USE GOOGLE FOR FLOW TESTS & SITE PLANS
I sometimes (maybe often) have to learn things the hard way.
This tip today comes from the “Lessons Learned” file, where it took me two bashings over the head before I had my ‘aha’ moment. Forgive me if this is obvious and you've been doing this for years. Again, I have to learn things the hard way sometimes.
So what is it? What are we talking about? Clearly identifying the location of the water supply.
And the ‘aha’ answer – well it’s really simple and can be really helpful.
On many projects we use a flow test to get an idea of the available water supply. We use the available water supply curve to calculate how much pressure and how much flow we have available that can serve our suppression system (sprinkler, standpipe, etc).
Flow tests carry a whole lot of engineering nuance. A flow test is simply an instantaneous “point in time”. It doesn’t account for demand variations like the time of day, day of the week, or seasonal demand like the lawn irrigation system next door. We’ll save that conversation for another day.
One other key factor that a flow test carries is that it is highly dependent on the location from where the test was run.
DOES THE LOCATION OF A FLOW TEST MATTER?
If we have a large, looped supply, then the location horizontally may not play much of a difference. Say we have an Ordinary Hazard Group 2 sprinkler system and our main outside is a 12-inch looped main. The exact point which we tested isn’t going to affect our system all that much, because we wouldn’t get a lot of pressure loss in a 12-inch looped main when we’re only flowing 550 – 750 gpm.
What if we’re not looped? What if it’s a dead-end 6-inch main instead of a looped 12-inch?
Well, now our horizontal location could be critical. If our flow test is taken immediately adjacent to our building, then we have a high degree of confidence of what the water supply is doing right where we’re going to tap it.
But, if our flow test was actually taken 1,500 ft upstream and we have a dead-end 6-inch supply, then we need to calculate the loss through that entire dead-end supply. That could be a lot of pressure loss!
For example, for a 750 gpm sprinkler system, running friction loss for 1,500 ft of 6-inch pipe would lose 16.3 psi. That would have a major impact on most system designs.
So, suffice to say, it can be important to document exactly where a flow test was taken horizontally.
It also matters, however, in the other plane.
DOES THE ELEVATION OF A FLOW TEST MATTER?
There’s a chance, depending upon the project, that the horizontal location of a flow test may not play much of a factor in the system design.
But the elevation of a flow test?
That will always play a factor.
If our static/residual hydrant (gauge hydrant in the diagram) is actually 30-ft lower in elevation than our project site, that has major implications.
Let’s take a quick example.
We look at results from a flow test showing a static pressure of 60 psi with a residual pressure of 50 psi at 1,200 gpm. If that test was taken at the same elevation as our project (a big large flat open field, for example), then we would expect a pressure gauge at the riser to be somewhere around 58-60 psi when nothing is flowing. The pressure gauge and the original gauge hydrant are very close in elevation.
However, what if that test (those readings) was actually taken down the hill, at an elevation that was actually 30-ft lower than our project site?
We would have a lot less available pressure.
As we go deeper in a system, pressure increases. As we rise up within a system, pressure decreases.
So a riser that is approximately 30-ft above the gauge hydrant would have an expected pressure of around 47 psi (60 psi – 30-ft x 0.433 psi/ft).
That might not sound like much, but in some projects without a fire pump where we are already tight on the hydraulic calculations, this can be a major issue.
AN EASY SOLUTION FOR THIS
I’ve had two major project issues related to bad documentation of exactly where the flow test was taken. Most projects I see have a simple description for where a test was taken. It’s something like “at the corner of McKinley & Brower Streets” or “1000-ft east on Highway D from the flow hydrant”. Sometimes it’s a description like “on Highway T”.
Having an intersection will generally help us narrow down which hydrant was actually used in the test. Usually.
Having a description on the road doesn’t help us narrow down much, unless there’s only one hydrant within a half mile radius.
What is very, very helpful for narrowing down which hydrant was used? GPS coordinates.
USING GOOGLE MAPS
Within google maps, it’s extremely easy to precisely locate any point on earth. You don’t even have to go into Google Earth, like we did in an article to grab elevation here.
To grab any GPS coordinate on Google Maps, just right click and you’re presented at the top with the coordinates. Click on those coordinates to “copy” the coordinates where you can then paste them, as text, anywhere else.
Grabbing coordinates off Google Maps is as easy as right-clicking, then selecting the coordinates.
Now, you can paste them into your flow test report, paste them onto your site plan, your hydraulic calculation report, or anywhere else. You only really need to go four decimal places for the coordinates – anything more and you’re talking about less than an inch – which of course is far too precise for what we need here.
Coordinates can then be pasted into anywhere - flow test reports, plans, hydraulic calculations. Anywhere you need.
If later on, someone needs to verify a hydrant elevation, they can just copy and paste these same coordinates back into Google Earth (to get an elevation), or paste these right back into Google to get the location in Google Maps.
Later, anyone with those coordinates can paste them into Google or Google Earth (here), and find the location and the elevation at which those coordinates were taken. In Google Earth, the bottom-right corner shows the elevation.
Using GPS coordinates for flow tests is extremely easy to do. What’s most important, though, is that by providing the coordinates for where the test was taken, you’re taking out so much ambiguity.
Construction documents are only created for communication. If they don’t clearly communicate, then they’re not serving their purpose.
I’ve only recently reached this ‘aha’ moment, but using the coordinates has already helped on recent projects.
What about those two major project issues? What was up with those?
One was related to a very poor description for where a flow test was taken (a flow test that I received from the city and failed to document well).
The other was a flow test that had been taken a good 1,000 ft upstream on a 6-inch dead-end main.
In either of these cases, had I correctly documented the exact location of the test, or had I received the exact location of the second test – we would have had no issues at all, because we could have accounted for these differences during the design of the project.
Hope this tip helps you avoid some headaches in the future, and that you have a great rest of your week!
Awhile back I wrote a piece on sprinklers in electrical rooms. At the time I was asked relatively frequently about when sprinklers are required or allowed to be omitted in electrical rooms.
I guess intuitively, we recognize that electricity and water don’t mix well. We don’t want to address one problem (fire) by creating a new hazard (electrocution) with water in areas that it doesn’t have to be.
In principle, I personally have just about always provided sprinklers in electrical rooms unless they were specifically requested not to be provided by the owner or AHJ; and in those cases, I followed the code path in the IBC or NFPA 13 accordingly.
It seems as though the premise behind not including sprinklers is when the type of electrical equipment present a relatively low hazard or fuel source, and there is no storage. In that situation, a combination of 2-hour fire-resistance-rated enclosure with approved fire detection (assuming a smoke and/or heat detector here) will mean that a fire within the room will be recognized, and the rest of the building will not be compromised as a result.
Providing pipe within an electrical room isn’t always an easy feat. NFPA 70 tells us that electrical equipment requires dedicated zones, and pipe shouldn’t be run above panels without drip pans or other methods of avoiding drip hazards above electrical equipment.
Now are sprinklers in electrical rooms problematic? Generally not (in my experience).
Can pipe routing be made to avoid electrical equipment? Usually yes. I try to only run one branch line into the room, most often above the door (since no electrical equipment is on the door), and stick pipe only above walking pathways within the room.
Does the code or standards express any concern or guidance on this? Yes, both the IBC and NFPA 13 address the situation.
One line that is included in the IBC specifically says that sprinklers “shall not be omitted from any room merely because it...contains electrical equipment”. To me, that’s a fairly explicit way of suggesting that the presence of electrical equipment alone isn’t a justification for omitting sprinklers. Now there are code allowances and necessary provisions to do so, but the suggestion is not to simply avoid sprinklers just because there is electrical gear.
Despite it being awhile since that article, I have had a few requests to make this one into a flowchart, which I’m happy to present today. A special thank you to Alex Riley, PE, who contributed to the code research for this flowchart.
Introduction to Grooved Pipe & Fittings
We previously have introduced different types and combinations of threaded fittings - which have been around for more than a century.
Here we're introducing another common way to join pipe; using grooved fittings.
An attic sprinkler system using a grooved elbow with couplings.
Use of "mechanical" couplings that could allow faster joining of pipe came to life in 1919 by Lieutenant Ernest Tribe. Just a few years later the Victory Pipe Joint Company renamed itself to Victaulic (a combination of "victory" and "hydraulic"), and grew to expand the technology worldwide.
Today, Victaulic and other manufacturing leaders provide grooved fittings that are often used for pipes in fire sprinkler systems. It is not uncommon for both mains and branch lines to be grooved today.
What are common grooved fittings, and how do they work? Let's introduce them.
An in-rack sprinkler with a branch line using (starting with the sprinkler) a groove x thread reducing elbow
with a grooved coupling, a grooved piece of pipe, and a grooved tee (connection not shown).
Let's start with the pipe. In order to give grooved fittings an opportunity to "grip" the pipe and remain in place, they need an opportunity to resist the pressure of the water that is trying to "pull away" the pipe from the fittings which join them together.
A grooved coupling about to connect two grooved-end pipes. Note the loose nut and bolt on the right-hand side, allowing the coupling to be expanded and "slip" over the pipe on the left.
In order to create a groove in the pipe, steel can either be "roll groove" or "cut groove". Roll groove pipe involves pressing an indentation into the pipe near the end of the pipe. This allows a grooved fitting to slip over the end of the pipe and fit into the groove. Roll groove pipe has the advantage of not reducing the pipe thickness, so it can have more tolerance for corrosion than thinner pipe, similar pipe with threads, or pipe with cut grooves.
Pipe which is cut groove involves cutting into the pipe rather than pressing it. This cutting removes a portion of the pipe wall, making a thinner but smooth interior pipe wall. This thinner wall makes it more susceptible to corrosion, however, for pipe systems with a minor slope, the smooth inside of the pipe does not create a ridge where water can sit and corrode the pipe.
Roll Grooved Pipe (top) and Cut Grooved Pipe (bottom). Note the ridge on the inside of the pipe wall for roll groove pipe, and the thinner pipe wall along the cut groove pipe.
A tape measure with a "go" or "no-go" measurement to determine if the groove is within manufacturer tolerances.
ELBOWS & TEES
Let's start with the basics. Elbows allow bends of 90-degrees (most common), 45-degrees, 22-1/2 degrees, and 11-1/4 degrees.
Why not every possible angle? What if I need to have a 60-degree bend because of my building?
First, it wouldn't be economical to make a fitting of every bend. Second, is that using just two 90-degree elbows back-to-back we're able to create a "swing joint" and make any angle we could want, just by changing the elevation of the pipe that's being joined.
Victaulic "FireLock" Grooved Fittings;
90-Degree Elbow #001 (left), 45-Degree Elbow #003 (center), and Standard Tee #002 (right)
One notable specialty with the grooved elbow is a "Drain Elbow", which has the elbow except it includes a drain outlet at the bend of the elbow. This is used all the time with fire department connections which come down a wall and need to be capable of being drained (to avoid having water-charged pipe freeze and burst). This is also called a "Drain-El" or is a Victaulic #10-DR.
A wall-mounted fire department connection that is away from the riser, here showing the "Drain Elbow" with a ball drip below. The portion upstream of the check valve is intended to be dry unless the FDC is actively being used in order to avoid freezing water inside.
Nice sketches, Joe, but that's not how things look in the field!
That's because unlike threaded fittings, the actual pipe joining is by a grooved coupling. The coupling has malleable iron bumps that grip the indent of one groove (pipe/fitting) and connect it to the second groove (the other pipe/fitting).
A grooved coupling (here a Victaulic #009N shown).
There are a host of other fitting types. Grooved Reducing Tees? Yep. Less common. Less common can equate to more expensive, or at least that's what I hear from contractors familiar with all the pricing nuances.
What other grooved fittings do I often see?
Reducing fittings, which is a concentric, single-cast piece of metal that has a large groove on one end and tapers down to a smaller groove on another end. One note of caution is using these in the vertical orientation; I've heard it is much better, more stable, and stronger to use a reducing-fitting as opposed to a reducing-coupling when in a vertical orientation. One of my clients goes so far to say to not use reducing couplings at all (where the coupling itself has two different groove sizes). I wouldn't have the expertise to gauge that myself.
A flange x groove reducer (left) and a grooved cap (right).
There are also reducing adapters, than can accept a flange connection and convert it to a reduced groove connection.
Crosses are also available, as are caps (like the Victaulic #006 shown above on the right) which can terminate the end of a branch line. These caps even have 1-inch threaded opening options for easy auxiliary drains.
Many manufacturers have equipment and components with grooved ends that can readily attach to pipe and fittings.
If you're looking to explore the extend of all available grooved fittings, I'd invite you to check out manufacturer's catalogs or do a simple google search for grooved sprinkler pipe fittings. The manufacturer's product data can do a whole lot of good in clarifying what's been created and listed for use in sprinkler systems.
Have tips, tricks, or things to consider about grooved fittings? Comment below.
That's all for this week - hope you have a great rest of yours.
This week I'm happy to debut an update to one of our popular tools, the K-Factor selector, which is a part of the Toolkit.
This tool quickly calculates the actual pressure and flow across different types of sprinklers. It's helpful when we're trying to select the best-possible sprinkler for a hazard.
Even for light hazard areas, a standard k5.6 sprinkler may not be the 'optimal' sprinkler, from a hydraulic perspective. We touched on this when looking at whether the flow through a sprinkler is governed by the density and area or by the k-factor and minimum pressure.
In short, the minimum flow through a sprinkler can be driven by the coverage area of the sprinkler multiplied by the density of the hazard, or, it can be driven by the k-factor of the sprinkler and the minimum pressure that sprinkler requires.
In either case, it's important to make a quality selection for the k-factor if we want to reduce the required pressure and flow that a system will demand. Less flow usually means less friction loss, which can result in more efficient systems and smaller pipe sizes (saved cost of material and labor).
The updates to this tool make it mobile and tablet friendly, and also now clearly indicate what the 'optimal' sprinkler k-factor is for flow and for pressure (hint: they're not always the same). If you're a Toolkit user, just click the image above to see the updates. Thanks!
A Remote Area Cheatsheet in Metric [PDF]
Last week we debuted a remote area cheatsheet detailing some tips for quick-response reduction, slope adjustments, and dry, double-interlock pre-action and storage area adjustments.
We're all about bringing fire protection pros around the world together (globally), and so today I'm happy to also add a metric version of this same cheatsheet. We plan do to updates like this with our content going forward.
To download, just click below. If you're a University user, you can get all of our latest cheatsheets, checklists and summaries under your University Dashboard. Thanks & have a great week!
This Remote Area cheatsheet allows for quick adjustments to the remote area and minimum remote-area widths when conducting or reviewing fire sprinkler hydraulic calculations.
A New Remote-Area Cheatsheet [PDF]
It's been too long since our last cheatsheet! Happy to bring about a new one to the table today.
One number that I seem to always need to crunch when laying out or reviewing fire sprinkler systems is the remote area adjustments, and the minimum width of a remote area. This applies specifically to the Density/Area method of Hydraulic Calculations in NFPA 13.
The formula is simple enough, w = 1.2 x sqrt(remote area size), where w is the minimum remote area width, and the remote area size is our final adjusted remote area that we're using.
Now for a routine calculation with a remote area of 1,500 sqft, I pretty much have the 46.5-foot area width memorized. Why is it important? The minimum width dimension tells us how wide our remote area needs to be. It's the dimension parallel to the branch lines, that captures as many sprinklers as it can along the branch line.
We take this minimum area, see how many sprinklers this area covers, and round up to the next whole sprinkler. It's our minimum width dimension that we're not allowed to reduce.
The 46.5-foot dimension might be easy enough to remember, but what about when a remote area is reduced using the quick-response reduction? What if the ceiling is also sloped?
Adjustments to the remote area are a process on their own, and each have implications for the minimum remote area width.
If you're using our Toolkit you already know we have tools that will compound the calculations for you. Our Quick-Response Reduction tool will adjust the remote area size based on the ceiling height, and our System Estimator tool will adjust for quick-response, sloped ceilings, dry and pre-action systems, high-temperature sprinklers, and more:
But, there are still times where I just want to quickly glance at my remote area size and translate that into a minimum width. That's what today's cheatsheet is all about.
This quick reference PDF helps address a few things:
I hope this one is helpful for you as conduct or review hydraulic calculations on your projects. Any tips, feedback or improvement ideas, be sure to let me know.
Thanks & have a great rest of your week!
An Updated NFPA 13R & 13D Impact Cheatsheet
We've had an extremely busy fall thus far. We had a soft-rollout of the MeyerFire University platform, which has had very positive feedback and is already over 100 users strong (just a few weeks in)!
If you're interested in learning more, email me at firstname.lastname@example.org and I'd be happy to share more detail or set up a quick demo for your team.
UPDATED NFPA 13R/13D CODE IMPACT CHEETSHEET
A couple of years ago I wrote a couple pieces on when NFPA 13R can be used, and I put together a cheatsheet on the code impacts associated with using NFPA 13R and 13D.
I'm happy to say that we've now updated the cheatsheet with impacts from the 2021 Edition of the IBC. While it may not yet be the adopted building code for your area, it's still important to compare code impacts with the latest version of the building code, so that you're not building a structure today that is already beneath modern building code standards.
Click below to get a copy of the updated cheatsheet:
Thanks & have a great rest of your week!
What is a Coefficient of Discharge?
I have a little different spin on things this week that I'm excited to share.
Last month I wrote a bit about flow coming from hydrants and included PDF flow charts relating the measured pitot pressure to the estimated flow coming from the orifice.
But what is a Coefficient of Discharge?
Check out this new video below - it is a sample from our MeyerFire University platform that we're creating for later this fall. If you don't see the video, click here.
This is all new format for this site, so I'm eager to hear what you think. Comment below or shoot me an email at email@example.com.
Thanks and have a great rest of your week!
Drainage from a fire sprinkler system can often be overlooked as it does not directly fight the fire. However, those involved in inspections & testing of sprinkler systems know all too much about how poor drain design for a sprinkler system can negatively impact how tests are conducted, how long it takes a system to drain, and what messes building owners have to deal with.
Here are various components for drains on a sprinkler system, and some of the common requirements that pair with them.
For best viewing of the table below, click here: requirements-for-drains-in-fire-sprinkler-systems.html
Most of my articles don't necessarily break new ground - and that's intentional. There are a lot of people smarter than myself who volunteer for many years to contribute to the codes and standards we have today.
My role, as I've seen it for some time, is helping share lessons learned and my understanding of those topics. When we share our knowledge, we all help create a world a little more safe from fire.
After writing off and on for five years now (woah!), I finally have something that might be a new contribution to the industry. Not in a real or tangible way, but something that may just not have been thought about exactly like this before. I've asked around and I haven't seen this concept out in the world before, so I think this could be something new.
It could also have very well been thought about and published 30 years ago and just got buried in history. If so, I'll disclaim credit.
My father in-law is a mechanical engineer in research and product development, and for years he's help spur ideas and help kick around new things to try. He once said (perhaps jokingly) that to really make a dent in the world you have to name some kind of industry contribution after yourself.
Well, today's the day. I'm calling this concept the Meyer Box.
I know, I know. This is so profound and earth-shattering. I'm so glad I've come up with such a great name for what could be my only real new-ground breakthrough to date.
Also, if there aren't enough things named Meyer-something around here, I felt it my duty to throw yet another thing into the mix. So if you were itching for more Meyer, then my friend today is your day.
The concept started with the way we lay out smoke detectors. We're allowed to space smoke detectors 30-feet apart, or, as an alternative, any location as long as all points within a room are within 21-feet. I wrote an article about this (often-overlooked) method some time ago.
Sprinkler spacing follows similar logic; except there is an allowable coverage area, per sprinkler, and a maximum spacing that sprinklers can be apart.
Why isn't there some shape for a sprinkler, that if all floor areas are covered in it, that protection is appropriate?
Like all my typical daydreaming, I immediately was forced to spend the rest of the billable hours that day jumping further and further down a wormhole of algebra and confusion.
If you've ever worked with an architect on a sprinkler layout, you know they love to draw circles around sprinklers and spot-the-dot in a very crude way. Is it accurate? No. Does it meet code? No. Does it get them where they need to go? Not really, but they seem to think so.
If a circle doesn't work, there's got to be some natural geometric relationship (a shape) that would work.
That's when I got to experimenting and back to some basic math.
Light Hazard rules are basic, and they result in a basic shape. Non-combustible (or combustible unobstructed) standard spray upright & pendent sprinklers get 225 sqft per sprinkler, and a maximum spacing of 15-feet according to NFPA 13.
First, I drew a sprinkler (above). Next, I copied the sprinkler to the maximum spacing for Light Hazard, 15-feet to the right:
What is the maximum distance these two sprinklers can be copied vertically and not be overspaced? For Light Hazard, that's easy - 15-feet. The 15-ft x 15-ft spacing is exactly 225 sqft total, which is right at the maximum spacing per sprinkler:
Now, if we attribute sprinkler coverage to each of these sprinklers, the dividing line would simply be the midpoint between each sprinkler, effectively creating just a 15-ft x 15-ft box around each sprinkler.
For light hazard, this "box" is easily understood, and is basic. Things get more interesting when our coverage area is limited to 130 square feet per sprinkler, like we often see for Ordinary Hazard.
Using the same approach, let's start with a single sprinkler, ad then copy to a maximum spacing of 15-feet to the right:
Now, in order to not exceed 130 square feet per sprinkler, what is the maximum these two sprinklers can be spaced in the opposite direction? That would be 130 sqft / 15-feet, or 8.67-feet to the north:
Now for the sake of trying to attribute an area to each sprinkler, let's identify the exact intersection of coverage between these four sprinklers. It would be the midpoint of all four sprinklers, here:
Note here that if the north-to-south distance was less than 8'-8", we would still have compliant coverage. This is the maximum spacing between these sprinklers to still accommodate 130 sqft per sprinkler.
But what if our spacing in the east-west direction was less than 15-feet? Say it's 13-feet. Here's where that new midpoint lands:
Keeping that original sprinkler in the same place, we can repeat this process over and over again re-spacing the other three sprinklers in their maximum configuration:
If we keep running this process over and over, we start to see a trend in how this boundary exists:
Around each sprinkler, there's a natural boundary line, where if every sprinkler's box covers the floor area, then the 130 sqft-per-sprinkler coverage area is met.
This new box around the original sprinkler is what we're talking about. If this box stays with each sprinkler, then as long as all of the floor area is covered within a sprinkler's box, the coverage rules are met. Let's look at what this does practically when laying out sprinklers:
Why would this be helpful?
For one, you can now instantly see whether a layout adequately covers all floor areas. Think less dimensioning and hand-calculating whether a sprinkler is overspaced at 130 sqft.
For two, as you're laying out a system, it's easy to snap to the maximum opposite dimension. In the video above, I entered in 13-feet in the east-west direction, and 10-feet in the north-south direction. That's 130 sqft per sprinkler. However, with this box I could also just select the box and copy from the intersection of the boxes.
Above, this would be a code-compliant layout. There are no gaps in these coverage boxes.
There are exceptions to this to watch, though. Irregular boundaries might be inside a coverage box, but would exceed the maximum spacing or 130 sqft for the sprinkler.
These are exceptions though, and don't come up often. When I lay out sprinklers I evaluate these one-off scenarios when they crop up, and address them at that time.
Could the same shape be performed for a 100 sqft limitation? Yes, it can. Here's what a 100 sqft limit with 12-ft max spacing would look like:
Mathematically, how are these curves defined?
If a sprinkler is at (0,0) on an X-Y coordinate graph; to get any Y-coordinate on the 130 sqft box the equation would be
Y = 32.5 / X
(where X is the X-coordinate, and is between 4.3 and 7.5).
Why is this a power function? Simple - X x Y = 130 sqft. If we're drawing a curve to represent one-fourth of the overall area, then we take X x Y = 130 / 4, or, rearranged, Y = (130/4x) = 32.5 X.
Where would we draw the line for the 100 sqft box? Similar premise:
Y = 25 / X
(where X is the X-coordinate, and is between 3.9 and 6)
Why is this relevant?
Having coverage boxes for sprinklers can be a huge time saver if used appropriately. Model these in CAD blocks or Revit families and the time saved on sprinkler layouts and review alone could be major.
How do I draw these up? Are there familes or CAD blocks I can use? Yes - I've drawn these myself and uploaded the files for paid members here. Just login and download these files.
Have you used anything similar before? What are your thoughts? Comment on the blog here (www.meyerfire.com/blog) or shoot me an email at firstname.lastname@example.org. Always interested in your take.
Have a great rest of your week!
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Joe Meyer, PE, is a Fire Protection Engineer out of St. Louis, Missouri who writes & develops resources for Fire Protection Professionals. See bio here: About