Fire Hose Liner Options
There are several options for fire hose linings.
The most common four are: PVC,ethylene propylene diene monomer (EPDM),
thermoplastic and impregnated/extruded polyurethane or nitrile rubber.
PVC and EPDM are typically the most
budget-friendly liner, applied by adhesive to the inner jacket. EPDM liners are
widely used in fire hose, yet as with any adhesive-applied liner, they can be
subject to delamination over the life of the hose. Routine hydrostatic fire
hose testing does not do much to detect this deterioration, and since there is
no easy way to inspect the inside of a hose, the only way to verify the hose is
holding up is to flow test it. This may be an easy endeavor for a small
department who has a smaller inventory of fire hose, but may be much more
difficult for larger departments, due to the massive amounts of hose in use.
Thermoplastic liners are also applied by
adhesive. They offer a slightly lighter-weight liner that can be less prone to
degradation, but they are also known for higher friction loss characteristics
and may be subject to faster burn-through. Thermoplastic liners are also are
not able to stretch as easily as EPDM liners, and are therefore more likely to
delaminate over time.
Extruded or "through the weave" liners
are becoming more popular on the market; several manufacturers now offer high
performance attack hose with this type of liner. During the manufacturing
process, the liner is applied in a liquid state to the fabric and seals itself
to the inner jacket, resulting in a virtually inseparable hose liner. Another
advantage of this liner is that it offers a more hydraulically efficient
waterway. Extruded liners are essentially made by using the same process as single jacket rubber supply hose is, where a thread weave molded into the
rubber gives it the strength to withstand pressure. This is a double-edged
sword, however, because the improved flow qualities also mean that the friction
loss values typically assessed by firefighters, pump operators and instructors
are significantly different than the actual flow performance of the hose. The
best way to see how the hose is performing is to conduct field testing with
calibrated flow test equipment.
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