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Our department has been converting over to 50psi smoothbore nozzles from 100 psi automatic nozzles. We like the flow rates and lower pressures. We're having problems with our hose kinking when turning the tip and at the connection to the crosslay. I have photos of the hose kinked at the crosslay connection with the discharge gauge for that line in view and reading 140 - 150 psi. Is it the hose? Anyone else have any thoughts?
Make sure you have the correct size tips for the shut off. You don't want anything more than half the diameter of the hose......so 1.75" should be a 15/16" tip....and 2.5" should be 1 and 1/8" tip. 20 psi FL for 50' (1.75") and basically....5-10 for 2.5".
You will encounter kinks...thats the downside of smoothbores....someone should constantly move up and down the line looking for kinks.
My suggestion is......unhook the crosslay....and connect it to a regular discharge......then pack it back into the cross lay bed.....or use a dead load of the rear.......take what you need....and hook up to a discharge.
The hose can have a lot to do with it. Some hose brands and types are much more prone to kinking. Check on the Vindicator Nozzle website. There is a link to a PDF of a study done by Montgomery County, MD. The study covers the nozzles and hoses. Very interesting stuff. Also the FDNY evaluation of the Vindicator is on the site. The problem is the best hose is the hardest to get.
All hose kinks, some brands more than others. It kinks no matter what nozzle you are using, and will decrease flow. The difference is that your old automatics adjusted the stream to make the flow that was available reach farther, which hid the problem. VinnieB has good advice for your particular complaint about the crossbeds.
I'll add just a little to that...there should always be one man assigned the duty for that tour to chase the kinks starting at the pump pannel up to the nozzle team. This was a major factor in the death of a brother in Ohio when the hose was kinked and laying in a pile...no one was responsible for that duty. Assign it at Roll call and don't wait to assign it at the fire...it can and will be overlooked.Quote:
Originally Posted by VinnieB
FTM-PTB
Geat point. If you are short handed have the engineer do it up to the door after setting the panel.
Having the correct amount of firefighters assisting with the line helps a lot also. One firefighter with the officer is not enough. If that is the case by you have the second engine assist with the stretch, then after the line is in place and working they can go back and start a back up line.
Good ideas ADSNWFLD,Quote:
Originally Posted by ADSNWFLD
If your department is shorthanded...place this mans duties in the procedures and use it to explain why you need more men on a company in lieu of using the EMS argument for increased staffing. Outlining duties will enable you to show the city council or whomever that you need 4 or 5 men not 2 or 3.
FTM-PTB
Hey Mrs. Know It All--just out of curiousity when was the last fire you were first due at and on the nozzle. You sound like a fire GOD. Beware the Devil is chasing you.
Quote:
Originally Posted by Needtotrain
Huh? :confused:
Welcome back, Trojan Mutt.Quote:
Originally Posted by Needtotrain
Just curious. What difference would it make if you hook the hose up to a crosslay or a side discharge if both are the same diameter?Quote:
Originally Posted by VinnieB
I think what he is trying to get at is that a rear or crosslay preconnect will have a greater tendancy to kink at the connection due to the angle your stretching your line. Whereas a side discharge is more likely to be a straightshot.
Thats the reason our discharges have an elbow so they angle towards the ground...when using crosslays a kink can form where it leaves the bed. That I believe is the issue.Quote:
Originally Posted by Dave1983
FTM-PTB
[QUOTE=VinnieB]Make sure you have the correct size tips for the shut off. You don't want anything more than half the diameter of the hose......so 1.75" should be a 15/16" tip....and 2.5" should be 1 and 1/8" tip. 20 psi FL for 50' (1.75") and basically....5-10 for 2.5". QUOTE]
Just out of curiosity....why???
I've used 1" and even 1 1/8" tips on 1 3/4" hose and haven't noticed severe kinking issues. On 2 1/2" lines 1 1/4" for 320+ gpm works well too. Where can I find the rule about the tip size relative to the hose size and why did it come to exist?
That could be, but I have to admit, Ive never seen a hose kink at that point. I guess if your swivle is old and not greased it could stick in the wrong direction and cause a problem.Quote:
Originally Posted by FFFRED
Quote:
Originally Posted by Dave1983
Just the opposite experiance...Everytime I have done it...(messing around)......gravity alone will force the 10 foot section that comes off the end down causing a kink. Maybe its the hose, I dunno......now I have to go try it again.. :D
Generally speaking the nozzle tip should be half the diameter of the hose or less to ensure a proper stream. If you want the stream to be tight, have punch and go any distance you need to restrict the nozzle orifice or incease nozzle pressure. Increasing the pressure then causes more turbulance and reaction which affects the quality of the stream. I don't see it effecting kinking unless you adjust your pressure down. But 50 psi at the butt is 50 psi regardless of the orifice, though the engine will pump harder to maintain it on a larger tip. Dave Fornells Fire Stream Management Book is an excellant resource on this topic.Quote:
Originally Posted by MG3610
With our 2 inch the slug tip is 1 1/4 inch. We flow around 290 gpm at 40 psi. It works for us.
FyredUp
It is a long time accepted principal for the most effective stream the tip shouldn't be any larger than 1/2 the diameter. The reason for a tip is because one wants reach with the stream....imagine if all you had was the male butt in your hands...how much reach and penetration would you get? Not much.Quote:
Originally Posted by MG3610
Can you get away with a slightly bigger tip...sure. Some Nozzle men in NY if not first or second due carry a 2 1/2 nozzle with a 1 1/2 to 2 1/2 increaser and a 1 1/8th tip. This is so if the Chief calls for a second, third...etc. line no matter what the size they will have a nozzle that works.
If this nozzle is used on a 1 3/4 line...the stream does ok, however remember this is not the first attack line...many times this is a backup line of sorts. And many times it is on the 2 1/2". Does it give the reach and penetration of a 15/16th tip? No...there is a discernable difference in the stream but it is close enough for the situation.
FTM-PTB
Hose kinks when
1) The outside radius of the bend can no longer stretch, and forces the inner radius to collapse.
2) The residual pressure inside of the hose is reduced to a point where it can no longer overcome the exterior pressures.
Most hoses have been designed to provide a standard 32" doorway kink test at 100 psi. Meaning that, if you double a hose through a standard 32" door and pull it through, the hose should not kink.
With the advent of CAFS and LP nozzles, this has become a problem all over the fire service.
CAFS units have hoses that contain 2/3 air, and that air can compress in a bend, creating terrible kink problems.
LP nozzles lack the pressure to keep the hose open with internal pressures.
Several years ago, I had a company claim they made a hose that, at 100 psi, had a 12" bend radius. I told them it was BS, no possible way.
So, they sent me some for test and evaluation, and I played with it.
At 100 psi pressures, I consistantly got 9" bends before it kinked........
OK, so I reduced the pressure to 50 psi, a tough test to pass, but requird because of LP nozzles.
At 50 psi, I got....
12 inches. No joke.
It has odd friction loss too.
At 100 gpm, it measured 12 psi loss per 100'
At 150 gpm, it measured the same 12 psi, not the standard 24.
At 200 gpm, the F/L was around 18, if I remember right.
The friction loss in conjunction with the kink numbers tell me that the hose has tremendous stretch in length as well as diameter.
Its not a new design, the company said it was a NYC or Canadian construction they designed years ago, just never advertised.
Its being sold now, and a video is on the web.
http://www.kidde-fire.com/angusfirepower2.shtml
Also, you indicated that your pressures were 150 psi + at the panel.
1) check your gage for accuracy at the preconnect outlet. Many readings are wrong.
2) Make sure your preconnect outlet has a swivel and is in working order.
3) Make sure the preconnect hose decking has a sufficient cut out to allow full rotation, right to left. If not, cut the deck hole larger.
As far as refering to the Vidicator site, one needs to know that that nozzle is not demostrated with 1 3/4 inch hose, despite what is stenciled on it or is claimed by the salesman.
The hose Vidicator uses for demo is a 2" interior bore size.
As with any nozzle, the more water you supply it with, the more it will flow.
So the lesson here is,
1) If you need more water, use a bigger hose.
2) If you need less kinking, keep the pressures up, or buy a hose made with high stretch properties.
JT