Where are Sidewall Sprinklers Used?

MeyerFire University | FX108.71G

By Joe Meyer, PE

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• One-Page Summary [PDF]
• Notes Page [PDF]

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TRANSCRIPT

Where are Sidewall Sprinklers Commonly Used? 

INTRODUCTION

Sidewall sprinklers – they feature an orientation that takes water and throws it across the room. But where do we use them? Why do we use them there? That’s our topic for today.  

So, let’s start at the beginning. 

THREE PRIMARY ORIENTATIONS (PENDENT, UPRIGHT, SIDEWALL)

We have three primary orientations that a fire sprinkler can be. And that is a pendent (which is notably spelled with an “e” not an “a”), an upright, and a sidewall. 

Let’s talk on pendents for a second.

A pendent sprinkler has a deflector that is below the heat-sensitive element. It takes water from a pipe above and distributes the water primarily downward in a conical shape. We usually use pendent-oriented sprinklers when we plan to locate the sprinkler below our pipe. That's pretty simple. This could occur when we have suspended ceilings, where we want to conceal the pipe, or sometimes even with exposed situations where we're trying to get the pipe as tight to structure as possible. Pendent sprinklers are also used below or to the side of obstructions.  

An upright sprinkler has a deflector above the heat-sensitive element. It takes water from a pipe below the sprinkler and distributes water, again, primarily downward in a conical shape. Upright sprinklers are used where the sprinkler is to be located above the pipe. They're most common in exposed structure areas without a ceiling where it's convenient to locate sprinklers closer to the deck above the pipe, and have some flexibility in where we wanna locate the pipe below. 

SIDEWALLS

A sidewall sprinkler has a deflector that's to the side of the heat sensitive element. It takes water from pipe adjacent to the sprinkler and distributes that water out and away from the sprinkler horizontally in its throw direction, which is way perpendicular from the wall, but also to each side of the sprinkler along the wall where the sprinkler is located. So, where the water throws out away from the wall, it spray both goes slightly upwards in its throw, but also down for coverage below the sprinkler and in front of the sprinkler. Looking at the sprinkler from above, it also sends water to each side. 

We use sidewall sprinklers in a few different situations. These examples that I'm going through today are just common ones that I've come across personally.  

USE #1: AVOIDING PIPE OR SPRINKLERS IN CERTAIN AREAS

So, the first situation where we often use sidewalls is where we're trying to avoid having piper sprinklers in a certain area. 

Let's say we have a particularly expensive or sensitive piece of equipment. It could be machinery, it could be a server, it could be communications room, some other piece of high value or critical infrastructure. 

Depending upon the ceiling construction and the size of the space, it could be possible to use sidewall sprinklers to protect the area while also not routing any sprinklers or pipe above the equipment. In a very rare instance, a piper fitting leaks, and I do say rare because that's not as common as many building owners might believe. The sensitive or valuable equipment, well, it's not at risk because the sprinkler and the pipe are not located above the equipment. If you have a leak or a drip situation, it's not located above the equipment, there's no risk of affecting that sensitive or expensive equipment. 

By using sidewall sprinklers, we're avoiding routing sprinklers or pipe entirely through a certain area. This would also be true if we have, say, an exterior projection or an overhang. Perhaps we don't wanna route pipe outside of the building envelope. In that case, we could use dry sidewall sprinklers, keep the pipe on the interior while protecting areas on the exterior without exposed pipe. Again, the situation is that we're trying to avoid having pipe or sprinklers in a certain area. In this case, we're trying to avoid having pipe in that freezing area outside so we use sidewalls and locate the pipe inside.  

This could also come into play with elevators and hoistways. Perhaps we don't want pipe routed above an elevator cab or in the vertical space, or an elevator cab or cables need to be free to move. Sidewall sprinklers could be a solution here.

USE #2: MEET CEILING CLEARANCES

Another example of where sidewalls come into play is where we want to keep clearances. 

Let's say we have a narrow utility tunnel that runs underneath a university campus that's only about 5 feet tall. Places like this actually do exist. If someone is going to have to walk that tunnel, we want to afford them as much clearance to the deck above as possible. 

So, in this case, sidewall sprinklers might be an approach that avoids routing pipe directly above a specific space and maintains a greater vertical clearance than having pipe directly above that space. This might also come into play where you have drive lanes or drive-thrus or tunnels or narrow pathways or shorter ceilings. 

USE #3: SAVE ON MATERIAL OR EASIER LABOR

Another situation where sidewalls are used is where we have the opportunity to save on material and by an extension of saving on material, we could also see savings in labor. 

This situation is common in hotels, apartments, and other buildings that are narrow and have smaller repeating room sizes. If the sprinkler main for a hotel is, say, routed down a corridor, then the amount of pipe that we would need to serve sprinklers within each unit, well, it could be reduced significantly by using sidewall sprinklers and running pipe from the corridor into the unit only so far as to reach that sidewall sprinkler. 

Now I caution that we could minimize pipe. It's not an always minimized pipe. That really depends upon the layout of our particular building and the individual units whether we're able to save pipe using this approach or whether routing pipe unit to unit is easier and it involves less labor. I'll save that debate for another day. For now, I just wanna point out that some narrow buildings with repeating units, we'll use sidewalls because there can be significant material savings by doing so. You'll see this if you stay in a lot of hotels. A lot of those units will make use of sidewall sprinklers because they can save on material. 

This concept could also apply where an area just might not be serviceable. What if we have a tall, narrow atrium that's over 40 feet tall? Sidewalls at the top could be advantageous if we ever needed to replace that sprinkler. Say there was a sprinkler activation or a 10-year sample testing said that the sprinklers needed to be replaced, while tall, open spaces would require a lift and a whole lot of work just to get access to that sprinkler. Whereas a side wall, it might be more accessible and may prove to save a lot of headache down the road. So here we're saving on hassle and convenience in being able to service that sprinkler in the future. 

USE #4: PIPE ROUTING IS CRITICAL

Another situation where sidewalls come into play is where the pipe routing to serve a sprinkler is critical. 

Let's say we're on the top floor of an apartment building and we are only protecting sprinklers within the apartments because there's a flat roof or because there's a non-sprinklered attic above. 

Now we could put pipe in that cavity or in the attic space and use pendent sprinklers that serve below that ceiling on the top level, but we might be creating an issue for ourselves. Will that pipe stay warm all year? What about infrequent freezes in the winter? NFPA 13 says we need to stay above 40 degrees Fahrenheit (4 deg C) in areas with water-filled pipe. 

Are we sure that that pipe in that area is always gonna stay warm? Are we sure that the insulation near that pipe or above that pipe won't ever be compromised in a way that'll cause freeze up in the future? 

Well, not always. We're not always confident that those pipes are gonna stay warm, and that's why in many situations like this, sprinkler designers will use sidewall sprinklers to avoid routing pipe through an area that's subject freezing. Instead of pipe in the attic and pendents below, designers will route pipe within the walls and feed it from underneath. This has been loosely termed a “birdcage” method or the “birdcage” method, which resembles the different bars that make up a bird cage. 

By using this method, water filled pipe can stay in the interior walls where they'll be kept warm and run up the wall to serve sidewall sprinklers within that wall. 

USE #5: BELOW AN OBSTRUCTION

Another situation where we use sidewall sprinklers is to throw below an obstruction. 

Now, when we say obstruction, many of us like to think of a 4-ft wide (1.2 m) wide duct, but what about maybe a large overhead door? 

If we can't run long segments of pipe underneath that door because our hangers would be over their spacing limit, well, what are our options? In some cases, sidewall sprinklers can be used to throw longer distances and protect below a large overhead door or a large obstruction. It might otherwise be difficult with a pendent or an upright because we can't always get a hanger below those obstructions.  

So, a newer hazard where this has come up is car stackers where the stacker itself needs to be able to lift and move cars. So stationary pipe hangers and sprinklers won't work within that vertical space. Sidewalls are a common application here too. 

USE #6: SPECIAL CASES

Lastly, and perhaps less common for ordinary light commercial work or couple special cases, one would be to protect steel building columns. In some situations, active suppression has been used as a method of maintaining steel structure during a fire from getting too hot and compromising the structure or compromising the integrity of the building or compromising the integrity of the building. Sidewalls deliberately springing water down a steel column is another area where we might see sidewall sprinklers. 

Another special case that technically falls within this list is window sprinklers or exterior exposure protection where we use vertical sidewall sprinklers. These are a special orientation that throws water horizontally but is fed from above (I know, it's still a sidewall) to achieve a specific spray pattern, prevent glazing or some other surface from reaching high temperatures.

SUMMARY

So, where are sidewall sprinklers used? 

Now we went through a handful of examples for common uses of sidewall sprinklers. There are many potential applications and surely there’s more than we covered today, but some of the most common reasons why we use sidewalls and where we use sidewalls are:

• To avoid routing pipe or sprinklers in certain areas
• To allow for greater clearances
• To save on pipe or labor
• To route pipe in specific areas, such as heated areas or walls
• When protecting below obstructions
• Or, in special cases 

We talked about a lot of upside to sidewall sprinklers in this one. In our next segment, we’re going to explore the deep dark underbelly of the sidewall sprinkler – it’s downsides. 

I'm Joe Meyer, this is MeyerFire University.