LET’S DO SOME MATH!. Fire Service Hydraulics During this presentation, we are going to explore the how and why of fire service hydraulics. We are going.

LET’S DO SOME MATH!

Fire Service Hydraulics

During this presentation, we are going to explore the how and why of fire service hydraulics.

We are going to start out fairly basic, and with each detail we cover, we will discover why it is important to know this material, and how it affects our performance on the fire ground.

Fire Service HydraulicsSome of this information may not be directly

related to ‘hydraulics,’ but you will see how it ties together.

Whatever happens, don’t be intimidated by the math. We’ll take it one step at time so that it is

completely understandable.For some, this is fairly new territory, and for others,

it will be a good refresher.

Let’s get started.

Fire Service HydraulicsWhy are hydraulics critical?

We want the fire fighter to fight the fire, not the hose line. That is why knowing fire service hydraulics is so critical.

Knowing hydraulics gives the fire engineer important safety information

He needs to know: • what the apparatus discharge

pressures need to be, • how much friction loss will

he have to deal with,• how much water is left

in a hydrant.

Fire Service HydraulicsIt is critical to understand where the numbers come from

when operating an apparatus pump.

Odds are, your fire department has a “rule of thumb” regarding pump pressures for pre-connected hose lines or lines that are used more often. Therefore, you don’t have to remember or try to use these formulas at a fire. Unless the hose lay is different from what you are used to, a “rule of thumb” should work fine.

BE AWARE … If you don’t know these formulas, you will one day need

them because of a different hose lay, and it will happen at the worst possible time.


Let’s go over some definitions

Order of Operations

Co-efficient

Square & Square Root

More to come …


Order of OperationsThis is one of those math rules we have to live

with. It basically states that certain math operations (add, subtract, multiply, divide) will be completed prior to others.

Rule 1: First perform any calculations inside parentheses.

Rule 2: Next perform all multiplications and divisions, working from left to right.

Rule 3: Lastly, perform all additions and subtractions, working from left to right.

Please Excuse My Dear Aunt Sally

#1 Parenthesis#2 Exponents ( sq and cubes)#3 Multiply#4 Divide#5 Add#6 Subtract


Here’s an example

4 + 5 x 6 – 71st is to multiply 5 x 6 = 30

4 + 30 - 72nd is to add 4 + 30 = 34

34 - 7Lastly, subtract 34 – 7 = 27

27 is the answer.


Why is this important?

When calculating friction loss formulas, the order of operation is critical otherwise you will not get the correct answer.

Remember the 6 steps and you can’t go wrong.

Co-efficient

Co-efficient is the resistance of one material passing next to another material.

For example, water passing next to the material inside of a fire hose.

For our purposes, we will define Co-efficient as the resistance to flow of water inside of a hose.


Why is this important for me to know?

With every different size, length and type of fire hose, the amount of resistance to water flow will change. When the resistance of flow changes, the pressure needed at the pump discharge will also change.

Co-efficient

The Coefficient of a fire service hose is expressed with a numerical value.

The higher the numerical value, the higher the coefficient. This means that more energy is required to push the water

through the fire hose.

Square(²) and Square Root (√)

To find the square of a number, simply multiply that number times itself.

Example -- 4² = 16 is the same as 4 x 4 = 16

Or7.07 ² which is 7.07 x 7.07 which equals 50.

FYI- 50 happens to be the nozzle pressure for

hand lines with smooth bore nozzles.


For square root (√) operations, we must determine the two exact numbers, that

when multiplied by each other, equal the number that we already have. (clear as

mud?)

The square root of 64 is 8.8 x 8 = 64. Easy enough.It is written to look like this

√64 = 8


Fortunately for us in the fire service, there are only two main square roots we need to know.

They are 50 and 80:• 50 is the amount of pressure for a hand line with

a smooth bore nozzle• 80 is the amount of pressure for a master stream

device with a smooth bore nozzle


With this information, let’s find the square root ‘√’ of these two nozzle pressures.

1st – smooth bore pressure of a hand line is 50 psi√50 = 7.07

2nd – smooth bore pressure of a master stream device is 80 psi

√80 = 8.94


Let’s try a couple more square root problems with a calculator.

√81 = ?

√36 = ?

√88 = ?

*NOTE* Go to the next slide for some tips on using the Windows calculator.


A couple of tips for using Windows® calculator: With Windows calculator using square roots, enter the number that

you want to find the square root of and then click “sqrt”.

To find a number’s “square” with this calculator: Select ‘View’ ‘Scientific’ Enter the number you would like to square, and then press the “x^2”

key

Note: You will need the decimal equivalent of the fraction part of the tip size to enter into the calculator. The next slide has a table with fraction and decimal equivalents.


To find the decimal equivalent of any fraction, divide the top number by

the bottom number.

Fraction Decimal

1/16” .0625

1/8” .125

1/4” .25

3/8” .375

1/2” .5

5/8” .625

3/4” .75

7/8” .875


Did you get …

√81 = 9

√36 = 6

√88 = 9.380831519646859109131260227

To shorten this a bit we’ll say 9.4


O-KNow, let’s put a couple of the things we’ve learned together.

4 * √49 = ?

Did you get…

4 * √49 = 28?


Let us try another one …

5.5 * 2.5²

Did you get …

5.5 * 2.5² = 34.375

Excellent!


The following formula is the one that

will be used the most.

This little math formula will work with fog nozzles and smooth bore nozzles.

We are going to find Friction Loss using only hoses, no appliances. (example: a gated wye)


Finding Friction Loss

FL = C*Q²*LFL = Friction Loss

C = Friction Loss CoefficientQ² = Flow rate in hundreds of gallons

(flow/100 and then squared)L = Hose length in hundreds of feet

(length/100)


We’ll start off with “C” which is the hose coefficient.

“C” = the resistance to flow of water inside of a hose.

The table on the next slide lists several sizes of fire hoses and their coefficients.

Fire Service HydraulicsYou can print this for future reference

this is slide #27

Hose Size Coefficient¾” redline 1,1001 ½” line 24

1 ¾” line with

1 ½” couplings

15.5

2 ½” 2

3” .8

4” 0.2

5” 0.08


Next is “Q²” which is the flow rate of the water.

Note: Unless you know the flow rate of the nozzle that you are using, you will have to use another formula (which we will discuss later) to find your gallons

per minute. Once this value is known, we have to divide it by 100 and then square the result

Q= (nozzle flow/100) ²


Now, let’s try one. Using an adjustable gallonage fog nozzle with the flow rate set

at 125 gallons per minute.

Divide 125 by 100= 1.25

Then square it, 1.25² = 1.56


“L” = Total feet of hose divided by 100.

Example: 150 feet of any size hose is150 / 100 = 1.5

Note: Hose diameter is not important for this part of the equation.

Also note: Some fire service hydraulic calculations use hose length as 100’ minimums, even if it requires two sections to make a 100’.

We will look at these in more detail later on.


Now let’s put this together.

150 feet of 1-1/2” hose flowing 125 gallons per minute. We know that we need 100 pounds of pressure at the fog nozzle.


FL = C*Q²*L

C=24 (from the hose coefficient table)

Q²=1.56(125 gallons per minute divided by 100 and then squared)

L=1.5(150 feet of hose divided by 100)

Our formula is:

FL=24*1.56*1.5


FL=24*1.56*1.5

Did you get …

FL = 56 ?

Let’s try another one.


FL = C*Q²*L

You are flowing 250 gallons per minute through 2-1/2” line that is 200 feet long.


Did you getFL = 25 ?

Very Good.We know now that we have 25 psi of friction

loss in our hose lay.Remember, we have to have 100 psi at the

nozzle for adequate water flow. With that said, what does our pump discharge

pressure have to be?


Let’s have another formula for that.

EP = NP + FLEP = Engine Pressure (pump discharge pressure)

NP = Nozzle Pressure (which is 100 psi) FL = Friction Loss (which we now know is 10 psi)

EP = 100 + 25Engine Pressure (pump discharge pressure) = 125 psi


Remember, we want the fire fighter to fight the fire, not the hose line. That is why knowing fire

service hydraulics is so critical.


We mentioned about finding flow rates or gallons per minute (GPM).

Before we go any further, the following formula is used for smooth bore nozzles. Depending on the

region and department you are on, you might not use smooth bore nozzles often, but it is important to know how this formula works.

GPM for smoothbore nozzles

The formula used to determine GPM for smoothbore nozzles.

GPM = 29.7 * d² * √NP

Fire Service HydraulicsGPM = 29.7 d² √NP

• 29.7 is a constant• d² = the diameter of the nozzle squared• √NP = square root of the nozzle pressure

– Master stream devices operate at 80 psi therefore the square root will be 8.9

– Handline devices operate at 50 psi therefore the square root will be 7.07

Fire Service HydraulicsWhat is d² when using a 1-1/4 inch

smooth bore tip?

1-1/4²

Or

1.25 * 1.25

(Refer to slides 20 & 21 if you need assistance)

Did you get1.56?

Great!


Finally, the square root (√) of the Nozzle Pressure (NP)

We discussed earlier that the nozzle pressure for a smooth bore master stream device is 80 psi.

So, the square root of 80 is 8.9√80 = 8.9


O-K, let’s put it together.

GPM = 29.7 * d² * √NP

Our example:We are flowing a hand line with a 7/8”

smooth bore nozzle.


O-K, Did you get 160 GPM?

GPM = 29.7 * d² * √NPgpm = 29.7 * .765 * 7.07

gpm 22.7 * 7.07160 gpm

The next slide is very important.


CHEAT! Every Chance You Get!Not on a test, but at a fire.

Use EVERYTHING to your advantage at a fire. The fire does not care!

With that being said,Remember two things:*


*The square root of a smooth bore nozzle on a hand line is 7.07

*The square root of a smooth bore on a master stream device is 8.9

Use the chart with decimal conversions on slide #20.

Develop your own conversion charts that you have easy access to at a fire.

If you do this, you will not be known as a ‘cheater’ but as being clever. Your chief will say, “That engineer knows his stuff”.

Use everything to your advantage.


Let’s try one more GPM formula.

You are flowing water through a master stream device with a 1-3/8” tip.

GPM=29.7 *d² * √NP


O-K, Did you get 499 GPM?

EXCELLENT !

If you have any questions about this stuff don’t hesitate to let me know.I can be reached via e-mail at

[email protected] Please include your phone number on the e-mail

thanks

mailto:[email protected]


Next Step:We have discussed finding friction loss, engine pressure,

and gallons per minute.Let’s put it together.

You are pumping at a commercial structure fire.You have a hand line on the ground with 200 feet of 1-3/4”

hose with a 3/4” smooth bore tip.What is your:

1: GPM2: Friction Loss

3: Engine Pressure


Let’s start with GPM.We have a hand line (7.07) with a 3/4” (.75)

tip.GPM = 29.7 * d² * √NP

GPM = 29.7 * .56 * 7.07


Did you get 118 gallons per minute?Good.

Now we have to find friction loss.FL = C * Q² * L

Fire Service HydraulicsFriction loss

FL = C * Q² * LWe know from the chart on slide 27 that C = 15.5 and the flow is 118

gpm. Don’t forget we divide the flow by 100 and then square it.118 / 100 = 1.18

1.18² = 1.39Q² = 1.39

So far we have FL = 15.5 * 1.39 * LL is the total length of the hose divided by 100

200 / 100 = 2THUSLY,

FL = 15.5 * 1.39 * 2


Did you get 43 pounds of friction loss?

Great!

Now all we need is (EP) Engine Pressure


(EP) Engine Pressure

EP = NP + FLEP = 50 + 43EP = 93 psi


Wonderful.So, our answers are:

1: GPM is 118 gpm2: Friction Loss is 43 psi

3: Engine Pressure is 93 psi


One more …(This part’s almost over)

You are operating your apparatus at a commercial structure fire with 250 feet of 2-1/2 inch hose on

the ground and a 1-1/4” inch nozzle.Find…1: GPM

2: Friction Loss3: Engine Pressure


Here are the formulas you will need:

GPM = 29.7 *d² * √NP

FL = C * Q² * L

EP = NP + FL

Remember…(any flow over 350 gpm is considered a master stream)

Good Luck & Don’t Cheat.Cheat on the Fire Ground!


Did you get:

GPM = 413 gpm

FL = 69 psi

EP = 149

Moving right along …


The next section of fire service hydraulics we are going to cover

deals with everything else. We will discuss:

• nozzle reaction, • friction loss due to appliances• pressure loss or gain due to

elevation.

Nozzle Reaction

Let’s start with Nozzle Reaction.The main purpose for knowing about nozzle reaction is to illustrate the force that pushes

back on the nozzle as water is flowing. If the nozzle is closed there is no nozzle reaction.

Sir Isaac Newton’s laws of physics play a major

role in understanding what we, as engineers, need to know and have to deal with on the fire

ground.

Nozzle Reaction

Newton said:For every action, there is an opposite and equal

reaction.

Have you ever operated an attack line and the engineer had the pressure too high?

You were fighting the nozzle and hose instead of the fire.

This will explain why.

Nozzle Reaction

There are two formulas for calculating nozzle reaction; one for smooth bore and

one for fog nozzles.We’ll talk about smooth bore first.

NR = 1.57 * d² * NPNR = Nozzle Reaction

1.57 is a constant d² is the diameter of the nozzle, squared

NP = nozzle pressure

Nozzle Reaction

If we have a hand line with a 7/8” tip, what will the nozzle reaction be?

NR = 1.57 * d² * NPLet’s start with diameter.

d² = .765We know that because this is a hand line the NP will be 50.

Therefore….NR = 1.57 * .765 * 50

NR = 60 psi(click here refer to slide #20 for fraction to decimal conversion)

Nozzle Reaction

60 psi is how much pressure your firefighter is having to overcome to fight the fire.

Let’s try one moreYou have a 1-1/8” tip operating as a master stream

device. What is the nozzle reaction?

NR = 1.57 * d² * NP

Nozzle Reaction

Did you get 158 psi?Great!

This illustrates how much counterforce your firefighters are having to deal with while

fighting the fire. THIS is why it is important to pump the correct pressures.

One more, and that’s fog nozzles

Nozzle Reaction

The formula for finding nozzle reaction for a fog nozzle is:

NR = 0.0505 * Q * √NPA couple of differences:

In this equation, Q is total flow. It is not flow divided by 100 and squared.

Nozzle Reaction

• The second difference is with fog nozzles we take the square root of the nozzle pressure, NOT square the nozzle pressure as with the smooth bore.

Nozzle Reaction

Let’s try this one.NR = 0.0505 * Q * √NP

Actually, this one is a bit easier because we already know that most fog nozzles operate at 100 psi, therefore the

square root is 10.

If we have a fog nozzle flowing 150 gpm, our formula looks like this.

NR = 0.0505 * 150 * 10(0.0505 is this formula’s constant)

What is the Nozzle Reaction?

Nozzle Reaction

Did you get 75 psi?

Great Job!!

Try one more.

You have a fog nozzle flowing 200 gpm.

Nozzle Reaction

Did you get 101 psi?

The point to this is:If you pump your apparatus correctly, life

will be easier on your firefighter. You will be a hero, not a zero.

Moving right along.

Friction Loss due to AppliancesWhat is an appliance?

An appliance is any fire related device through which water will flow.

• Friction Loss due to appliances in hand lines is typically not factored into the equation.

• As a general rule of thumb, calculate the friction loss of EACH appliance at 10 psi when flow is >350gpm.

• Aerials and Master Streams are 25 psi.

Now, let’s look at a formula we have already worked, and modify it a little bit.

Friction Loss due to Appliances

EP = FL + NPLook familiar?

We are going to add in friction loss from one appliance into this equation.

EP = FL + AFL + NP

*note* for our illustration we are using “AFL” for appliance friction loss. There are many ways to express this equation. We are doing this for clarity only. IFSTA® pumping apparatus handbook chapter 8 has more information on

this topic.

SO …

Friction Loss due to Appliances

EP = FL + AFL + NP

If we have two appliances, example a Siamese and a reducer, AFL will equal 20 psi.

So, all we need to do when creating this equation is add 20 to the friction loss of the hose and to

the nozzle pressure.

Pressure Loss or Gain due to Elevation

• How high is the nozzle above you?• How low is the nozzle below you?

These two questions will need to be answered so that you, the engineer, can supply your firefighters with the correct pressure.


Water column is the amount of pressure exerted by a one foot tall column of water.

A one foot tall column of water exerts .434 psi of pressure.

(not to be confused with weight)Real close to ½ pound.

For ease of calculations, we’ll say for every 1 foot of elevation, we’ll add 1/2 pound of pressure to

our pump. O-K, have you ever tried adding 1/2 pound of

pressure to your pump?

Pressure Loss or Gain due to Elevation

We will call these pressure differences either

+EL or –EL

for elevation gain or loss.

In other words, if your firefighter is operating above your pump on a hill that is approximately 40 feet

high, then you will need to do WHAT?

Add 20 psi to your pump pressure.

This is based on water column pressure.

Elevation Loss

How about this, for every 10 feet of elevation, let’s add 5 psi to our pump pressure.

Each floor of a building =10 ft or 5 psi

Simple Enough …

Elevation Loss

If we have 40 feet of elevation, let’s add that to our equation:

EP = FL + EL + NPSo, we have

• Friction Loss of the hose line• Friction Loss due to elevation

&• Nozzle Pressure.

Elevation Loss

If you have any high rise buildings in your response area, friction loss due to elevation

will definitely need to be Added to your EP. Fire floor -1 * 5 = EL

EL is the same if you are pumping to a

• hose line that is running up the stairs • standpipe that is installed in the building,.


What happens if our fire operation is below grade?

The same 1/2 pound per foot rule still applies, but the difference is we subtract that pressure from

our pump discharge pressure.

IF your fire ground is below the pump, in a small valley, where your apparatus cannot gain access, and it is 40 feet below the pump,

then …


Subtract 20 pounds of pressure from your pump discharge pressure.

EP = FL + NP – EL

Friction Loss of the hose

(plus)

Nozzle Pressure that is required

(minus)

Elevation


We’ve done all of this math.WHY?

The reason:These formulas are the foundation of what we do

as Engineers on a fire truck. While we might not use these formulas at all fires, we need to know where the numbers for the pressures and flows

come from.


As mentioned earlier, nozzles are purchased for a variety of reasons. It can be because of brand loyalty, pattern characteristics, or

price.


All fog nozzles, whether they are adjustable, constant or automatic, will have a flow rating attached to them. Typically, a

certain flow rate at a certain pressure, AT the nozzle. Now to get this flow rate correct, you have to have the correct

pressure at the nozzle which means you have to compensate for Friction Loss.


We have spent some time going over the mathematical formulas for finding friction

loss. Please know that this is IMPORTANT information.

With that being said, let’s cheat.

How is the best way to determine the flow rate of a fog nozzle?


We have pre-fire plans for our buildings. The strategies and tactics are outlined, and we have a good idea of what we’ll do when we get there. Let’s do the same thing for operating our apparatus pump when we get there. Just like pre-fire plans, it will take a little effort.

What we want to do is determine the flow and pressure from a variety of hose line and appliance configurations.

We’ll start by connecting different hose lines and nozzles.


Connect your hose lines in a configuration that you might use someday on a fire.

Somewhere, between the pump and nozzle, install a flow meter. Begin flowing water until the flows are correct

and then write down the Engine Pressure.

Simple Enough.

(No Flow meter? Check with your local water company. Many have flow meters with standard 2-1/2” fire service threads that they will let the fire

department use at no cost.)


Example Chart For Calculating Engine Pressure(You are welcome to use this chart for any of your equipment, or develop your own chart for the

specific needs of your department. You’re only limited by your imagination!)

Hose Length

Hose Diameter

Nozzle Flow Rate

Engine Pressure

Test 1 150’ 1-3/4” adjustable 95 120 psi

Test 2 150’ 1-3/4” adjustable 125 136 psi

Test 3 150’ 1-3/4” automatic 150 152 psi



Test 6 250’ 1-3/4” SB 7/8” 160 129 psi


So far, we have discussed calculations that are based on hose coefficients and appliance friction losses that are,

well, kind of old. With new technology, the friction loss of fire hoses and appliances has decreased through the

last 20 years.

LoneStar Fire Specialties recommends that you conduct your own tests, with the equipment that you actually

carry on your apparatus and develop charts that can and will assist you, as an engineer, on the fire ground. They

are easy to create, although it does take a little bit of effort. We believe that you will find it to be well worth

your time.


Now, let’s look, briefly, at a comparison between hose sizes and what we are capable of flowing

through them.

For our example, we will assume that we are flowing 200 gallons per minute through a 150 feet of hose with a fog nozzle.

What size hose will we need to flow that

amount of water?

( Remember our Friction Loss Formula.)


FL = C * Q² * L

If we use 1-1/2” hose, this is the equation:FL = 24 * 4 * 1.5

Our friction loss is 144 psi !For a total discharge pressure of 244 psi.

If we use 2-1/2” hose, this is the equation:FL = 2 * 4 * 1.5

Our friction loss is 12 psiFor discharge pressure of 112 psi.

See the difference.


Quick Note:NFPA 1911, pump testing, only requires an

apparatus to pump 70% of rated flow at 200 psi.

Flowing too much water through too small of a hose will needlessly overwork the engine.

Fire Service HydraulicsNow, let’s talk about some math that you really do

need on the fire ground.

We have gone through and developed our charts for all of the hoses, nozzles, and appliances that we carry on the fire truck. That stuff will remain

constant.

Question: What do we have on the fire ground that is NOT constant, is dynamic, is always different,

and can change in the middle of a fire?

The Fire Hydrant

Illustration courtesy IFSTA®


In this part of the presentation we’re going to talk about fire hydrants, our source of water.

We don’t want the word ‘critical’ to become overused, however, knowing how much water

you have in your fire hydrant is critical.We are going to look at some more math formulas

to determine how much water is left in a hydrant. It is always good to understand how to get to

the correct answer by using formulas but, during the hands on training day we will show you a

very practical and effective way to determine if your hydrant will support additional flow.


These are the formulas available for the engineer to use to find the amount of

water available in a hydrant

#1 Percentage Method

#2 First Digit Method

#3 Squaring The Lines Method


With all available math formulas for calculating how much water is left in a fire hydrant, all of them require that the

engineer know the static pressure.

If you will remember from the Water Supplies presentation, the difference between static pressure and residual

pressure is that static pressure is water at rest, that is, it is not moving (flowing) into the fire pump.

Fire Service HydraulicsIf water is flowing into the fire pump, then the

residual pressure is what’s left over.

Again, in order to use these formulas, you have to know what the static pressure is. In order to do that, you have to know how to read gauges and

understand what they are telling you. In many cases, you will use water from the booster

tank to begin fire fighting operations, and then as more companies arrive, the engineer will be

able to get a constant water supply.


Since that is the case, how can the engineer know what the static pressure is?

You have to be quick and paying very close attention to your pump panel.

With that, let’s look at the percentage method.

We covered the percentage method in Water Supplies.

We may have mentioned that it is critical to know how much water you have left in a hydrant.

No matter which formula or method you choose to use.

Fire Service HydraulicsA quick note about the order of operations

If any numbers are in parenthesis (), they are to be calculated first. For example:

(6+4) * (2+3) =10 * 5

or(6 + 2²) * (3 + √16)=

(6 + 4) * (3 + 4)=10 * 7

<<<< Onward >>>>


Percentage MethodPercentage drop = (Static – Residual)(100) / StaticExample – One line flowing 200 gpm Static pressure 70 psi Residual pressure 63Percentage drop = (70-63)(100)/70Percentage drop = (7)(100) / 70Percentage drop = 700 / 70Percentage drop = 10% Now what?


Our answer is 10%. By using the chart on the right, we can get very close and estimate how much water is left in the fire hydrant.

According to the chart, with 10% left, we have at least 3 times the amount of water that is currently being used. If we are already flowing 200 gpm, this chart indicates we have at least another 600 gpm available.

% decrease of pumper intake pressure

Additional water available

0-10% 3 times amount of water being delivered

11-15% 2 times amount of water being delivered

16-25% same amount of water being delivered

Over 25% More water MIGHT be available

Fire Service HydraulicsSummary

Fire Service hydraulics are the basis for what we as engineers do. Not only are we responsible for getting our crews to the scene and back safely, but we have to operate the truck correctly when we get there. Use what you have learned.

Give your firefighters a break, don’t make them fight the hose.

When LoneStar Fire Specialties comes to your department, you will see first hand how all of this information can affect your job performance on the fire ground.

Fire Service hydraulics isn’t the most fun you can have, but this we guarantee, during the hands on training,

You will have a blast!We’ll see ya soon!

And again, if you have any questions about this topic or any others, please let me know.

e-mail to [email protected] Please don’t forget to include your phone number.

Thanks and have a GREAT Day !

mailto:[email protected]

LET’S DO SOME MATH!. Fire Service Hydraulics During this presentation, we are going to explore the how and why of fire service hydraulics. We are going.

Documents

hydraulics critical

different hose

hose lay

rule of thumb

certain math operations

preconnected hose lines

math rules

friction loss formulas