The H-Factor

Why Fitting Equivalent Length Modifiers Work

This was written by a coworker - Steve Downing - for a customer who had to have an answer for the AHJ as to why the equivalent lengths for C100 piping are less than those for C140:

'The fitting equivalent length modifiers were intended to keep the friction loss (Pf) thru a given size fitting as a constant for any given flow regardless of what kind of pipe it is attached to or what the C-factor of that pipe is when calculated with the Hazen- Williams formula.  It is done by altering the fitting length based on the internal diameter and C-factor of the pipe it is attached to.  This is because the loss thru a fitting is not dependant on the type of pipe attached to it or that pipes C-factor, but in fact is a constant based on flow and caused because the water is forced to make a turn.

 

These two modifiers are found detailed in paragraph 22.4.3.1.3.1,  paragraph 22.4.3.2, and paragraph 22.4.3.2.1 of NFPA 13 (2010 Edition) and apply to all fittings except copper and plastic for which different equivalent length tables are provide by the manufactures.

Let's take an example and see how this works.  Let's assume a 1" Tee with 40 gallons running thru it that's attached to a 1" piece of Schedule 40 with an internal diameter of 1.049 and a C-factor of 120.  Based on the equivalent length of 5 feet from table 22.4.3.1.1, the Pf for such a fitting would be 2.3456

Now, let’s make the C-factor be 100 and redo the calculation.  Our 5 foot fitting now becomes 3.568 based on a modifier of .713 from table 22.4.3.2.1.  This results in a Pf of 2.343.  So, the C-factor portion of the modification does in fact hold the Pf's the same for all practical purposes.

Now, let’s return to a C-factor of 120, but make the pipe be Schedule 10, which has an internal diameter of 1.097.  The fitting modifier from paragraph 22.4.3.1.3.1 is 1.243 which makes our 5 foot fitting into a 6.217 foot fitting.  Now plugging that into the 

Hazen-Williams formula results in a Pf of 2.3455.  So again, the Pf remains essentially the same.

Finally, let's use both Schedule 10 and a C-Factor of 100.  The new equivalent length is 4.4329 based on using both modifiers and the Pf is 2.343, which is again essentially the  same.

The very small difference in the second and forth calculation is attributable to the modifier of .713 listed in NFPA 13.  This number should actually be .713698 or .7137 when rounded based on the formula (Cnew / 120)^1.85 power.  If .7137 was used the two resultant Pf's would be 2.3456 and 2.3456 which would bring them in line with the others.

However, even with this discrepancy, the NFPA modifiers do in fact result in essentially the same Pf thru a fitting regardless of what kind of pipe it is attached to or what C-factor it is used with even though the fitting equivalent lengths will appear to vary from that used with Schedule 40 and a C-factor of 120"

AutoCalc - Assigning Fittings to Use for Elbows and Tees

One of the longstanding requests from customers has been to be able to use other than E and T for their Elbows and Tees when they AutoCalc. They may be calcing a CPVC job, so they want to use other fittings that are assigned to CPVC specific products, for example. Or they may use FireLock fittings, and want to use them. Well, V50.08 and V51.08 made that possible!

When setting up your pipe schedule (the Sizing button in the AutoCalc dialog box), notice the columns on the right pertaining to various fittings and a new Alter Ftn Definitions button. It is here that you can now specify the fittings that should be used with each pipe type.

Over in HydraCALC, the fitting selection box (activated by right-clicking in the Fitting column) shows which fittings are currently available for a given pipe diameter. Notice the letters O through R are preset to reference CPVC fittings (below).

Now pick the Alter Ftn Definitions button. Then select the CPVC pipe type from the Pipe Type list. Int he Default row, type in the letters you want to reference for each fitting type (below).

Pick Ok on this dialog box. Then, pick Ok on the Pipe Schedule dialog box and reopen it by pick the Sizing button, as you did to start. If you select CPVC as the pipe type to use for any of the components found in the Sizing screen (Straight Feed Line Pipe, Grid Main Pipe, UG, etc), the corresponding assigned letters will display it the comlumns at right. These fitting letters will be assigned when you AutoCalc the next time.

Creating Pressure Loss Curves in HydraCALC

Say you want to add a loss curve for a new device. Here's what you do:

1. Open HydraCALC
2. Pick the Utility pulldown menu and then pick Alter Pipe/Fittings
3. Go to the bottom of the table and you will see other curves here (all are defined as a Z fitting)
4. In the first open line, pick Z from the first column, then pick Curve from the second
5. In the third column put in a three letter short name. The first needs to be upper case and the next two lower case
6. In the fourth column type in a description of this device (make, model)

7. On the right half of the table you will see columns with diameters from 1/2" to 24". Locate the one corresponding to the size you need and click in it

8. You can now 'draw' the curve by either picking and dragging the six points on the existing straight line or you can type in six values for Pressure (P1, etc) and Flow (Q1, etc). You can also adjust the scale of the curve by changing the flow and pressure increments. Notice the default is in PSI, click this to change it to bar or kPa. Pick the Save button.

This will place an X in the diameter column you were in. Continue for any other sizes you might need. To remove a curve, arrow over to the X you no longer want and pick the Delete button at the top of the screen.

Reusing Pumps in HydraCALC/AutoCalc

Most times, a pump is going to be used for more than one remote area. Both HydraCALC and HydraCAD/AutoCalc use the same pump input screen, and that input can be saved and recalled.

Once you have your pump set up, pick the File pull down and pick Save Graph. Then, later, you can pick Open Graph to recall that saved pump

Calculating With a Pump but No City Supply in HydraCALC

I have gotten two calls on this in the last two days, so that makes it a good blog topic.

What if you have a pump and a tank, but no city supply? This one is simple:

1. End your piping with the reference point PUMP (any name will do, but be consistent)

2. Set up a pump in the Water Source dialog as follows - Connection = PUMP, Inlet = PUMP and Outlet = PUMP

That's all

Deleting an Info Sheet in HydraCALC

From a Customer:

I have a suggestion for your next revision: The info sheet button could have a pull down tab so that a different info sheet can be used.

Quite often I will use the first calc, modify it and do a standpipe calc. The only problem is the info sheet can not be changed. So I have to copy my input and transfer it all over to a new sheet so that I can bring in the right information sheet. Making the info sheet tab a pull down tab that gives us more choices would be very nice.

Answer - When you want to get rid of an info sheet, open it up and pick the File pull down on that info sheet and pick Clear Data/Change Form!

CPVC - Internal Pipe Diameters

Somewhere around 2003 the internal diameters of CPVC pipe changed, based on manufacturer.

Prior to 2003 our database had CPVC dimension published by IPEX Blazemaster  (.884, 1.109, 1.4, 1.602)

 

In 2003 we updated the database to match data published at the time by Tyco, Spears & Harvel (.874, 1.101, 1.394, 1.598)

Looking online today IPEX Blazemaster’s published data matches our new 2003 data.

Our hydraulics data is not automatically updated on your computer, but we do publish new data files for download as they become available. To get the latest in valve and fitting losses along with new and adjusted pipe diameters, check our website regularly. New data files are always found in the Downloads-Data-HydraCALC section of the secure area of our support pages. The What's New page prior to that location always notes the last 12 months of data and program updates.

Using your own logo on Hydraulics cover sheet

A common request is to put your own logo on the hydraulics printout cover sheet. This is pretty easy:

Note: You may have to make any sizing adjustments to your bitmap for it to fit on the cover sheet. You can use a .jpg or .png file too, just rename it to a .BMP extension

1. Copy your bitmap (i.e. ABC_SPRINKLER.BMP) to the \HES\HydraCALC\Ver50\Data\Setup\Reports folder
2. Locate the file named NO_LOGO.DAT file in that folder. This is a generic Cover Sheet. Rename it to the same name as your bitmap, using the .dat extension (i.e. ABC_SPRINKLER.DAT)
3. When you select Print Final in HydraCALC, select your Cover Sheet
   
   

Fast HydraCALC Input

Many of you know this one, but many don't - so I will show it here.

If you are entering input manually one of the fastest ways to do it is to use the ENTER key to copy input from the line above. For example, if you have a line of input that looks like this:

And the next line is the same except it is 1 1/4 diameter, just hit enter under the Nodes and they each will be incremented by one. When you get to the Diameter column, type in 1.25 or press the F2 key to get that. Then hit enter under each of the remaining columns to bring down the value above it.

Some rules:

1. If you do not want to copy what is directly above a particular column, just use the arrow key to go right instead of the Enter.
2. Fittings do not copy down.
3. The copy down only happens into an empty field. If you already have something there, it will not be overwritten.
4. The copy down only works on items directly above. If there is a blank, then no copy down will happen.

NFPA 2007 Hydraulic Printouts

An update to HydraCALC which contains the ability to printout hydraulics conforming to NFPA 2007 is now available for download on our website. As always - when you update your HydraCALC, you must update your HydraVIEW.

Set up your Info Sheet under View->Info Sheet and choose NFPA 2007. Also choose NFPA 2007 when you print it out under the items Info Sheet, Press / Flow Summary and Calculation Sheets. Those screens and the new printouts are below. Please note that the new standard does not give a provsion to include velocity pressure. This means that the 2007 printouts will not be available if you do a velocity calc. This will change if NFPA creates such a provision.

Why Use Input Types?

Sorry for the lack of posting, between the holidays and trying to get a new HydraCAD update out the door, things have been a _bit_ busy.

So - Input Types. Why use them. A bunch of reasons. What do the mean - here you go:

When you right-click on the Input Type column you will see a list of choices. Simply put they mean Line, Main or Riser Nipple along with a designation specifying a Straight feed pipe or a Grid pipe. Others such as AOver, Drop, UG and Riser are self explanatory.

Does it take a long time to put these in? No. Remember that, like most data fields, if you hit enter on a fresh line, the value entered will copy down. Cut and Paste can also be used to speed things up.

1. Using the Input Types gets you the Graphical Pressure Display (GPD) after you calculate your job. A special feature of the GPD - K-Factor Analysis was discussed in an earlier post

2. The use of Input Types is REQUIRED if you plan to do a Velocity Pressure Calc.

3. It makes it easier to change things that are already entered. Say you have riser nipples and grid lines that are both 1.610 diameter. How do you change just the riser nipples to 2.067? Label them as RN-G (or RN-S depending on your situation) and use the Find tool and pick the Replace tab.

Type in 1.610 (or click on that diameter in the data input before selecting the Find tool). Type in 2.067 in the Replace field and pick the Options button.

Now select RN-G and pick Replace All. Voila!

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4. Input types make it very easy to do a Node Diagram. I will discuss this topic in the near future

So - use Input Types! Feel free to ignore the Num Hds field.

K-Factor Analysis

Did you know that V50 HydraCALC has a tool to help you figure out what K-factor is best for your job?

The tool is found in the Graphical Pressure Display (GPD), which can be used on any job that has the Input Type field filled out. Jobs that come over from HydraCALC-Sizer and HydraCAD have already have this field filled out for you.

Calc your job, then pick the GPD. Move your cursor to the E.H. Press field and click on it.

This will bring up the Review and Alter K-Factors screen. Notice the list of K-Factors on the left and the End Head Pressures on the right. This list of Ks comes from the choices found in the right-click menu of the K-Factor field on the Input Screen. You will see a list of all the Ks and what the end head pressure would be if you used them. Some of these will be in red. The red indicates that if you use that K-factor, the end head pressure will be below the minimum and have to be boosted up.

If you select a K-factor you will be asked if you want to convert all the Ks already in the calculation to that new one. Say yes and it will be done for you.

Negative flows in a Loop or Grid

Another quickie, this one posed by a customer -

Why am I getting negative numbers for my flow on part of my loop system?

That is normal in a loop or grid. The negative sign indicates that the flow is in the reverse order of the direction the pipe has been input into the program. In a loop, the water is split and will go both ways around the loop to get to the flowing heads

Have a great weekend!

Switching Decimal and Digit Grouping Symbols for HydraCALC

This one is a bit esoteric for most of you but it is critical to our European customers. HydraCALC will not load the job properly nor print it out if the Decimal and Digit grouping Symbols are not as we expect to find them here in North America. We realize this is an inconvenience and we will try to figure out a way to make it easier in the future.

In the meantime, the Decimal Symbol must be a period (.) and the Digit Grouping Symbol a comma (,) - To change these, go into Control Panel and double-click on the Regional and Language Options. Then pick Customizse and set the Decimal Symbol and Digit Grouping Symbol as mentioned above and as seen below. The other settings do not affect Hydratec software.

Info Sheet Pressure and Flow

And another thing...

Even been filling out an Info Sheet in HydraCALC and get to the part where it is asking for Flow Required and Pressure Required? Wish there was a quicker way to fill those in?

There is!

When at that page in the Info Sheet, pick the View pulldown and pick Calc Summary. This will open up the Calc Summary in Notepad.

You can then highlight  the Flow and copy and paste it to the proper field in the info sheet. Do the same with the Pressure, too.

 

Betcha Didn't Know...

If you hit the F1 thru F12 keys in HydraCALC while in the Diameter column, it will place the nominal diameter assigned to that key into the Dia. slot! That way to can keep typing along, using only the keyboard and no need to reach for the mouse...

F1 = 1                    F7 = 4
F2 = 1 ¼                F8 = 6
F3 = 1 ½                F9 = 8
F4 = 2                    F10 = 10
F5 = 2 ½                F11 = 12
F6 = 3                    F12 = 14

This was added in HydraCALC V50.14 about one year ago.

Darcy - Who?

Darcy-Weisbach. It's a phrase you are probably hearing more and more of. What is it? It is a formula for calculating friction loss just like Hazen-Williams. But whereas Hazen-Williams is used for water in sprinkler pipe, Darcy-Weisbach can be used for any liquid (including water, but NFPA 13 does not permit its use).

Its recent popularity is due to new fluids that have been produced for use in antifreeze systems. In order to calculate these systems you will need to know some things about the fluid being used, specifically the Density and the Viscosity. The Density is in the units of lbs per cubic foot (kg per cubic meter) and the Viscosity is the units of centipoise. These need to be entered in the appropriate spots in the calculation dialog box.

For more information on Darcy-Weisbach vs. Hazen-Williams see a great comparison article from Scott Martorano of The Viking Group in PDF form at: Darcy-Weisbach Article