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  #1  
Old 10-18-2007, 05:00 PM
Belmont43's Avatar
Belmont43 Belmont43 is offline
 
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Question Friction loss and Hydraulic calculations!!!

Hey Everyone!
Just wondering if there is a easy way to do these calculations can't say i'm great at math and I get frusturated so just wondering if there are any tools or calculators for these formulas. I know how to do them on paper just hate doing them. If you have any tricks or anything would be great thanks.
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  #2  
Old 10-18-2007, 09:41 PM
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FFbeaumont FFbeaumont is offline
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Location: Victoria
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Well there is the "Q" formula but it is not really practical for fireground principles. If you do a search on the topic I am sure you will find some info. But for now you can use this if you want.
Friction loss is always calculated per 100ft of hose.

1 1/2" hose @ 100GPM = 25psi
1 3/4 @ 100GPM = 15psi
1 3/4 @ 150GPM = 30psi
2 1/2 @ 200GPM = 10psi
2 1/2 @ 250GPM = 15psi
3" @ 250GPM = 5psi
3" @ 500GPM = 20psi

Add 5lbs per floor when flowing water to an elevated area, likewise subtract the same if supplying water downhill.

Those are the fireground numbers I use with my Dept, as far as I know this is fairly standard across the board.
Good luck.
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  #3  
Old 10-19-2007, 07:39 AM
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hmckay91 hmckay91 is offline
 
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Thumbs up Friction loss and Hydraulic calculations!!!

Belmont43

Are you looking for easier ways to DO the calculations or are you looking for TRICKS to estimate fireground friction losses and pump discharge pressures without getting out the paper and pen?

In DOing the caluclations, they are already overly simplified for us firefighters. Just bear down, make yourself a list of formulas and coefficients and work through them.

The TRICK we use in my service is, a pre-built "cheat sheet" for formulas, standard friction losses, standard nozzle pressures, and a few other tidbits, that gets laminated and put it in your helmet liner (or mounted on the pump panel ).

We are using numbers similar to FFbeaumont however ours are in LPM and KPa .

If anyone would like a copy PM me and I will send it out from home this weekend sometime.
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Old 11-03-2007, 06:00 PM
Ping007 Ping007 is offline
 
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Friction loss and hydraulic calculations are very important, cheat sheets on the pump panel are the simplest, however at the time of the call it's not the time to be worried about friction loss & calculations. Easiest thing to remember on an emerg. scene is that you need a specific fire flow. If the crews say the fire isn't going out, you need more flow. Quickest 4 ways to help the situation are up discharge pressure, increase hose diameter, decrease hose lenght or change the nozzle. Friction Loss/ Hydraulic Calcutions are great pre-plan, training tools but difficult at go time.
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  #5  
Old 11-04-2007, 06:55 PM
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http://www.cascadefire.com/fire-stre...or-p-1259.html
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  #6  
Old 11-04-2007, 08:12 PM
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FFbeaumont FFbeaumont is offline
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Quote:
Originally Posted by Ping007
Friction loss and hydraulic calculations are very important, cheat sheets on the pump panel are the simplest, however at the time of the call it's not the time to be worried about friction loss & calculations. Easiest thing to remember on an emerg. scene is that you need a specific fire flow. If the crews say the fire isn't going out, you need more flow. Quickest 4 ways to help the situation are up discharge pressure, increase hose diameter, decrease hose lenght or change the nozzle. Friction Loss/ Hydraulic Calcutions are great pre-plan, training tools but difficult at go time.

I agree that fireflow is important but if their are guys on the lines proper pressure is very crucial. As it was mentioned a cheat sheet near the pump panel is a great idea. Most important is get water at a safe pressure when they call for it, fine tune pressure when things are a little more settled.
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  #7  
Old 11-05-2007, 11:22 AM
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hmckay91 hmckay91 is offline
 
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Default A few ramblings

Ping007

Not sure I fully understood (or agree), below a few comments for your consideration.

Quote:
Originally Posted by Ping007
at the time of the call it's not the time to be worried about friction loss & calculations
This is when you have to worry about them, to get the proper discharge pressures, so you can run maximum fireflows, and use your resources and manpower effectively. Rules of Thumb (or a cheat sheet) and simple addition/subtraction are very useful here.

Quote:
Originally Posted by Ping007
Easiest thing to remember on an emerg. scene is that you need a specific fire flow.
I find it easy to remember I need A fireflow to extinguish a fire but without pre-planing how can would I determine THE specific fireflow? How would I know this dumpster needs 40gpm, this bedroom needs 475gpm, and this propane cylinder needs 1500gpm without pre-planing? (Construction, amount and type of material, stage of size of the fire, exposures, etc)

Quote:
Originally Posted by Ping007
If the crews say the fire isn't going out, you need more flow.
OR my crew is not getting the water on the fire, or my crew are not at the seat of the fire, or the nozzle and pattern were not chosen or set properly, or the pump dischage pressure is not set properly, or my fire control strategy is ineffective...

Quote:
Originally Posted by Ping007
Quickest 4 ways to help the situation are up discharge pressure, increase hose diameter, decrease hose lenght or change the nozzle.
Over-pressurisation will not improve the fireflow. Getting the proper discharge pressure for the nozzle/hoseline configuration will get max flow from that configuration.

Quote:
Originally Posted by Ping007
Quickest 4 ways to help the situation are up discharge pressure, increase hose diameter, decrease hose lenght or change the nozzle. Friction Loss/ Hydraulic Calcutions are great pre-plan, training tools but difficult at go time.
This would decrease the friction loss, but it still needs to be the proper discharge pressure for the nozzle/hoseline configuration. What about running a second line if I needed more fireflow?

Quote:
Originally Posted by Ping007
Quickest 4 ways to help the situation are up discharge pressure, increase hose diameter, decrease hose lenght or change the nozzle.
Changing the nozzle for a higher flow capacity model would increase the fireflow.

Quote:
Originally Posted by Ping007
Friction Loss/ Hydraulic Calcutions are great pre-plan, training tools but difficult at go time.
I find with a bit of a memory and very little pre-planing, you have to remember about six or seven things at GO Time.

I memorise that any fog nozzle needs a dischage pressure of 700kpa and head pressure is 10kpa/m differential. I recall that 30m of 38mm hose with a fog nozzle at max flow(475gpm) is 250 kpa, 30m of 65mm hose feeding a gated wye is (assuming 950gpm) is 100kpa. I pre-plan the friction loss of our preconnects (two 38/45 transverse attack lines, one 65mm blitz line, and perhaps one Cisco setup).

These will get me in the proper discharge pressure ballpark for initial Fire Ground Ops, 95% of the time.

Quote:
Originally Posted by FFbeaumont
I agree that fireflow is important but if their are guys on the lines proper pressure is very crucial. As it was mentioned a cheat sheet near the pump panel is a great idea. Most important is get water at a safe pressure when they call for it, fine tune pressure when things are a little more settled.
I am with FFbeaumont here, proper discharge pressure is crucial.
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  #8  
Old 12-17-2009, 11:36 PM
tezza tezza is offline
 
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Quote:
Originally Posted by hmckay91 View Post
Ping007

I memorise that any fog nozzle needs a dischage pressure of 700kpa and head pressure is 10kpa/m differential. I recall that 30m of 38mm hose with a fog nozzle at max flow(475gpm) is 250 kpa, 30m of 65mm hose feeding a gated wye is (assuming 950gpm) is 100kpa. I pre-plan the friction loss of our preconnects (two 38/45 transverse attack lines, one 65mm blitz line, and perhaps one Cisco setup).

.
Thats an interesting combination of units KPa and GPM? We are metric downunder but Im old enough to remember the old units, and 475 gpm in a 38 line doesnt sound right. Ive made up my own metric equations by simply converting the common imperial FL=CLQ2 equations. In metric I get FL(KPa) =1.2 Q squared for a 63 mm line ( Q is in 100 litres) and 10 times that for a 38mm line. ( we only use 38 and 63 mm hose) This is easy to calculate in your head.
eg 700 lpm in a 63 mm line. =7x7 = 49 x1.2 which is really just addding another 20% so 49 +10 is about 60 KPa. if it was 700 lpm in a 38mm line it would be 600 Kpa.
so your example of 475 gpm = 1800 lpm FL =18x18 =324 +20% =390 then x10 for a 38mm =3900KPa .. that would take some pump!
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  #9  
Old 12-21-2009, 08:14 AM
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InstructorG InstructorG is offline
 
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Talking Hydraulic Calculations a Must for Pump Operators

Hi guys,

Just reading the thread, and the quick answer is there is no easy / standard answer. I'm a pump instructor from way back, and with all the different equipment, hose types, nozzles you really need to take a look at your equipment. Below are the basics.

In Ontario, we use metric for the provincial certification, so that is the language I'm going to speak in. Below are quick charts that we use for friction loss in 30 meters (100 feet) of hose. Now, this is just friction loss, we will do some calculations in a bit.



FIREGROUND CONSTANTS

38mm
FLOW RATE FRICTION LOSS
500 L/min 270 kPa
375 L/min 170 kPa
250 L/min 70 kPa
125 L/min 20 kPa

45mm
FLOW RATE FRICTION LOSS
500 L/min 180 kPa
375 L/min 100 kPa
250 L/min 40 kPa
125 L/min 10 kPa


65mm
FLOW RATE FRICTION LOSS
950 L/min 90 kPa
750 L/min 60 kPa
550 L/min 30 kPa
450 L/min 20 kPa


100mm
FLOW RATE FRICTION LOSS/30 m
1000 L/min 10 kPa
2000 L/min 40 kPa
3000 L/min 80 kPa
4000 L/min 150 kPa
5000 L/min 200 kPa
6000 L/min 300 kPa




125mm
FLOW RATE FRICTION LOSS/30 m
1000 L/min 5 kPa
2000 L/min 20 kPa
3000 L/min 40 kPa
4000 L/min 70 kPa
5000 L/min 100 kPa
6000 L/min 150 kPa

150mm
FLOW RATE FRICTION LOSS/30 m
1000 L/min 3 kPa
2000 L/min 10 kPa
3000 L/min 25 kPa
4000 L/min 40 kPa
5000 L/min 60 kPa
6000 L/min 90 kPa

Parallel 65mm Hose Lines
FLOW RATE FRICTION LOSS/30 m
1000 L/min 25 kPa
2000 L/min 100 kPa
3000 L/min 200 kPa
4000 L/min 400 kPa
5000 L/min 600 kPa
6000 L/min -----------


Now for elevation we have to add or subtract 10 kpa per meter. So if the nozzle is 3 meters above the pump, we add 30 kpa. if the nozzle is 3 meters below the pump we subtract 30 kpa.

For elevation in buildings, we add 35 kpa per floor, not including the 1st floor. for example if you are pumping to the 4th floor, we would add (35x3) 105 kpa.

We use a simple formula to calculate pump discharge pressure (PDP).

TFL = Friction Loss (includes all FL in hose and any appliance in the line)
NP = Nozzle Pressure
E = Elevation

PDP = TFL+NP+-E

EG. Your on a pumper flowing 500 l/min from a 38mm hose, 60 meters long up 5 meters and a nozzle that operates at 700 kPa.

FL38mm hose = (270 x 2) = 540 kpa
NP = 700 kPa
E = 50 kPa

PDP = 540+700+50
PDP = 1290 kPa

Therefore you would set the discharge to 1290 kPa.

Now in Ontario we have a section 21 guidance note (6-26) that talks about flow rates for structural firefighting. It is a good reference.

IMPORTANT NOTE: INCREASE IN PRESSURE DOES NOT ALWAYS EQUAL AN INCREASE IN VOLUME.

If you do the correct FL calculations, and they are easy with a bit of practice or a pump chart on the pannel, the flows will be correct. If you use automatic nozzles, the firefighter at the nozzle won't be able to tell the difference between 800 kpa discharge pressure and 1000 kpa. The nozzle automatically maintains its setting at the tip by increasing / reducing volume. The pump operator is the key to delivering the water volume. It is way more important than the old thumb up or down.

Last edited by InstructorG : 12-22-2009 at 06:06 AM. Reason: Automatic Nozzle
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  #10  
Old 12-21-2009, 08:26 AM
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InstructorG InstructorG is offline
 
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Exclamation Pressure vs. Volume

Quote:
Originally Posted by FFbeaumont View Post
I agree that fireflow is important but if their are guys on the lines proper pressure is very crucial. As it was mentioned a cheat sheet near the pump panel is a great idea. Most important is get water at a safe pressure when they call for it, fine tune pressure when things are a little more settled.
Pressure directly relates to volume. You must first know what volume of water you need to flow to set the correct pump discharge pressure.
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