Dummies Guide to Hydraulics

[DonSmithnotTMD]

This surely has been poste don here but I can't find it.

Is there an easy to understand hydraulics guide somewhere?

Keep in mind:

1) I suck at math

2) Everything I've read on here makes my head hurt after 5 minutes

[firemonkey311]

Practice practice practice. I had the same problem at first but i would sit at the fire station and have one of the older jakes make up problems for me to figure out.

[GFDLT1]

Flash cards with all of the different friction losses, gpm's, tips sizes and hose sizes worked for me. Repitition and doing problems on a board and then on the pump panel.

[LeatherHed4Life]

although not 100% accurate for the "hydraulics" junkies. I was first taught how to pump a truck like this.

Fog Nozzle 100psi
Master Stream 80 psi
smooth handline 50psi

add 10 psi for every 100ft of handline
add 5psi for everyfloor above the first
pump a standpipe at 150psi
never send more than 100psi to any truck if relay pumping

i think thats about it. practice running multiple lines at multiple pressures without alot of pressure jumps is what makes you proficient. Pay attn to your guys. they will let you know how the line feels

[CALFFBOU]

Would this help?

http://www.firebooks.com/Catalog.asp...&ProdNum=29294

[ffmedcbk1]

What we had done is ran lines off at 200 ft with the various tip, nozzles, and appliances. We then pitot'ed them and used flow meters. Found out FL then in 100 ft incriments. We then made liminated "cheat sheets" and pinstriped the preconnects for the lengths appropriate to the x-lays.

PM me and i'll send what I have.

[jonnyirons2]

10psi per 100 is way too low, maybe if it was a line heading downhill. more like 15-20 for 1.75 inch line.

[lrg500]

The flash card idea worked for me too. I also hate math but the more I studied hydraulics the more it made sense. Too bad I didn't have any firefighters for math teachers in high school. Study Hard, FOREVER!

[clancyxdogg]

This surely has been poste don here but I can't find it.

Is there an easy to understand hydraulics guide somewhere?

Keep in mind:

1) I suck at math

2) Everything I've read on here makes my head hurt after 5 minutes

The Three Rules of the Fire Service--

1) Pump at 150

2) Cook at 325°

3) Beg for forgiveness,don't ask for permission.




------------or------------------

[LeatherHed4Life]

10psi per 100 is way too low, maybe if it was a line heading downhill. more like 15-20 for 1.75 inch line.

it does become exponentially inaccurate the longer the stretch gets over 300ft. for depts using preconnected 200ft 1 3/4 handlines it should be ballpark flowing 95-125gpm. and is more than generous for 2.5in hose.

[JHR1985]

thumb up means more pressure
thumb down means less pressure

[DeltaCreek]

thumb up means more pressure
thumb down means less pressure

The problem with the thumbs up, thumbs down is that it doesn't account for the problem you may be having. KINKS could be cause the pressure drop.

Perhaps you should invest sometime in becoming familiar with the GPM rating of your equipment. I would suggest that you determine what target flow you are trying to achieve at a fire, with a given size line. Once you have figured that out get a smooth bore nozzle, they come in various sizes which governs the GPM rating, and put it on the end of 100' of the hose you are using. Take the pressure up to fifty pounds of nozzle pressure, measured while flowing with a pitot gauge. As an example: A 15/16" tip, we have learned, loses 30 psi in 100' of 1.75" hose. We learn this by flowing water and using a pitot gauge to study it. If we wanted to achieve the same flow with an automatic nozzle, since it operates or is designed to, at 100 psi, we would take the starting figure, 50 or 100, and add 30 to it for every 100', or 15 to it for every 50' of line. The operating figures can all be pre-determined with lines of a known length.


It can also be determined with a reverse stretch. If the working length is known, as an example 100' of 1.75" line filled out with 2.5", simply start adding 50' of line and taking a reading each time after making the throttle increases. Record the numbers. Mark the hose in some fashion, so that the hose numbers are on each end of the hose, and perhaps each side. When the hose is packed into the Engine record each number onto a sheet in it's position. A chart can be made that shows the hose number, the length it is from the nozzle, and the known loss for this distance. Ex: after a stretch the driver looks at the coupling they are attaching to the pumper. On the end of it is a number, they look at the chart taped on the inside of the cabinet door. It shows that hose # 6534 is 250' behind the 100' working length. The pressure should be X. It is as simple as looking of the sheet and throttling the engine up to that pressure. We have had situations where nozzle peolple were screaming for more pressure and have had drivers with the confidence to be able to say, " my pressure is right you have a problem elsewhere." Low and behold, over in the high grass, that was growing around a vacant building, the hose is discovered to have three kinks in it. Standpipes require a guage to be connected to it at the discharging valve, show the valve can be opened to the known operating pressure, and last if you are relaying water, simply ask the driver you are supplying water to what the residual pressure is on the forward unit. Keep it at 20 psi.

[DonSmithnotTMD]

Would this help?

http://www.firebooks.com/Catalog.asp...&ProdNum=29294

yep - I have a couple on order for when I get back and I downloaded an instructional thing.


Thanks for the help guys

[Squad1LT]

10 psi is too low for an 1 3/4 it should be 22-34 psi. the old standard in Illinois was 22 psi per 100' now it is even higher at 34psi.

All you really need to know to run a pump is common sense and the ability to stay calmn under pressure. If you can get it in the ball park you will be fine. After that it is thumb up thumb down. Even if u know all the fancy formulas on a real fireground it still boils down to experience and getting it close. The main concern is being able to get water and maintain water. Know your apparatus and what can go wrong and how to fix it.

The best thing I used to do is to laminate a cheat card that had friction losses on it and diff things like that. so when i did have to figure out a stretch I could reference that and get it close enough. If you use preconnects you should determine what to pump it at and know that.

It is nice to know the science and formulas behind pumping, but you dont really need it on the street.

[appcap1]

Before you can figure what the FL per 100 is you first have to know what your flow is. It is concievale that FL in 100 feet of 1 3/4 could be as low as 10-20 psi provded that the flow is 100-125 gpm range. at the same time it could be 35 psi (170 gpm) up to 50 psi (200 gpm) depending on tip size or flow rate.

The following is true for 200 foot lays of 1 3/4 inch line with a 100 psi automatic fog nozzle. For flows of 150 gpm, 160 gpm and 170 gpm, your flow equals your PDP. In other words, what you pump (pressure) is what you get (flow)

[amandaandtommy]

Ya, that is one of the classes i', taking nowin fire science. Hydraulics for Firefighting edition2.....

[Ha11igan]

If you use Task Force nozzles, they make a handy dandy slide chart that has it all for you.


For a TFT 100psi automatic nozzle attached to 200' 1 3/4'' flowing 95 GPM the pump pressure needed to achieve 100psi nozzle pressure is 128psi.

Flowing 125 GPM the pump pressure is 148psi to achieve 100psi nozzle pressure.


They use the formula:

PDP = NP + FL

NP = nozzle pressure
FL = friction loss
FL = CQ2L (where the 2 is Q square)
C = friction loss coefficient
C for 1.5'' = 24
C for 1.75'' = 15.5
C for 2.5'' = 2
Q = flow rate in hundreds of GPM
L = length of hose in hundreds of feet

You can easily determine how much water you are flowing and at what friction loss with this formula.

I'll use our crosslays for example but I know this setup is VERY common. You can plug in any flow number (divide it by 100 per the formula along with the length of hose.) I'm going to use 115 GPM.

200' 1.75'' with 100psi TFT nozzles

NP = 100, C = 15.5, Q2 = 1.3225, L = 2

PDP = (100psi) + (15.5 x 1.3225 x 2)

PDP = 100psi + 40.9975

PDP = 141 PSI to achieve 115 GPM through 200' of 1.75'' with TFT 100psi nozzle.


So you can also conclude that the friction loss for this setup is 20.5psi per 100'

Pretty easy.

[Rescue101]

Here's an ancient formula,taught to me years ago.Small line FL 30# per hundred.Big hose 15#per hundred. 100Np fog 80Np Master stream 50Np straight bore.Now the hose FL's are high for modern hose but you'll always have plenty of water and it's easy to remember at O'dark thirty.No sliderule or firecalc required. T.C.

[efd1524]

This site worked great for me.

http://www.hydraulics4jakes.com/

You can also find this finger method for 1.75"

[jbrescue]

I know it is extremly short notice..... Does anyone have a hydraulics worksheet that they use for classes? I am doing a class tonight and am looking to not completely recreate the wheel. Just looking for scenarios to give for hydraulic calculation practice. You can email me at jason@jbrescue.com. Thanks.