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Hydraulics
I just felt the need to post a new forum on Hydraulics. I have noticed alot of driver/operators do not know how to calculate friction loss and all that fun stuff. I am a loser and like hydraulics :P. It just bothers me how they expect to pump the truck but yet cant figure out all the friction loss and all that. If anyone wants to learn let me know, I love to teach this stuff.
Replies to This Discussion
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Permalink Reply by Cody W. Nelson on
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I have learned that if you do not practice using the formulas and working with the coefficients, you tend to forget it. I carry a lamenated card in my pocket when I am driving that has FL, NP, NR, etc. It sure helps to just look at somethig instead of having to recall it.
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Permalink Reply by FF Nick on
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I just stick to the basics on friction loss. After the math was beat into my head I just came up with a simple thing I use. I just figure out how much loss there would be in ONE section of hose, then multiply it by how many sections there are.
One 50' section of 1 3/4 has a friction loss of just over 7 psi. So on a 200' preconnect with a fog nozzle, set your PDP at 125psi
For supply line we use 3 inch with 2 1/2 couplings which has a friction loss of 2psi? <--- If I remember right? Not much you can do with supply line though, it is what it is lol unless your in a relay. We also use 5 inch, but you can have 1000 feet of it out and your friction loss is only totalling about 1psi. lol Nothing we'd ever worry about.
It all comes down to basic math. Mostly multiplying with a hint of division. Hell most people I know just have flow calculators anyway.
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Permalink Reply by Tony P on
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I'm like you Nick. I'll stick to the simple "remember what each diameter hose will lose for each length and multiply by the number of lengths" method. Not very scientific, but it does the job.
But Ron? You are correct. I'll go further to say that if a person cannot work out friction loss at all then why are they operating the pump?
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Permalink Reply by Ronald Williams II on
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I love this stuff, and would figure it out pretty quick for everything, but when im teaching those guys i would just be happy with knowing the friction losses from what we use. like our nozzles require 100 psi at the nozzle and at 100 psi they will put out 100 gpm, plus the 200 ft of 1 inch 3/4, which has a friction loss of 15.5 psi per 100 ft. so they should be putting out 131 psi at the pump. Also, 300 ft. of 3 inch w/ 2.5 inch couplings, then wye'd off to 2- 200 ft lines of 1 inch 3/4, and would have a friction loss of 33.4, so at the pump you should be putting out 133 or 134 psi. You do not have to add 10 psi for the wye due to your not flowing over 350 gpm.
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Permalink Reply by Alex on
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Ron, If you have a few minutes i would love for you to help refresh my math, its been 10 yrs since ive had to actually do the written formulas and now i have a d/e test coming up in about 2 weeks. Any help would be greatly appreciated. Thanks
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Permalink Reply by FETC on
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Tony what do you do when you add appliances and/or reduce to different sizes...
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Permalink Reply by Paul Montpetit on
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And of course don't forget elevation...."rules of thumb" are nice for the basics....but...sometimes have to go back and do it the "right" way....LOL....Might have to drill it into some of your "white hats"....More pressure does NOT always mean more water....I asked a Chief one time how much water he wanted in gallonage.....he looked like I hit him in the face......Paul
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Very true, and i work with some lever pullers, thats why i want to refresh myself so that i can be proud of the title of driver/engineer. anyone can drive a rig, but not everyone has the heart and talent to be a proficient d/e, and thats where i want to be so that i can give 100% every day.
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Permalink Reply by Ben Waller on
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The best option is to use apparatus with flow meters. It makes running the pump much easier.
Standardize with low-pressure nozzles (50 PSI) and it simplifies the calculations and reduces 50 PSI from the PDP when you're using combination/fog tips, too.
We did, and the results are that training and operations are simpler, we don't put nearly as much stress on our engines, pumps, and hoses, and we've been able to standardize our operations.
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Permalink Reply by John Crabbe on
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Having a pump chart is one of the best ways to go and takes doing math on scene out of the factor. Just look at what is out, then go to the chart, and set the pressure for the flow. There is enough on scene to worry about than doing math.
When in D/O class, part of my project was to make a pump chart. Since I was a volly at the time, the chart was made for differing scenarios, preconnects, 2 1/2's to a master stream, sprinkler systen, standpipe and so forth. They still use the charts on the rigs today and takes the guess work out of things. I still use such a chart today when I have to drive on my current dept. It is better to sit down and take the time to make out a chart and keep it with you or rig, than to try and figure F/L on scene.
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