Things are busy around here - despite the PE Prep "offseason" beginning, I've been working on improvements and construction of a handful of promising tools.
One basic but very much needed update is an improvement to the Obstruction Calculator. Now, you can enter either the horizontal distance of a sprinkler or the vertical distance of the sprinkler, and get minimum and maximum feedback based on each.
During design, many of us know the depth of the sprinkler and depth of the obstruction prior to determining where (horizontally) the sprinkler is going to be located away from an obstruction. Now the tool helps support that effort.
If you're a Toolkit user, you have immediate access to these updates and can download the latest updates on the dashboard here.
As always, thank you to those who have sent ideas and feedback! Stay tuned for next week on a new database launch for Toolkit users.
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First, a big thank you to those who commented and emailed ideas and topics that contributed to the latest tool for this site - the Trapeze Calculator.
With only a few "knowns" (pipe diameter and schedule, and distances to nearest structure), you can now quickly calculate the section modulus that's required, visit options for the trapeze bar, and see these options schematically in a to-scale detail.
Have multiple pipes on a trapeze? Calculate the section modulus required for each, add the two moduli together, and simply override the Section Modulus Required value below to see your options.
Get CAD Details
Want a CAD version of the detail? Sure thing - the downloadable All-Access Toolkit allows you to save and print these calculations as PDFs, which can then be imported directly into AutoCAD and use the ALIGN function to scale it to your drawing.
Already a Toolkit user? Install the latest version from your dashboard to get the updates to this tool. No new activation code is necessary.
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Thanks for those who have provided feedback thus far - here's the progress on the Trapeze Sizing Tool.
Also, quick note: today is the last day to get the custom mousepad with the Toolkit. If you're an all-access subscriber of the Toolkit (new today or prior), be sure to fill out your information to get a free one on the dashboard. Those will be sent out starting next week.
The tool was not allowing any entry when it initially posted but that's cleaned up now.
I've updated some hanger detailing, labels, and Unistrut sizing.
What else would be helpful to incorporate here? I plan to add some flexibility on structure types, include a graphic scale, and offer options for which trapeze to show (the default is Schedule 10 pipe).
Also, for contractors - what is your preferred method of attachment and hanging for the trapeze? A washer and nut would typically be used for Unistrut and angle iron, but what about pipe as a trapeze? I'd like to detail what is realistic and preferred in the field.
As always, feel free topost comments here or shoot me an email with ideas. Thanks in advance!
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First, a huge thank you to everyone who's expressed interest and purchased the Toolkit - I very much appreciate the fantastic response to the launch over the last three weeks!
It's a short post this week - I've been developing a Trapeze Hanger tool that sizes and schematically details trapeze hangers. This will likely be the first of three posts while developing this tool.
Questions for you at this point in time:
(1) What other possible standard trapeze materials do you use that could be helpful as part of this tool?
(2) What would you like to see shown in the detail?
(3) If the detail could be easily translated to AutoCAD from this calculator, could it be something helpful for your projects? If so, what would you want shown and identified?
Click here to test and comment on the Trapeze Hanger tool, thanks in advance!
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Based on some feedback and good ideas I've been experimenting with graphing fire pump & flow test curves with usable data outputs. Below is the first iteration for drawing a fire pump curve alongside a water supply curve.
Determining ideal fire pump configurations for sprinkler and standpipe systems can be
an important part of optimizing fire suppression design
Here's the help I could really use from you - what else would be included in your ideal pump curve?
Would you prefer this be on a logarithmic x-axis?
Want 175 & 300 psi limit lines shown?
Would you want to see at what height in a building the 175 psi threshold would occur - on this graph?
System demand and hose?
I'm open to any and all ideas - in the end I think it'd be great if this tool was the quickest & best method for summarizing and analyzing fire pump output. Share your ideas in the comments here, thanks in advance!
This week's resource was a fun one to put together.
Frequent Questions about NFPA 13 vs. 13R
I've been asked a handful of times in early project planning phases on whether NFPA 13R would be allowed in lieu of NFPA 13 for a project. In short, the two standards have very different objectives and as a result require very different means.
While those who ask are generally looking for ways to save on construction for the project, the differences are important and worth discussing early in a project.
Designed for Different Purposes
It's important to note that NFPA 13R systems are designed primarily with the intent for life safety (extending the amount of time occupants have to escape a burning building). It's stated purpose is to additional "prevent flashover in the room of fire origin, where sprinklered" (NFPA 13R 2019 1.2.2).
Unlike NFPA 13, NFPA 13R works to make the installation of the sprinkler system more affordable and accessible for residential occupancies by targeting the areas of highest fire risk to life safety with sprinkler systems. Swapping NFPA 13 and NFPA 13R is not simply a one-for-one exchange, as their goals are overall quite different.
Summary of Differences
Here's the summary of differences I use between NFPA 13, 13R, and 13D as a downloadable PDF (at the bottom of this page). References to the building code are to the International Building Code, as it's typically the most prevalent used in the US.
As always, there's far more detail to many of these requirements than can be summarized in two pages - so be sure to use the supplied section references to gather more information on specifics for your project.
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In hindsight it seems silly that early as a designer I didn't take time to understand some of the basic nuances and differences in pipe fittings.
Performance Spec Beginnings
Like a good handful of engineers in the industry, I began early in my design days doing bid/performance specification work - outlining big picture issues and project nuances - while leaving the system layout and detailing to the fire sprinkler contractor. It lends itself to understanding code surprisingly well, but lacks the hands-on experience to understand how systems are actually built.
Understanding Each Component
Why is understanding the fitting components important? When I started laying systems out there's some natural rules that develop due to availability of the materials. If you want a basic, labor efficient, and cost-effective system, then it's imperative to understand what materials are commonly available and cost effective - and materials are considered "special order" (ie: expensive and longer lead-times).
After doing shop drawing/fabrication design, finding ways to create clean designs with commonly available components is a very important part of the design process.
Overview of Components
In today's article I'm covering the basic, traditional threaded pipe fittings.
Likely the most familiar component - an elbow has two openings traditionally 90-degrees apart, with female threads on both ends. Elbows can vary in angles - while the most common are 90-degree and 45-degree, cast-iron fittings also offer a 22-1/2 degree threaded elbow.
The 'turn' on the elbow also can vary, particularly with cast-iron elbows. "Long-turn" elbows have a larger radius and make a more gradual curve, which could have hydraulic benefits should the application justify it.
"Street Elbows", typically available as a malleable-iron fitting, is an elbow with a female thread on one side and a male thread on the other. They can be particularly helpful when an elbow is needed to come directly off a welded branch line without a riser nipple in-between the branch pipe and the elbow. I don't know where "street" elbows get their name, but I like to think it comes from a dark and cloudy past of use in 1920's style gangster street battles.
Reducing Elbows & Tees
Elbows, like tees, come in reducing styles, where one opening is simply a different (reduced) size from the original opening. This is a very helpful and friendly feature with threaded fittings, as there are many different reducing elbow and reducing tee sizes that makes their use with branch lines easy.
Identifying Reducing Fittings
To label the size of a reducing tee or elbow, there's a specific order to the different openings.
A 1 x 1/2 reducing elbow, for instance, emphasizes that the primary opening is 1-inch and the smaller opening is 1/2-inch. While this terminology doesn't matter much for a traditional elbow that can be quickly spun around, it's more important for reducing street elbows and certainly for tees.
Reducing tees are labeled by their primary opening (opening A, above), then the opposite side (B, above), and then the last outlet in-between and perpendicular to the first two (opening C, above). If a branch line goes from 1-1/4" in diameter, to a 1" pipe, while serving a 1/2" threaded sprinkler at the intersection, then this reducing tee would be a 1-1/4" x 1" x 1/2" (A x B x C).
Crosses can be helpful when sprinklers split on either side of a continuous branch line. Crosses also offer a good reminder that just because a cross exists, doesn't mean it exists in the wide variety of combinations that could possibly be necessary.
Ductile iron crosses, for instance, are commonly in three sizes 2 x 2 x 1 x 1, 1-1/2 x 1-1/2 x 1 x 1, and 1-1/4 x 1-1/4 x 1 x 1. Cast iron are generally available in a wider variety, even offering sides C and D below in different sizes. It's important to caution, however, that just being available doesn't mean an item is commonly available as 'off the shelf'.
The naming convention for crosses is the primary side (largest, A above) x opposite side (B, above) x adjacent north side (C, above) x remaining south side (D, above). A cross that connects a 2-inch branch pipe to a 1-1/2-inch branch pipe while also splitting out to serve two 1" armovers would be a 2 x 1-1/2 x 1 x 1 fitting.
Riser Nipples to Avoid Crosses
One trick to avoid semi-custom crosses entirely is to consider using two tees at the intersection. Running a riser nipple from one line to another slightly above it can make use of more common reducing tees and give the designer some flexibility that crosses don't always offer.
Order of Threading
One other item to consider with crosses is the order of threading. It's important not just to select fittings that functionally work for a design, but that can physically be threaded in a sequence that can actually be accomplished in the field.
One classic situation fitters understand all too well that designers don't is the order of threading. Without a union, you can't have two risers connect into the same main drain with threaded fittings. Likewise, without a union, a gridded system can't only use threaded connections.
Why? It's all about the order of installation. Threads can only be accomplished in one circular direction (righty-tighty, lefty-loosey, right?). Because of this, threading one end will lock in pipe without the ability to then rotate the pipe on the other end.
Now introducing the union. Sent by the pipe gods, the union has a female threaded connection on both ends with a swivel disc (for lack of a better term) in-between, that allows rotation between the two female inlets. This swivel ability allows threading to occur on either side of the union without the opposite side needing to turn. As cited in the above examples, unions are used to make closed connected systems threadable.
The more basic counterpart to the union, the coupling connects two male segments by way of two female inlets.
If you ever get this mixed up and happen to order unions instead of couplings - don't worry - you'll get a call from someone in the field who will be 'happy' to straighten things out. At least that was the case for me the first and last time I accidentally swapped the two.
Also known as 'reducers' and 'bell reducers', reducing couplings connect two male threaded segments off different sizes. In the sprinkler industry these are far and away the most popular fitting used to connect a sprinkler to a sprig, drop, or armover.
The actual styles and look can vary, but in basic premise there's two different sized inlets with a hex or another flanged point to attach a wrench and turn the coupling relative to a pipe or sprinkler.
Less common in steel systems than in CPVC systems (where there's many less fitting options), bushings are similar to reducing couplings except that one side is male and the other is female.
One applications I've come across that's made good use of bushings is in a new installation installing upright sprinklers were a future ceiling will be provided. Since a minimum 1-inch outlet is required for sprinklers below a ceiling (NFPA 13-2106 22.214.171.124), the 1-inch outlet can be provided but installed with a bushing that can screw directly into the 1-inch outlet and still accommodate the 1/2-inch thread of a standard upright sprinkler.
Plug & Cap
One of the concepts that prompted this article was a discussion my wife and I had about the differences between plugs and caps (yes, I do think about this stuff all the time). In short, plugs have a male connection while caps have a female. They both generally serve the same purpose - to stop the flow of anything in the pipe network.
I don't come across caps in threaded systems much, primarily because of the availability of reducing fittings that size each component to its need. Caps are common for temporary drops in ceilings to close up a system while waiting for ceilings to be installed. Caps are also used when a branch pipe needs to be extended beyond the last sprinkler to catch a hanger.
Plugs are used quite a bit - at remote auxiliary drains that aren't piped to a discharge location, for three-way valves serving water gauges, or on tees connected to dry sprinklers.
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I've never trimmed a dry valve nor have I tested or drained a system myself. I'll also admit that for longer than I should have I never investigated the details of a dry valve.
Hopefully with today's post if you've been in that same boat there's enough to better understand the basic components of a dry pipe valve.
How Dry Pipe Valves Function
1. The valve is in the closed position (clapper inside the valve is horizontal) and air pressure keeps the clapper closed.
2. A sprinkler activates, releasing air pressure at the sprinkler.
3. Air pressure within the dry pipe system begins to reduce.
4. After sufficient air pressure is reduced, the water pressure below the clapper becomes greater than the pressure above the clapper, and the valve opens upward.
5. Water flows through the opening in the valve, past the clapper, and into the system.
6. After entering through the valve, the water gravitates towards the opening in the system where the air pressure is being released, and discharges through the sprinkler at the fire interface.
The clapper is the interface between the air and the water within a dry pipe valve.
It's purpose is to remain closed when air pressure is sufficient in the system, and open when the air pressure falls.
The surface area of the clapper is disproportionately larger on the air side than the water side - which is intentional. To hold the clapper closed, the force on the clapper must be greater on the air side than the water side. Since force is pressure x area, a larger surface area on the air side means the air can be kept at a much lower pressure and still keep the clapper assembly closed - often to a ratio of 4:1 or 5:1 (allowing 40 psi of air to 120 psi of water pressure, for instance).
The External Reset Knob shown in this model is used in lieu of priming water, which otherwise sits on top of the clapper and helps distribute pressure across the top interface of the clapper.
The Knob incorporated in this dry valve is depressed to "unlatch" an open clapper, allowing it to reset back into its normal, closed position. It is a convenient function where a user doesn't have to open the face of the valve in order to reset it.
Low Body Drain Valve
The low-body drain valve allows the air-side of the valve to be drained completely with the clapper closed. Since the main drain valve is below the clapper, the clapper must be opened for the main drain to be used to drain the system.
Main Drain & Intermediate Chamber
The main drain is used to drain water from the system, and is located below the clapper assembly.
For dry valves, some models permit the main drain to be used to test the waterflow pressure switch without opening the clapper.
In other models, there's an intermediate chamber between the water and air side which is normally dry. When water enters the intermediate chamber after the valve opens, the waterflow pressure switch senses water pressure and activates. In this configuration, there's usually a ball valve that can be used to test the waterflow pressure switch and fill the intermediate chamber without opening the dry valve.
The water supply pressure gauge and the system air pressure gauge are included to monitor the incoming water supply pressure and the system air pressure. These gauges are usually attached to a gauge test valve with a plug that permits removal and cleaning of the gauge orifice.
There are typically two pressure switches on the dry pipe valve assembly. The first is a pressure switch which monitors the air supply. When the air supply on the system drops to a pre-determined level, this pressure switch will typically send a supervisory signal to the fire alarm control panel, allowing an early warning that the dry valve is about to open and flood the system.
The second pressure switch is included to activate when there is water in the intermediate chamber or is flooding the system. This is typically an alarm signal that also activates fire alarm notification in a building.
Supply Shut-Off Valve
This valve is typically separate from the dry pipe valve, but allows the system to be shut off after a fire has been sufficiently suppressed. It also can be closed when a system needs to be isolated, such as for a modification, repair or remodel.
Outside of the dry valve assembly, an air maintenance device allows the incoming air to be regulated to a preset air pressure and for that pressure to be maintained in the system.
In order to supply the air, or in many cases now nitrogen, an air compressor or nitrogen generator are provided to supply pressured air or nitrogen into the system.
While this valve is only one model, many of the components between dry valves are designed similarly. For further reading and detail on dry valves, I'd recommend reading NFSA's Layout, Detail and Calculation of Fire Sprinkler Systems (2nd Edition by Kenneth E. Isman, P.E.) and any product data for a dry valve you're reviewing, installing, or specifying.
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New Backflow Preventer Database
I've started a new database for backflow preventers in a similar way to the popular fire sprinkler database.
Backflow preventers are and have been a mainstay on fire sprinkler systems to protect the public water supply from backsiphonage. They're required by both the International Plumbing Code (608.16.4) and the Uniform Plumbing Code, two popular enforced codes in the US and elsewhere.
The new Backflow Preventer Database is in beta and available to current Sprinkler Database subscribers.
Backflow preventers have a number of different parameters. There's differences in types (double check, double check detector, reduced pressure zone, and reduced pressure detector), materials, listed rating, sizes, connections (flanged, grooved), valve types (outside screw and yolk or OS&Y, non-rising stem or NRS, butterfly valves, or ball valves), orientations (horizontal, vertical, n-pattern, y-pattern, z-pattern), and various certifying agencies (UL, FM, ASSE, CSA, NSF, USC).
Most of my curiosity and the reason for building to the tool was (1) to determine what is actually available on the market today, (2) what are the differences between types and models, and (3) how can I easily access manufacturer websites, product data, CAD details, and Revit families with one-click. That curiosity led to the new Backflow Database.
While it's still in an early beta-testing mode users who are already subscribed to the Sprinkler Database can now access the Backflow Database by logging in.
If you're a Sprinkler Database user, give it a try and let me know what improvements I can make. Right now the database includes Wilkins, Ames, and Febco models. Have a manufacturer you'd like to see? Have ideas for updates? Email me at firstname.lastname@example.org or comment here. Thanks in advance!
Vote on New Tools & See What Else is Coming Soon
Around here we're always in development on new and improved tools to help designers, reviewers, inspectors, installers, and engineers in the fire protection industry.
You can now see, and vote, on upcoming tools that are in development for MeyerFire.com. The "Coming Soon" page is now live under "Tools" on the website header.
Take a look at upcoming tools, rate each, and share ideas that we can work towards on this new area of the website.
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Quick updates for this week - thanks to helpful recent suggestions I've updated the Friction Loss Calculator to include several NFPA 13-provided fittings as well as fluid velocity among various sizes.
With a flow rate and length of pipe, you'll see fluid velocity as it's own column in feet/second. While both NFPA 13 and FM Global do not have any limitations on fluid velocity, it's a good point of reference to reference how quickly a fluid is moving through the pipe.
The brief list of fittings at the bottom allow you to compare friction loss across a number of different assembly sizes, so you can compare runs of pipe or assemblies at various sizes all at the same time.
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Joseph Meyer, PE, is a Fire Protection Engineer in St. Louis, Missouri. See bio on About page.