1. ## Large diameter hose

Can anyone tell me how many gallons of water a 50ft length of 4" and 5" hose hold?

Thanks TR

2. I believe the formula is; Pi(radius squared)X length in inches divided by 231. (the # of sq.in. in a gal. of water) So I get 32.6gal. for the 4" and 50.9 for the 5". Thats if I remember my high school geometery correctly. But the gal. seem kinda low to me.

[ 07-17-2001: Message edited by: Ggg ]

3. I read somewhere it was 3/4 gallon per foot for 4" and 1 gallon per foot for 5'.

If that helps.

4. * * * * CORRECTION * * * *
I stand (or actually sit) corrected.
As Ggg pointed out here as well as from B.C. Myers via E-mail - I did indeed Screw up.

In my rush to get this calculated and posted during my lunch break I inadvertantly used the Diameter (4" & 5" respectivly) instead of the radius.

My apologies to Ggg for "correcting" that which was not in error and to everyone else for providing wrong information.
The corrected figures now appear below.

Pi = 3.14159
All Gal. referenced are U.S. Gallons
1 Gal. Water = 231 Cubic Inches
1 Gal. of Water (at 80 Deg F) = 8.3176 Lbs.
In^2 = Square Inches and In^3 = Cubic Inches

For 4" Hose
Pi X 2" Squared X 600" (50' X 12")
Pi X 4 In^2 X 600"
Pi X 2400 In^3
7539.8 In^3 *
7539.8 In^3 / 231 In^3 per Gal. = 32.6 Gallons *

32.6 Gal X 8.3176 Lbs per Gal. = 271.2 Lbs. *

For 5" Hose
Pi X 2.5" Squared X 600" (50' X 12")
Pi X 6.25 In^2 X 600"
Pi X 3750.0 In^3
11781.0 In^3 *
11781.0 In^3 / 231 In^3 Per Gal. = 51.0 Gallons *

51.0 X 8.3176 Lbs per Gal. = 424.2 Lbs. *

* - All Answers Rounded to Nearest Tenth

It should be noted that these calculations are approximate and "nominal" values for Diameter were used. If you wanted specific (i.e. Anal) answers - you should take an accurate measurement fo the Inside Diameter of your specific hose.

I tried to show all my Units & Work so if I did screw up then hopefully someone can see where (and tell me), because I too had to go back and look up a lot of stuff.

Felt pretty good though for a minute or two I thought I was back in college again.

Take Care - Stay Safe
Stephen
FF/Paramedic

Looks like I might need to head back to college again for a few remedial geometry classes - once again my apologies to everyone.

[ 07-19-2001: Message edited by: N2DFire ]

5. Hey rookie, I checked my formula with an old text and my first guess was correct. Thanks to N2DFire for confirming, but when I looked at the formulas there is a typo. The diameter sq. was used instead of the radius sq. I know what you mean N2DFire about that college feeling, it was kinda scary that I remembered the formula after all these years.

6. Gentlemen,
You can square the diameter and lose the Pi (3.14).
5" hose
5"x5"x600" = 15,000 cu in.

Multiply 15,000 by .7854(vol. of the cylinder inside of the square) = 11781 cu.in.

Divide 11781 by 1728 (cu. in. in a cu. ft.=6.8177083.

Multiply 6.8177083 by 7.485 ( gals. in a cu. ft. = 51.030546 gals.

Just a hobby and something I teach to our 10th grade Geometry students.

Lots of fun to play with but not too practical on the fireground. Great topic.

7. Food for thought, I have done some calculations on catastrophic failures on 5" LDH . The way the hose is constructed the most likely place to occur is at the coupling. Here a few examples comparing 3" line with 5" line.

3" hose with 40 PSI at failure = 282 pounds of force
5" hose with 40 PSI at failure = 782 pounds of force
3" hose with 70 PSI at failure = 494 pounds of force
5" hose with 70 PSI at failure = 1372 pounds of force
3" hose with 120 PSI at failure = 847 pounds of force
5" hose with 120 PSI at failure = 2352 pounds of force
3" hose with 150 PSI at failure = 1059 pounds of force
5" hose with 150 PSI at failure = 2940 pounds of force

100' dry section of 5" hose weighs approximately 106 pounds with couplings is weighs approximately 114 pounds.

In 100' section with water there is approximately 102 gallons of water weighing approximately 856 pounds.

Just the weight of the water and the hose the total weight of 100' of 5" hose is 1000 pounds.

The intake values I have been exposed to are the piston type valve with and adjustable relief valve attached.
The relief valve is adjustable from 100 PSI to 200 PSI. The other valve is the butterfly which does not a relief valve.

It is my experience with the piston valve that it must be open slightly before charging the supply line. If this is not done the valve will not open because there is too much force on the valve. If you open the valve slightly the pressure is even on both sides of the valve and it is very easy to open. The first time we tried to use this valve on a hydrant with 120 PSI static pressure we could not open the valve with the handle, but be the ingenious firefighters we are we tried using a pry bar. We were unsuccessful in opening the valve, but we sure broke the handle. A lesson learned.

The butterfly valve was a problem because our water system is very old we were getting a lot of grit in the valve and this caused serous leaks in the valve. Also this valve does not have a relief valve and this is dangerous when using LDH hose.

As for using LDH hose when pumping a ladder I believe this is not practical. The LDH hose is tested a 200 PSI and NFPA states you should not pump it over 185 PSI. We did some flow testing on a 100' ladder with a pre plumed waterway, our goal was to flow 1000 GPMs. To accomplish this we had to pump 245 PSI at the base of the ladder to overcome the friction loss, nozzle pressure and elevation. We also did flow testing on our tower ladders to flow 1500 GPMs. To accomplish this we had to pump 245 PSI at the base of the to overcome the friction loss, nozzle pressure, and elevation. This does not include the friction loss in the supply line.

Glenn

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