A Long Stretch: Large buildings mean longer hoselines

FIRE ATTACK

A Long Stretch: Large buildings mean longer hoselines
By Greg Jakubowski

Large homes, schools, hospitals, malls, office buildings, churches, warehouses, industrial complexes and other large buildings all have one thing in common when it comes to fighting fires in them: Firefighters will likely need to stretch a hoseline longer than 200 feet from the engine company to the seat of the fire.

BUILDING CHALLENGES
Although the average home may be 1,000–2,000 square feet, some homes today measure 10,000, 15,000 or even 20,000 square feet—or more. This means firefighters will have to stretch 150–200 feet or more of hose just on the inside of the home to reach all areas.

Schools, particularly older ones, may not be equipped with standpipes. Hallways may be hundreds of feet long and may be one or more floors above ground level. Hospitals, malls and office buildings can have similar issues.
Churches, warehouses and industrial complexes may have expansive floor areas/process areas that require extremely long stretches of hose.

Even buildings with standpipes are only required to have outlets within either 150 feet or 200 feet from every room or area. This assumes that the attack line will be connected to the standpipe outlet closest to the fire. If it’s not, a longer stretch will be needed.

GO LONG
Many engine companies carry 150 or 200 feet of preconnected attack lines. These lines are normally 1 ½, 1 ¾ or even 2 inches in diameter. These same engine companies may also carry 150 or 200 feet of a single, larger attack line of 2 ½ or 3 inches in diameter. Some carry even more, up to 300 feet of hose. But no matter what type or length of hoseline you’ve got, the trick is to carry lines that are long enough and can supply enough flow to reach the type of fire situations you’ll face in your coverage area.

How can you get longer hoselines? The most common method is to use a preconnected 2 ½" or 3" line equipped with a gated wye or connected to an “apartment” or “high-rise” pack to allow for connection of a back-up line. (Departments without high-rise buildings in their area may question the need for standpipe packs, but the building types discussed above justify carrying them.)

You may even consider stretching a 4" or 5" supply line with a big wye to the front of the building to allow for the connection of multiple handlines at the scene with minimal friction loss. All incoming engine companies should be instructed or directed to take their high-rise packs to the fire building.

HOSE & NOZZLE CONSIDERATIONS

The length and diameter of your handlines, along with your nozzle types, should be based on the hazards/challenges in your coverage area. Do you need long lays, but not necessarily large flows (for example, in fire-resistant school buildings)? If so, perhaps a smaller-diameter handline will get the job done. If you need larger flows, such as in a mall, church or chemical process area, you need to consider larger-diameter handlines.
In at least one department I responded with, we carried 400 feet of 1 ½" attack line with a combination fog nozzle designed for university and garden apartment buildings. This attack line was designed to be pumped at 100 psi at the nozzle.

Friction Loss (psi) Per 100 Feet of Typical Fire Hose*
100 gpm 125 gpm 150 gpm 175 gpm 200 gpm
1 ½" 25 37 54 N/A N/A
1 ¾" 12 21 26 34 45
2" 6 10 13.5 18 24

* For comparison only. Numbers may differ based on age, model, and vendor of fire hose.

Based on the numbers in the table above, for a 400-foot-long attack line, you can flow 100 gpm from a standard fog nozzle on a 1 ½" line by pumping 200 psi at the pump panel, not accounting for elevation. Changing the attack line to a 1 ¾" line will allow you to still flow 100 gpm, but pump the line at only 150 psi. With a 200-psi pump pressure, you can pump almost 150 gpm on that same 1 ¾" line. Increasing the line diameter to 2 inches allows you to pump almost 200 gpm with a 200-psi pump pressure. As you move to larger handlines and potentially higher pump pressures, the lines begin to become less maneuverable.

Using a smoothbore (solid) nozzle or low-pressure fog nozzle can positively impact the pump pressure and flows. A line with a smoothbore nozzle only needs to be pumped at 50 psi, vs. 100 psi for a standard fog nozzle. Putting a standard 15⁄16" smoothbore nozzle on the end of 400 feet of a 1 ¾" line requires a pump pressure of about 210 psi with a resulting flow of 185 gpm. Using a 2" handline with the same nozzle, you can achieve the same flow at a pump pressure of only 150 psi.

Attack hose, nozzles and other appliances should be pressure-tested at 300 psi, allow

Views: 84

Add a Comment

You need to be a member of My Firefighter Nation to add comments!

Join My Firefighter Nation

FireRescue Magazine

Find Members Fast


Or Name, Dept, Keyword
Invite Your Friends
Not a Member? Join Now

© 2019   Created by Firefighter Nation WebChief.   Powered by

Badges  |  Contact Firefighter Nation  |  Terms of Service