Any Elkhart nozzle gurus out there?

[MrFreeze]

We're doing some driver's training and we are running into some discrepancy over what the NP is for our nozzles. Got SM-20F automatic nozzles. They are fog nozzles, to be pumped at 100 psi, correct? None of the data sheets say. The little slide chart you get seems like they are figuring 80 psi NP, but they sell a line of "LOW PRESSURE" nozzles that operate at 75. 5 pounds lower, and now it's low pressure? However, they say if you don't have a pressure guide slide chart that you "GO BACK TO THE BASICS" and figure 100#. Is it an 80 pounder, or is it a 100 pounder? Does NFPA 1964 say anything about what NP a certain nozzle will operate at to be compliant? Normally this wouldn't bug the **** out of me, but there will be a test at the end, and no one seems to agree that WE AREN'T FLOWING WHAT WE THINK WE ARE!
Freeze

[E229Lt]

"One for One Hydraulics"
With an SM-20F series nozzle on 200' of 1.75" hose and for flows above 100 GPM, every 1 psi increase of discharge pressure will increase the flow 1 GPM; i.e., to flow 125 GPM, the discharge pressure would have to be 125 psi; to flow 200 GPM, the discharge would have to be 200 psi: One GPM for one psi. What could be easier?

Cut and pasted from: http://www.water-way.net/Product_Gui...ic_nozzles.htm

Looks to me, you'll need 180# at the tip for a good firestream...How's your annual budget look?

[HFDCLanger]

Uhh, LT, I think that was 180 PDP, not NP.

Still another stupid "hydraulics rule". Never trust the "recommended pump discharge pressures" by the nozzle manufacturers. Always try it out for yourself.

[Patrick631]

If there are no #'s stamped on the stem then it is 100-psi nozzle pressure. If you see a number stamped on the stem the low number is the nozzle pressure, and the higher number is the flow.

Patrick

[MrFreeze]

I don't see how the one for one deal works, because it totally ignores the friction loss formulas to even get that water TO THE NOZZLE. No numbers on stem, we have chief nozzles, which do have #'s, but our autos don't. 200' 1.75 preconnects, auto nozzles. No standard flow in writing, but everyone will give you 110# PDP. Some capt's even tell their driver 90#, "to make it easier to move". That seems to be a training issue...
More to come...

[Bones42]

Not Elkharts, but...

We use TFT autos on our 200' 1 3/4" lines. 150gpm at 160psi PDP. Tested and verified.

[MrFreeze]

Bones that is what we had AT MY LAST DEPT. which I ****ing hate saying! And when I bring that up to the guys where I am now, they're all like you can't do that, it's too much pressure to hold. In fact, we used 172# to get our 150, which may have been a little more than 150. But the problem is when I tell anyone that, they all say well you can't hold that crap. The ONLY time I have seen hose training done has been secondary to driver's class, only being used for the operator to figure PDP so yeah STANDING out in a field trying to control that much NR is a pain! BUT THAT AIN'T HOW WE FIGHT FIRE! I can hold 200 gpm by myself in a FIGHTING STANCE down on my knees with the nozzle out in FRONT of me, not tucked into my elbow with the ****ing pistol-grip piece of **** jabbing me in the liver...

And you should have seen there faces when they told me to back the guy on the 3" (we don't have 2 1/2") when I whipped out some FDIC Eng. Co. Ops. class methods, back to the nozzleman, with a rock solid stance. We weren't the ones who almost lost the hose, I know that...

As an aside: Today I came to the house and we have a new rig with a skid unit and pump. What do I see? A ****ing 7/8 POK smoothie! I been trying to explain how easy the **** is, but no one here has used one, and there aren't any small enough to use on any of our handlines...

[MrFreeze]

And maybe somebody can help with this:
I hooked an inline gauge just behind the nozzle, to get a base of the nozzle inlet pressure. It seemed like, with a PDP of 105-110, the nozzle inlet was 75-80. It was just real quick deal; I hadn't set up a chart or anything. Without using an inline flowmeter, how can I use a gauge like I have to get some worthwhile data?

I thought I could: PDP - NInletP = Available Friction Loss

Divide AFL /2 to figure out what the FL is for each 100', and then figure out what GPM flow would amount to that much friction loss, to come up with a GPM figure for a given PDP.

I understand I might be reinventing the wheel, and possibly being anal. But I just don't believe that 110# gives me 100 GPM. I think it gives me 57.something. And no one has shown me any different.

It is a lot like law, where the onus is on the prosecution to prove guilt, not the defense to prove innocence. I gotta spell it out for the set-in-their-ways, otherwise they'll go on thinking they know what is up...

[Bones42]

MrFreeze, we went with a simpler method. How much water in your tank? Figure how many minutes it would take to empty it at 150gpm. Play around with different pump pressures till you get that time. For example, our one tank is 450gals. 3 minutes at 150gpm will empty the tank. We played around with different pressures till we got it to empty in 3 mins. Not exact sciene, but I have a lot of guys that don't buy into formulas and need to actually see it happen to believe it. They have a mindset of "FDNY doesn't do it that way". Of course, none of them ever rode with FDNY, and no one ever asked FDNY, and we aren't FDNY.

Good Luck.

[MrFreeze]

I'll have to do that Sat. Bones. We have 1000 gal. tanks on most of our rigs except for our ladder, which I think is 300. I think I'll just have 'em run their 110# and see if it only takes the expected ten minutes! I bet it is more like fifteen! I too am faced with people who scoff at things like proven formulas and tested figures. These are of course the same people who boil hydraulics down to "crank that sumbitch over til their feet just leave the ground, then back 'er down a turn or two." WTF is wrong with these people? IT'S YOUR ****ING JOB, LEARN IT FOR CHRIST'S SAKE!!!!!!!!!!!!!