hours, the tensile
strength and ultimate elongation shall be at least 75% of the original
values.
Heat Resistance
When subjected to an internal static water pressure of 100 psi, the
hose shall withstand a surface temperature of 1200°F for at least 60
seconds without bursting.
Cold Resistance
Hose shall be capable of practical use down to -35°F
Ozone Resistance
When evaluated in accordance with standards ASTM D 1149 and ASTM D518,
procedure B, 70
hours at 118°F 100 pphm of ozone, the cover or liner shall show no visible
signs of cracking.
Chemical Resistance
Contamination by most chemical substances, oils, greases, hydrocarbons, and
exposure to sea water shall have no effect on the short or long-term
performance of the hose. A copy of the chemical resistance chart for the
hose shall be provided on request by the manufacturer.
Abrasion and Wear Resistance
Long term use is determined in no small measure by the abrasion resistance
of the cover of the hose. To ensure this is adequate, the hose, when built
to the weights listed, shall withstand the following abrasion tests:
Factory Mutual Method
Hose shall exceed the Factory Mutual Research Corporation test for abrasion.
This is listed in their Standard 2111 dated May 1995, section 5.8.
Underwriters Laboratories Method
When tested according to the method listed in Underwriters Laboratories Inc.
Standard 219, Hose shall withstand 5,000 cycles on the defined reciprocating
abrasion tester.
Taber Abraser Method.
When evaluated against the procedure listed in ASTM D2215 Reinforcement
shall not show signs of damage after 7,000 cycles.
Water Absorption
When tested against the procedure listed in MIL STD 24606 the maximum water
absorbance shall be no more than 0.5 lbs in a 50 foot length.
Couplings
The hose shall be fitted with lightweight, extruded aluminum alloy, hard
coated, rocker lug couplings. These shall be expansion ring type, NPSH
threads or as specified.
|
