LDH Friction Loss

[MG3610]

Has anyone collected data on friction loss in various brands of LDH.

The manufacturers websites don't list any data and I'm curious how they stack up against each other.

We Use National Triple Duty 4" and 5" and Angus Hi-Vol 5"

Thanks

[chiefengineer11]

Has anyone collected data on friction loss in various brands of LDH.

The manufacturers websites don't list any data and I'm curious how they stack up against each other.

We Use National Triple Duty 4" and 5" and Angus Hi-Vol 5"

Thanks

For the sake of head math I've always used 7#/100' of 5" with 1000 GPM flowing. That's probably not too far off when you're dealing with woven hose such as Neidner, National, etc. Extruded hose such as Angus, Snap-Tite and others on the other hand, generally have lower loss. The reason is that as the extruded is pressurized it expands outwardly, that is, its diameter actually increases. As a result, the friction loss increase is at a much lower rate.

All hose expands when it's charged. Note when you lay out and charge your woven hose. It will "snake" just like your old 2-1/2 and 3" because of longitudinal expansion Your Angus, on the other hand, snakes very little because its expansion is outward.

[fireinfo10]

Any mfg will supply you with friction loss chart.

We use ATI 5" Jafrib
ATI Jafrib 5" @ 1000gpm has 1.84psi/100'
ATI Jafline 5" (doublejacket) @1000gpm his 4.1psi/100'
(both 10yr warranty)

[SpecCapt]

From Key Fire Hose Corp.

http://www.keyfire.com/FlowChart.pdf

[MG3610]

Key's data appears merely theoretical (based on true diameter). The issue is that with different types of hose construction, diameters flex a bit (some by almost 1/4", so I've heard).

Angus sent me data in an email showing actual losses and their formula based on true testing. I'll have to post that when I pull it off my email at the firehouse this week.

[fireinfo10]

Key's data appears merely theoretical (based on true diameter). The issue is that with different types of hose construction, diameters flex a bit (some by almost 1/4", so I've heard).

Angus sent me data in an email showing actual losses and their formula based on true testing. I'll have to post that when I pull it off my email at the firehouse this week.

A hose mfg is going to publish calclated data based on static diameter? Unlikely, as unless their hose is crap the actual values are going to show them in a much more favorable light.

[SpecCapt]

I am curious as to why you are looking for the friction loss in such minute detail. Friction loss calculations for field operations are rule of thumb, and best done in round numbers. A pump operator has much more to think about than whether or not the friction loss is in 800 feet of 5” hose is 6.5lbs. per hundred or 6.3lbs per hundred. (We use 7lbs per hundred.) They also don’t have the time or the necessary information to figure it out, and frankly I would not want them spending their time or focusing their attention on that when something is burning.

I keep three Friction Loss Charts for reference and training purposes, the Key Fire Hose chart, Elkhart Brass chart and one from the US Navy. While there are minor differences between them the differences are just that minor.

Many years ago after a mind numbing semester of Fire Service Hydraulics the course instructor, a Battalion Chief from a city not only with a fairly heavy fire load but also some real terrain challenges made the follow statement, of course it was the last day of class, had it been the first no one would have been back. “When you are pumping at a fire and you not give the guys enough water they will yell at you, when your giving them too much water they will yell at you. If nobody’s yelling at you you’re probably doing fine.” An over simplification? Yes, absolutely. But a lot of wisdom in that statement also especially in today’s Fire Service where we tend to over think and over complicate things.

[chiefengineer11]

I am curious as to why you are looking for the friction loss in such minute detail. Friction loss calculations for field operations are rule of thumb, and best done in round numbers. A pump operator has much more to think about than whether or not the friction loss is in 800 feet of 5” hose is 6.5lbs. per hundred or 6.3lbs per hundred. (We use 7lbs per hundred.) They also don’t have the time or the necessary information to figure it out, and frankly I would not want them spending their time or focusing their attention on that when something is burning.

I keep three Friction Loss Charts for reference and training purposes, the Key Fire Hose chart, Elkhart Brass chart and one from the US Navy. While there are minor differences between them the differences are just that minor.

Many years ago after a mind numbing semester of Fire Service Hydraulics the course instructor, a Battalion Chief from a city not only with a fairly heavy fire load but also some real terrain challenges made the follow statement, of course it was the last day of class, had it been the first no one would have been back. “When you are pumping at a fire and you not give the guys enough water they will yell at you, when your giving them too much water they will yell at you. If nobody’s yelling at you you’re probably doing fine.” An over simplification? Yes, absolutely. But a lot of wisdom in that statement also especially in today’s Fire Service where we tend to over think and over complicate things.

The ability to successfully work the head math and solve operational problems is rooted in a thorough understanding of the two basics that govern all that we do as suppliers of water to the folks at the smoky end: The physics and the math.

When we know the pure math we can convert it to head math with reasonable accuracy. Anything else is a pure guess - doesn't even rate as a SWAG.

Ditto physics - when we understand the physics of what we're doing we're in a position to understand and work out operational and equipment problems, even ones we've never seen before.

Stay safe out there, everyone goes home!

[MG3610]

I am curious as to why you are looking for the friction loss in such minute detail. Friction loss calculations for field operations are rule of thumb, and best done in round numbers. A pump operator has much more to think about than whether or not the friction loss is in 800 feet of 5” hose is 6.5lbs. per hundred or 6.3lbs per hundred. (We use 7lbs per hundred.) They also don’t have the time or the necessary information to figure it out, and frankly I would not want them spending their time or focusing their attention on that when something is burning.

I keep three Friction Loss Charts for reference and training purposes, the Key Fire Hose chart, Elkhart Brass chart and one from the US Navy. While there are minor differences between them the differences are just that minor.

Many years ago after a mind numbing semester of Fire Service Hydraulics the course instructor, a Battalion Chief from a city not only with a fairly heavy fire load but also some real terrain challenges made the follow statement, of course it was the last day of class, had it been the first no one would have been back. “When you are pumping at a fire and you not give the guys enough water they will yell at you, when your giving them too much water they will yell at you. If nobody’s yelling at you you’re probably doing fine.” An over simplification? Yes, absolutely. But a lot of wisdom in that statement also especially in today’s Fire Service where we tend to over think and over complicate things.

I don't want decimal point details. What I do want to know is what the differences are. Your 7 PSI/100 is great if flowing 1000 GPM, what do you do when you are supposed to be delivering 1500 or 2000? F*** it, just guess, right? Its about double for 1500 and quadruple for 2000 (by the theroetical values at least). 7 doesnt show up on a gauge, so do you use 5 or 10?

For example; Ponn Conquest 1 3/4" hose has 20 PSI per 100' of FL at 180 GPM, most other brands are about 40. Thats a big difference.

Friction loss theoretical values designed around old rubber lined hoses have not adjusted well for alot of the new hose on the market. With that issue at hand, I am asking my question.

The pump charts we make up for our rigs are based on the performance of our hose, not theroetical values. The numbers we got are more than a few tenths off.

I have seen many a fire where they guys on a nozzle flowing 50 GPM were happy as a clam, as was the pump operator and the building merrily burned down in front of them. Nobody thought anything of it except "how bad of a fire it was."

Looks like we are one step ahead of you too , we made the pocket friction loss cards into 8 1/2" x 11" laminated charts with our pump pressures on front and a friction loss chart on the back.

[fireinfo10]

I am curious as to why you are looking for the friction loss in such minute detail. ...

Minute detail???

You don't see there is significant difference between 7psi/section and 2psi/section that might impact your operations?

[JMac73]

if this that much of an issue for you get some type of inline gauges and do a test. i on the other hand am too busy runnig 20 + calls a shift to even begin to tackle this min numming question.

[MG3610]

if this that much of an issue for you get some type of inline gauges and do a test. i on the other hand am too busy runnig 20 + calls a shift to even begin to tackle this min numming question.

Thank you for your meaningful contribution.

[FIREMECH1]

if this that much of an issue for you get some type of inline gauges and do a test. i on the other hand am too busy runnig 20 + calls a shift to even begin to tackle this min numming question.

Good thing you run med calls and not fire. ~

???

[SpecCapt]

MG,

Well you have brought up a couple of good points, as far as being ahead of us no debate from me. As I tell people we are so busy going around in circles we forgot how to go forward.

No F*** it is not acceptable, going above 1000 GPM we double friction loss for every 500 gallons, again we are dealing with operational guidelines to get the operators set-up and flowing water then refinements can be made.

Correct, 7 does not show up on the gauge but 15 (7x2=14), 20 (7x3=21), etc. do. With field calculations for friction loss we teach to use the higher number or round off up. The residual pressure at the pumper receiving water should never drop below 20psi a little more, great. This should give the pump operator supplying the handlines a cushion should the excrement hit the whirling blades. Communication between the pump operators is critical for successful water supply.

Your question at the beginning of this thread asked about friction loss in LDH, not handlines, not nozzle pressures, this is a whole different issue and the water flow/friction loss calculations are much more critical.

Fireinfo,

Yes minute detail, the difference between the a section of hose with a 2psi friction loss and 7psi friction loss when I am supplying 1000 or 1500 GPM is not going to impact to my operations. Remember I am addressing LDH and high volume water supply operations here NOT handline operations.

My department and I suspect many others here do not have the luxury of buying what fire hose we want, we don’t get new hose with pumper, and hose is rarely if ever replaced in full loads. I get what is on state contract, or I have to go out to bid. It is entirely possible, and probable that on a 1 ¾” handline there will be two or three different manufacturers products connected to each other. So a reasonable rule of thumb needs to be in place so that a pump operator can supply what the interior firefighters need.

Also I looked over the entire friction loss chart from ATI, as the 1.84 for the Jafrib seem kind of low, there is a typo, confirmed by ATI on the chart. While their friction loss calculations are still impressively low the friction loss for Jafrib 5” @ 1000 GPM is 3.05psi. Wonder how you figure or measure 5/100ths of a pound of friction loss in flexible hose? A burr inside a coupling would cause more than that.