Inspect Hose liners!

I am commonly asked to help departments with spec and purchase of hose.  Hose is a fleet of equipment.  It must work together with relatively similar characteristics, including, durability, friction loss, dry weight and charged hose weight.  All departments should develop a hose spec that meets their needs, not only today but into the service life of their hose fleet.

With a 10 year front line service life, and up to 5 additional years in reserve a mistake in purchasing can represent a 15 year mistake.  This is very similar to purchasing an Engine or Truck that has been improperly spec’d.

I have seen this time and again, delamination issues, hose that sticks together, hose that does not have similar friction loss, or wear characteristics and larger than necessary waterways.  This leads to significant impacts in the field.  Blocked nozzle, low flow, poor deployability, kinking, nozzle whip and generalized poor performance.   

One must remember that NFPA 1961 is now being treated as a minimum performance bar.  Some attack hand lines products just barely meet it when brand new.  If your department just requests NFPA 1961 compliant hose from their vendor year to year the quality and characteristics of the hose could vary significantly.

I have recently seen hose that expands over time causing hot nozzles and additional water weight at low PDP. I have seen delamination issues that produce very low flow at high PDP.  

There is also lightweight hose with such a small amount of material in it’s jackets that it fails in storage, or wears through the outer jacket in a single day of training. There are a number of additional agencies that have noted this problem. Worcester Polytechnic Institute has been tasked with trying to initially investigate thermal burn through of handline hose.  The ATF Labs and Arson Squad have be working on a project called “Determining failure times of interior fire attack hose lines resulting from external radiant energy exposure”  The failure point of some hose specs are absolutely stunning both studies should be out with in the next 12 months.  Both of these projects have been born out of the Boston double LODD of Kennedy and Walsh  

I have had detailed discussion with both of these entities, and expressed the need to return to a common sense level of material in attack handline hose.  Before the exotic is created and ordered we need to help the rank and file with what we have now.  Before the standard is changed to a "True Hose spec" and all problems addressed formally, you can purchase the best in the class of hose that exists now.  This would be hose with waterways that are not over sized for handline flows and not under built for interior fire duty.  Below is my desired spec for woven jacket hose. It may change as my knowledge grows, as with all things this is a learning process.     

1)     Double Jacketed (Nylon or Polyester or a blend) “Filler Yarns” are to be filament type to ensure adequate strength “Warp Yarns” are to be the spun / entanglement type to both resist cutting and abrasion, but allow load transfer when damaged. This construction should also ensure a large amount of the coating is thoroughly absorbed by both jackets during the protective coating process.

2)     EPDM rubber liner, minimum wall thickness of .040-inches with a preference towards vulcanized rubber adhesion of the liner and jacket.

3)     A minimum pick count of 9.5 picks per inch (increased strength and abrasion resistance).

4)     (Denier weights of filament and yarns to be determined based on goal weights).

5)     Withstand Abrasion Test defined in FM Class Number 2111 to 20,000 Cycles minimum with a goal of 30,000 Cycles.

6)     The outer jacket shall allow less than 1/16th -inch expansion under pressure below 200psi. Hose shall maintain its internal diameter through its service life under normal working conditions (not to exceed service test pressure).

7)     Goal Service Test Pressure of 400psi, but not less than 300psi.

8)     The inside jacket shall be manufactured using a reverse twill process to reduce friction loss.

9)     There shall be a durability coating of the outer jacket.

10)  1 ¾” Total Coupled Weight goal of 17-20 pounds per fifty feet section.

11)  2 ½” Total Coupled Weight goal of 25-30 pounds per fifty feet section.

12)  Manufacturer tested friction loss in the above spec in 2 9/16th -inch not to exceed 8psi per 50 feet at 250gpm or less than 7psi per 50 feet.

13)  Manufacturer tested friction loss in the above spec in 1 ¾-inch not to exceed 20 psi per 50 feet at 160gpm or less than 19psi per 50 feet.

14)  Obtain two coupled test lengths (100 feet) of each hose spec (1 ¾ & 2 9/16) in order to perform measurements of internal diameter and testing of handling/kinking characteristics.

15)  Obtain of each hose spec (1 ¾ & 2 9/16), two four-foot samples of hose, uncoupled in order to conduct destructive testing.  Or allow destructive above test of test lengths.

16)  Hose shall be fully NFPA 1961 complaint and preferably (full or partial) compliance with UL 219, FM Class Number 2111 and (Old spec MIL-H-24606B).

17)  An internal diameter that is the actual size of the marked hose size on the jacket 1 3/4-inch and 2 9/16-inch.

18)  Hose length that is within 1 inch of marked length.

You can see in the picture the red hose is nearly see through.  The thermo plastic polyurethane liner that routinely fails in its bonding / adhesion to the woven jacket.  The fancier TPU bonding or "through the weave" often ends up with mismatching elongation issues between outer and inter jackets leading to water way restrictions that are unpredictable. 

In the end no hose manufacture wants to produce hose that does not achieve a good ten years service life under a normal duty cycle.  Yet this still happens and I believe to be mainly a material engineering problem. Many people accuse me of not embracing new technology.  This is not the case, however I stick to what I know to be a good proven design first, and let someone else take the risk with the new.  Do not be the agency, which is unwittingly part of an experiment.  You will find your self talking with a manufacture representative focused on the "features" not the spec who asks: "Is that the clear, white or red liner?" (All with different performance realities) "Blue, I think?" you say. "Are you sure blue? Ok let me check something on our end."

Before having that uneasy and unnecessary conversation, I would recommend testing the following products until the True Hose is built.  Order the one that meets your needs.  I have no financial tie to these products and have received no compensation from the manufactures.

The current venerable old guard of handline attack hose, nothing fancy just a proven track record

Polyester Hose:

  • Ponn Supreme

  • Key Big Ten - Non FDNY spec (smaller ID)

Nylon Hose:

  • All American N-Dura

  • NAFH Dura-Built 800

Dennis LeGear