Low Pressure Break Apart Nozzles

Show 40 post(s) from this thread on one page
Page 2 of 2 First 12
• 01-26-2000, 12:38 AM
S. Cook
KEA says - "I couldn't agree with you more! I personally believe that two well trained firefighters should be able to handle "ANY" 1 3/4" flow available today, whether its from our nozzle or any other manufacture!"

Why should it take 2 well trained firefighters? One well trained firefighter should handle any 1.75" flow available today - low pressure, high pressure whatever.

If you compared apples to apples with a 200gpm @100psi nozzle (instead of the 150gpm you referenced) with the 200gpm @75psi would you get the same results?

It doesn't take a rocket scientist to see that a 200gpm stream is going to have more mass than a 150gpm.

Do you have any test data to support a 75psi low pressure nozzle having more punch when compared with a higher pressure nozzle at the same flow?

How can you get 12.47 more pounds out of a nozzle than you put into it?
• 01-26-2000, 12:59 PM
KEA
S Cook:
Why should it take 2 well trained firefighters?

It shouldn't!! I agree totally!! The only reason I referenced two is because that is what is a common goal.

If you compared apples to apples with a 200gpm @100psi nozzle (instead of the 150gpm you referenced) with the 200gpm @75psi would you get the same results?

That's the nice thing with physics. If you take a 200 gpm nozzle @75 psi and compare it to a 200 gpm nozzle at @100 psi you will find that the reaction and punch is greater with the 100psi.

My point in my original post on this is to help people realize that the greater pressure only provides the greater punch when you compare the SAME FLOW. All to often people are being told go to low pressure nozzles and you get more flow with less reaction or go to high pressure nozzles to get more punch. Thats not always the case. If you read my post carefully you will find that it was only to share some physic properties that help take the sales pitch out of the equation and help people to make an informed decision when they look at nozzles. Nothing more, nothing less.

Do you have any test data to support a 75psi low pressure nozzle having more punch when compared with a higher pressure nozzle at the same flow?

No and if someone ever proves that then they will win an award becasue they would have established a new law of physics.

You can do the tests on your calculator. Its all based on know physics properties. The term "SAME FLOW" is the key. At the SAME FLOW the higher pressure will have more punch. That's physics. Again, my point was that people shouldn't be fooled to believe that just because a nozzle has a higher pressure means it has a better punch. It has that better punch when flows are equal and may not when flows are less.

How can you get 12.47 more pounds out of a nozzle than you put into it?

I didn't! If you look at the formula to determine reaction force you will see where the numbers come from?

NR=.0505 X quantity X square root of the pressure
NR = .0505 X 200 X square root of 75
NR = 10.10 X 8.66
NR = 87.47

Thanks
Kirk Allen
First Strike Technologies, Inc.
• 01-27-2000, 01:53 AM
LHS
NR=.0505 X quantity X square root of the pressure
NR = .0505 X 200 X square root of 75
NR = 10.10 X 8.66
NR = 87.47

That is a nice formula but it is not accurate on all fog tips or all styles of nozzles.
• 01-27-2000, 01:57 AM
LHS
I think Mr. Cook can verify that 200 gpm at 100 psi nozzle pressure can also have zero pounds reaction. As can 300 gpm at 100 psi. I've seem him let go of a hose line at those flows and the line didn't go anywhere, he was standing, wasn't using ropes, loops, etc, just learned how to hold a fire hose.

Don't let the goofy formulas drive you crazy. Lots of what we do is an art. If you neer figure out the art the hose will kick your tail. The nozzleman has lots to do with reaction.
• 01-27-2000, 06:26 PM
S. Cook
Not to beat a dead horse, but...

I'm visiting with a friend of mine today who happens to be a legit rocket scientist (honest) and I ask him about how 75psi of water going one way can equal 87psi going back the other.

He said he didn't know, because if more pressure were going backwards than forwards from a hole, the water would go backwards up into the hole.
• 01-28-2000, 10:39 AM
KEA
Larry Stevens, Fire Rescue Magazine:

Your correct about the formula not applying to all nozzles. There is a different one for smooth bores. The only reason I posted the formula was to answer S. Cooks question on where the numbers came from.

If the formula is not corrrect as you state am I to assume that Jim Cottrell with TFT was wrong regarding the reaction test compared to the formuala. You may recall the article you ran in Firefighter News about it several years ago. Jim did a fine job presenting the physics that support the formula. I know that he still teaches it in his fire flow classes and even hands out the info on disk. Im sure if you contact him he could provide you with a copy to confirm the formula is accurate.

Im sure you didn't mean to say that the line S Cook was holding had ZERO reaction. We all know that simply is not the case.

Again, you are correct in the fact that hose handling is an art, if not mastered, the hose can make life misserable because of the REACTION.

My post on this subject was not intended to promote or degrade anyone or any nozzle. It was intended to simply be thought provoking and not start an argument with a competitor or its supporters.

S Cook: The answer is simple. There is difference in inch pounds and foot pounds.

Share the Knowledge!
Kirk Allen
First Strike Technologies, Inc.

[This message has been edited by KEA (edited January 28, 2000).]
• 01-28-2000, 11:06 AM
S. Cook
/The answer is simple. There is difference in inch pounds and foot pounds./

I agree - there is a big difference between inch and foot pounds, so maybe I missed something, where/when did we switch from inch pounds to foot pounds? I can't find in referenced anywhere except Capt. Zada's post
• 01-28-2000, 12:20 PM
KEA
S Cook:
Page 5-113 of the NFPA Fire Protection Handbook 17th edition. When expressing measurements it is customary to us "pounds" to represent foot pounds and when a more specific measurement is used you will see "PSI", which is pounds per square inch.

Note the description of each factor used in the formula
NR= Nozzle reaction, LB
NP= Nozzle pressure, PSI

That may be where the confusionn came from.
If you would like to convert PSI to foot pounds simply multiply psi by 144.

Kirk Allen
First Strike Technologies, Inc.
• 01-28-2000, 02:24 PM
S. Cook
So, I gather the the 87 pounds nozzle reaction you posted is foot pounds.

If I'm right, then I can divide that by 144 to get inch pounds = .61psi.

Then dividing 75 pounds nozzle raction(from the 150gpm@100psi nozzle reaction the formula you posted) by 144 I get .52psi

Am I right so far?

If yes - I still have more pressure going backwards than forwards.

If no, where's my mistake?
• 01-28-2000, 07:29 PM
KEA
S. Cook: You lost me on your math. Please post the formula your using and plug the numbers in so that it can be reviewed to better understand the point your trying to make.

/dividing 75 pounds nozzle raction(from the 150gpm@100psi nozzle reaction the formula you posted) by 144 I get .52psi/

That would be .52psi reaction. .52 psi is more than the 100 psi nozzle pressure.

/I still have more pressure going backwards than forwards /

.52-psi is not more than 100 psi.

IF you can prove this wrong you will have disproven one of Newtons laws of physics.

Sorry if I have made this confusing.

Kirk Allen
First Strike Technologies, Inc.

[This message has been edited by KEA (edited January 28, 2000).]
• 01-29-2000, 12:41 AM
S. Cook
Hey, I'm way lost, but I think I've figured it out.

After reading and re-reading all the related posts, it seems that once a drop of water leaves the nozzle, it's force is converted to foot pounds.

Is that a true statement?

If so, then the 75psi nozzle pressure is actually 10,800 foot pounds in the hose that drops to 87 after it exits the nozzle.

I have decided to end all the questions, and confusion (cheers from the crowd)!

In the next few weeks, I will be setting up a test stand and testing all the nozzles I can get my hands on using a digital flow meter and a strain gauge.

I will test and provide actual nozzle reaction vs flow and any other results that I can find.

In the event you want to include the Vindicator I am sending you a shipping address via email.

If Rod or any other mfg wants to send a nozzle for testing, let me know and I'll send you the shipping address. (Elkhart - we're loaded with SM 20 and 30s)
Show 40 post(s) from this thread on one page
Page 2 of 2 First 12