Thread: Nozzle Reaction

  1. #1
    Forum Member

    Join Date
    Apr 2005
    Posts
    70

    Default Nozzle Reaction

    Need some input please. I am seeing our guys and gals having trouble holding our attack lines. We have been training on proper handling and back up but the nozzle reaction still seems to be to much. We are flowing 150 gpm thru 200' of hose with an Elkhart SM20 nozzle with 150 psi discharge pressure.

    I was wondering what flows and nozzles others are using. Any input would be appreciated.

  2. #2
    MembersZone Subscriber
    KevinFFVFD's Avatar
    Join Date
    Jun 2006
    Location
    Vicksburg, Mississippi, USA
    Posts
    573

    Default

    at least 2 people on an 1.5 inch line and at least 3 on a 2.5 inch line, at least thats what we do. you way want to watch the way they are holding their nozzles and work on your back-up guy taking the brunt of the pressure. the guy with the nozzle should only have to aim the nozzel.

  3. #3
    Forum Member
    DeputyChiefGonzo's Avatar
    Join Date
    Aug 2000
    Location
    Somewhere between genius and insanity!
    Posts
    13,586

    Default

    Quote Originally Posted by chiefanthony View Post
    Need some input please. I am seeing our guys and gals having trouble holding our attack lines. We have been training on proper handling and back up but the nozzle reaction still seems to be to much. We are flowing 150 gpm thru 200' of hose with an Elkhart SM20 nozzle with 150 psi discharge pressure.

    I was wondering what flows and nozzles others are using. Any input would be appreciated.
    You want 100 psi at the nozzle for a combo, 50 psi for a solid bore. If yuou have 150 psi at the tip, it's no wonder they are having a hard time.
    ‎"The education of a firefighter and the continued education of a firefighter is what makes "real" firefighters. Continuous skill development is the core of progressive firefighting. We learn by doing and doing it again and again, both on the training ground and the fireground."
    Lt. Ray McCormack, FDNY

  4. #4
    Forum Member

    Join Date
    Apr 2005
    Posts
    70

    Default

    Our test show we are getting right at 100 psi nozzle pressure with the 150 psi discharge pressure flowing 150 gpm.

  5. #5
    Forum Member
    FyredUp's Avatar
    Join Date
    Jul 1999
    Location
    Rural Wisconsin, Retired from the burbs of Milwaukee
    Posts
    10,281

    Default

    chiefanthony...

    If you wish to maintain roughly 150 gpm flow there are options to explore to reduce your nozzle reaction.

    1) See if your automatic nozzles can be modified to operate at 50 or 75 psi.

    2) Try the Elkhart Chief nozzle in the low pressure version. They are available in 150 gpm at either 50 or 74 psi.

    3) Smooth bore tip. 7/8 inch tip flows 160 gpm at 50 psi.

    Although I have to question nozzle and hose handling techniques if 2 people on that line can't control a hose flowing 150 gpm at 100 psi. Perhaps a little review of hose handling techniques using the IFSTA book might be advisable.

    FyredUp
    Last edited by FyredUp; 05-18-2007 at 12:29 PM. Reason: correcting a typo

  6. #6
    MembersZone Subscriber

    Join Date
    Aug 2006
    Location
    Franklin, TN
    Posts
    113

    Default

    NR= 76# for 100psi nozzle @ 150
    NR= 57# for 75psi nozzle @ 150

    A 75 or 80# nozzle reaction can make it hard to advance with two. Maybe add a third or opt for the 75psi nozzle.

  7. #7
    Forum Member

    Join Date
    Jan 2007
    Posts
    1,063

    Default

    In my volly dept. we've had similar trouble. Often alleviated by pairing smaller firefighters with less muscle mass with more substantial firefighters. Little one in front, big one in back.

  8. #8
    MembersZone Subscriber

    Join Date
    Jan 2007
    Location
    Pa Wilds
    Posts
    598

    Default Nozzle Reaction Force Calculations

    For smooth bore nozzles (solid stream) Reaction force is :
    1.5 X diam. X diam. X Nozzle Pressure = LBS of reaction

    So you can reduce the reaction by reducing the nozzle pressure, but you also reduce the reach and the effectiveness of the penetration. Most play pipes are supposed to be operated with a “Stream Straightener” or baffles internal to the nozzle to reduce the twisting moment that gets imparted to a stream as it is forced through a smaller opening. Sorta like the water going down the drain in the shower. The fluid is trying to use up the energy by making the path longer. This tapered area was designed empirically more than 100 years ago and is optimized for the nozzle design (hand lines = 50 psi & master streams at 80 psi. ) In my travels I see many companies that remove the stream straightener and think the nozzle operates just fine. This just proves that a visual judgment on stream quantity or quality is a poor way to determine stream effectiveness.

    When you calculate nozzle flow for SS appliances the formula is:
    29.87 X diam. X diam. X sq. rt. Nozzle Pressure = flow in GPM.
    Let’s assume that you want to estimate reaction for a fog nozzle. You could enter the 100 psi nozzle pressure and the flow rating for the nozzle and then calculate an equivalent solid bore size for that tip.
    A 2 ˝” Akron Turbo-Jet calculates to 0.9149” and a reaction force of 125.5 LBS. It turns out that a combination nozzle at 100 psi generates a reaction that is exactly ˝ the gpm being delivered. So a task force tip at 150 gpm has a kick back of 75 lbs., but that automatic on the ladder tower can generate 1500 gpm or 750 lbs reaction. Are you derating your basket load to 1 firefighter at 250 lbs so you do not over load your 1000 lb max aerial?

    If your nozzle person turns the fog pattern to 90 degrees (a cardinal sin in some locations) the countering forces reduce the reaction to about 70% or about 88 lbs on the 2 ˝” turbo-jet.

    In another forum, I suggested that work load per firefighter be estimated as follows:
    TOG + BA + 20’ hose w/water + nozzle + reaction force = work load
    You can reduce this load by splitting the reaction force, nozzle wt. & hose weight between the number of FF’s assigned to the line. Try to keep the work load under 80 lbs. per man.

    Just an "Old B.S.'er"
    Kuh Shise

  9. #9
    MembersZone Subscriber

    Join Date
    Jan 2007
    Location
    Pa Wilds
    Posts
    598

    Default Master Stream Effective Reach

    I was going to put in something about effective reach. Also an empirically derived calculation from "Hydraulics for Firemen" by Theobald.

    Effective reach = (Nozzle pressure /2) + 45 feet for solid bore master stream devices.

  10. #10
    MembersZone Subscriber

    Join Date
    May 2000
    Location
    SW MO
    Posts
    4,249

    Default

    From what I see on Elkhart's website, the SM 20 is a mid-range (60-200) automatic nozzle. I'll admit, the only automatics I pump are at the tip of our aerials, but here's a thought. I'm sure you guys more accustomed to automatics will correct me if I botch this (and please do, I could use an education if I'm wrong).

    Anyway, to know exactly what you're flowing on an automatic, you've got to have a flow meter. As you hit nozzle pressure, the spring loaded baffle starts opening. Your pump pressure should stay steady as you increase flow at the pump and tip. Once you've hit max flow at the nozzle, your pump pressure starts increasing again.

    What you may be doing is maxing out the flow on the nozzle and giving them too much pressure. If your hose has less friction loss than the "standard" FL in the textbook, 150 psi may be too much for that hose/nozzle set-up.

  11. #11
    Forum Member
    DeputyMarshal's Avatar
    Join Date
    Apr 2005
    Location
    Connecticut, USA
    Posts
    2,638

    Default

    Quote Originally Posted by Catch22 View Post
    Anyway, to know exactly what you're flowing on an automatic, you've got to have a flow meter. As you hit nozzle pressure, the spring loaded baffle starts opening. Your pump pressure should stay steady as you increase flow at the pump and tip. Once you've hit max flow at the nozzle, your pump pressure starts increasing again.
    Not quite. You can easily calculate the flow from the pump pressure and hose length because the nozzle pressure will remain a constant. Once you supply enough pressure from the pump to provide working presure at the nozzle, the nozzle pressure will be maintained by the spring regulated orifice. More pump pressure will increase GPM but the nozzle pressure will remain relatively constant.

    IOW, pump pressure will not remain constant but nozzle pressure will remain constant throughout its rated GPM range. In this case, 150 psi pump pressure sounds about right to deliver 150 GPM at 100psi nozzle pressure. More pump pressure will deliver more GPM and less pump pressure will deliver less GPM all at the same nozzle pressure.
    "Nemo Plus Voluptatis Quam Nos Habant"

    The Code is more what you'd call "guidelines" than actual rules.

  12. #12
    Forum Member

    Join Date
    Apr 2005
    Posts
    70

    Default

    I am also courious as to what GPM flow other departments around the country are flowing on there 1 3/4" handlines.

  13. #13
    Forum Member
    Bones42's Avatar
    Join Date
    Mar 2001
    Location
    Pt. Beach, NJ
    Posts
    10,701

    Default

    1 3/4" lines are 200'. We use Akron Mid-Range Assault Break-apart nozzles. 175gpm @ 75psi. Remove the tip and it's a 7/8" smoothbore.

    I believe our pump pressure is 120psi and we flow 180gpm. A little bit more with the tip removed.

    No calculations, no figures, no theories. We simply put a flow meter on and ran them.
    Last edited by Bones42; 05-18-2007 at 10:43 AM.
    "This thread is being closed as it is off-topic and not related to the fire industry." - Isn't that what the Off Duty forum was for?

  14. #14
    MembersZone Subscriber
    Edward Hartin's Avatar
    Join Date
    Nov 2002
    Location
    Gresham Oregon
    Posts
    97

    Default Nozzle Reaction & Hose Handling

    A number of good observations in this thread regarding the relationship between nozzle pressure and reaction force. For the same flow rate, a higher pressure will result in greater nozzle reaction. Low pressure nozzles (e.g., 75 psi, 50 psi) will have less nozzle reaction for a given flow than one that is designed for a nozzle pressure of 100 psi. However, there are trade offs. On straight stream the difference is not that noticeable. However, low pressure results in larger droplets and a less dense fog pattern, providing reduced cooling efficiency. With automatic nozzles, the difference is even more noticeable at the low end of the flow range (many "50 psi" automatics have an actual nozzle pressure of around 40 psi at the low end of their flow range). Not to say that these nozzles don't work, but it is important to understand the capabilities and limitations of our tools.

    The Elkhart SM-20 comes in several different varieties (with and without pistol grip for example). I have found that in many cases use of the pistol grip makes it more difficult for people to handle nozzle reaction and operate the nozzle correctly as it positions the shutoff and pattern control too close to the body. Try having your nozzle operator put one hand behind the coupling and position the hose between the arm and body and use the other to operate the nozzle. When the nozzle reaction pushes back, the the arm holding the nozzle will move back placing the force on the bones not muscles. The second person on the line should keep the hose straight behind the nozzle operator (if possible) and direct reaction forces into the floor. The specific techniques will vary depending on the working position (kneeling, crouching, standing), but we have found that this approach works well on 1-3/4" lines up to 200 gpm.
    Attached Images Attached Images  
    Ed Hartin, MS, EFO, MIFireE

  15. #15
    MembersZone Subscriber

    Join Date
    Jun 2006
    Location
    Raleigh, NC
    Posts
    7

    Default Nr

    Anyone can correct me if I am wrong. However, if it is a fog nozzle then it should be a constant 100psi at the nozzle. The NR will differ depending on GPM's flowing through the line. There is also an equation to figure the amount of NR for a line. The equation is

    NR = 0.0505 * Q (GPM) * square root of nozzle pressure.

    Yes I know that this will not be a fireground equation. But, it is something that I can use in pre-planning or in your case trying to find out why your firefighters cannot handle the line. Also, someone else briefly mentioned the proper way to back up the nozzle operator. That could also be a factor as to why the line cannot be handled effectively. Hope this helped.

  16. #16
    Forum Member
    Bones42's Avatar
    Join Date
    Mar 2001
    Location
    Pt. Beach, NJ
    Posts
    10,701

    Default

    Anyone can correct me if I am wrong. However, if it is a fog nozzle then it should be a constant 100psi at the nozzle.
    Ok, you are wrong. Partially. Some fog nozzles are designed to be lower pressure nozzles. 100psi, 75psi, 50psi are all the correct NP for nozzles that are designed for that.

    I do believe that all "automatic" nozzles do use 100psi though. Not sure, we got rid of ours a few years ago.
    "This thread is being closed as it is off-topic and not related to the fire industry." - Isn't that what the Off Duty forum was for?

  17. #17
    Forum Member
    DeputyMarshal's Avatar
    Join Date
    Apr 2005
    Location
    Connecticut, USA
    Posts
    2,638

    Default

    Quote Originally Posted by Bones42 View Post
    I do believe that all "automatic" nozzles do use 100psi though. Not sure, we got rid of ours a few years ago.
    100psi is probably the most common but there are "low pressure" automatic nozzles on the market as well. (usually in the 70-80 psi range)
    "Nemo Plus Voluptatis Quam Nos Habant"

    The Code is more what you'd call "guidelines" than actual rules.

  18. #18
    Forum Member

    Join Date
    Jun 2006
    Location
    Foggy California
    Posts
    968

    Default

    The people who said switch to low-pressure fogs are right on. We use 50PSI fogs and even flowing 125-150GPM is pretty damn easy for two people in even decent shape. We flow 150' and 200' 1.75" preconnects both with 50PSI fogs and have neither a problem with fire flow, nor hoseline handling.

    Especially great for agencies with manpower issues...and who these days doesn't have manpower issues?
    My opinions might coincide with someone of importance's POV... I wouldn't know, since I never bothered to ask. My policy is: "Don't ask, don't care."

    IACOJ--West Coast PITA

  19. #19
    MembersZone Subscriber

    Join Date
    Jan 2007
    Location
    Pa Wilds
    Posts
    598

    Default Automatic Nozzles

    Some of the automatic Elkhart nozzles have a wide operating range for pressure that changes from around 90 psi for the lowest flows to about 120 psi on the high end. TFT's hold the pressure from about 95 psi for the low end to 105 psi at 200 gpm. We operate our attack lines (200 ft. 1 3/4") at 180 psi engine pressure, and all FF's are taught to open the line only until they are comfortable with the handling. If they need flows at the max, the line is able to supply 180 gpm with the nozzle fully open.

    If the handling problem is with large lines and large flows, the use of a Rodgers Hose Rope tool can greatly improve the handling and mobility of a 2 1/2" line. For making interior attack, wedging the line into a wall or corner can aid in holding the nozzle when large volumes are required.

    The suggestion to try things out on an engine equipped with a flow meter is right on target. Friction loss in hose varies with the 5th power of the diameter, and higher pressures stretch the hose diameter making lower friction losses. Nozzle flow calculations for solid streams assume a cross section of hose to nozzle area of at least 4 to 1. When the nozzle diameter is greater than 1/2 the hose diameter, the velocity of the water in the hose line begins to add to the water accelerated by the nozzle pressure and you will get more water than calculated using the 30 x d x d x sq. rt. of nozzle pressure.

    We have been using Neidner hose for 15 years, and found it was easier to kink than Ponn Supreme at lower pressures. In fact we stopped teaching the extend the nozzle 3 ft. and swirl technique due to violent whipping with the more flexible hose. Incidentally, the TFT combined with 1 3/4 hose allows the pump operator to select the max GPM applied since the engine pressure will be about what the line can deliver in gpm from 120 psi to 200 psi.

    Selection of 180 psi operating pressure allows the attack engine to supply max rated gpm when incoming relay pressure is 30 psi. Our elevating platform needs 180 psi to deliver 1000 gpm at 50' elevation and a demountable deck gun with 2" tip needs 180 psi when supplied with dual 3" lines, 200 ft. long. Make it as easy on your pump operator as you can. Doing hydraulic equations at 3:00 AM is a sure recipe for disaster.

  20. #20
    MembersZone Subscriber

    Join Date
    May 2000
    Location
    SW MO
    Posts
    4,249

    Default

    I forgot until I saw KuhShise's post about TFT that they have several powerpoints that are pretty good about explaining different nozzles and such.

    http://www.tft.com/newsite/literatur...ibCat=PowerPnt

    There's some pretty good info in there.

  21. #21
    MembersZone Subscriber

    Join Date
    Feb 2006
    Location
    Virginia
    Posts
    37

    Default Thanks!

    Quote Originally Posted by Catch22 View Post
    I forgot until I saw KuhShise's post about TFT that they have several powerpoints that are pretty good about explaining different nozzles and such.

    http://www.tft.com/newsite/literatur...ibCat=PowerPnt

    There's some pretty good info in there.
    Thanks for the link! Good stuff

  22. #22
    MembersZone Subscriber

    Join Date
    May 2000
    Location
    Wheaton IL
    Posts
    1,767

    Default

    I know every one can't get the required manpower but from an old FF book of mine you should have 1 firefighter on the line for every 50 GPM flowing. If you follow this simple guideline moving an attack line is no problem. The nozzleman can focus on putting the fire out while everyone else can worry about moving the line.
    Try it at a drill and see how easy life becomes when you have enough guys on the line.

  23. #23
    MembersZone Subscriber
    ffmedcbk1's Avatar
    Join Date
    Aug 2003
    Location
    Ohio
    Posts
    781

    Default

    after figuring the nozzle reaction calculation remember this....
    THE AVERAGE FF CAN EFFECTIVELY HANDLE 1/2 THERE BODY WEIGHT IN NOZZLE REACTION

    our lines are
    15/16th" sb on 1.75" hose = 68.994 lbs nr
    1 1/8th" sb on 2.5" hose = 122.66 lbs nr

    TFT Auto set to flow 150 gpm on 1.75 (done with flow meter) 61.85 lbs

  24. #24
    MembersZone Subscriber

    Join Date
    Apr 2003
    Posts
    326

    Default

    Quote Originally Posted by ffmedcbk1 View Post
    after figuring the nozzle reaction calculation remember this....
    THE AVERAGE FF CAN EFFECTIVELY HANDLE 1/2 THERE BODY WEIGHT IN NOZZLE REACTION

    our lines are
    15/16th" sb on 1.75" hose = 68.994 lbs nr
    1 1/8th" sb on 2.5" hose = 122.66 lbs nr

    TFT Auto set to flow 150 gpm on 1.75 (done with flow meter) 61.85 lbs

    Actually the 1 1/8 tip at 50 PSI NP provides 99 LBs of reaction force. The 123 LBs is actually the 1 1/4 tip.

  25. #25
    MembersZone Subscriber

    Join Date
    May 2003
    Location
    Penny Lane
    Posts
    390

    Default

    Quote Originally Posted by DeputyMarshal View Post
    Not quite. You can easily calculate the flow from the pump pressure and hose length because the nozzle pressure will remain a constant. Once you supply enough pressure from the pump to provide working presure at the nozzle, the nozzle pressure will be maintained by the spring regulated orifice. More pump pressure will increase GPM but the nozzle pressure will remain relatively constant.
    And this is the fallacy that leaves automatic nozzles as the most common nozzles on the streets today....

    Yes, you are right in theory, but I think that "theory" is what gets us into trouble. Have you ever tried putting a flowmeter on a line with an auto tip? I've seen a 20-30gpm difference in flow just from moving the pattern from straight stream to flush and back to straight stream (flow measured in the straight stream position both times).

    If...and this is a big 'if'...you get a "good" automatic nozzle, verify its proper operation with in-line pressure gauges and flow meters, and then regularly and constantly maintain it, service it and test it - THEN you may have a chance of getting the automatic's "promised" benefits. As somebody else mentioned, it's not so much that the automatic can't perform comparably to a fixed gallonage fog, it's just that the maintenance and upkeep required - and the unreliability - is just absurd in most situations. Especially when you could just screw a smoothbore tip on the end and call it a day...

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. SOP's for Volunteer FD
    By rumlfire in forum Volunteer Forum
    Replies: 14
    Last Post: 08-01-2006, 11:35 PM
  2. What a load! FE Nozzles and hose debate
    By imtxff44 in forum Firefighters Forum
    Replies: 62
    Last Post: 10-20-2003, 01:38 PM
  3. AFFF or FFFP
    By Lallo in forum Firefighters Forum
    Replies: 6
    Last Post: 03-18-2002, 09:34 PM
  4. nozzle reaction, straight stream VS solid stream
    By BIG PAULIE in forum Fireground Tactics
    Replies: 12
    Last Post: 02-02-2002, 12:11 PM
  5. Thermal Imaging SOG's
    By wtfd92 in forum Firefighters Forum
    Replies: 23
    Last Post: 06-27-2001, 09:41 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts

Log in

Click here to log in or register