How Do I Measure an Existing System?

MeyerFire University | FX102.03B

By Chris Logan, CFPS, RSE

RESOURCES

• Notes Page

RELATED VIDEOS

• FX102.04

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TRANSCRIPT

A project with existing sprinkler? Where do I start?  

When performing tenant fit ups, adding additions to existing buildings or during occupancy changes in buildings without contain existing sprinkler systems, having a good set of existing sprinkler drawings is critical to create tender submittal and construction drawings.  

Being able to locate, identify, and create as built sprinkler drawings creates a positive workflow for both the office and field staff.  

Here's how I identify or create existing sprinkler system drawings.  

When estimating or designing for a project that contains an existing sprinkler system, my first question for the project manager is if existing sprinkler drawings, commonly referred to as as-built sprinkler drawings, exist?  

If as built sprinkler drawings exist in digital form, I'll upload a copy to PlanGrid as discussed in a previous session for use on site.  

If only hard copies are available, I make multiple copies for myself to use and I like to maintain one original to keep on file. 

For more detailed review of the tools I use for site visits, please review the session on tools for  pre-bid site visits.  

I will quickly go over the tools I use: 

A 30-foot tape measure, a laser measuring device, a tablet with PDF editing software, a rolling table with a flat surface if using hard copy drawings or a laptop, and a PPE kit, including but not limited to safety glasses, boots, hard hat, reflective vest, all arrest gloves.  

Be sure to check with your site contact to confirm if any site specific PPE is required. 

When arriving on site, get yourself familiar with the exterior of the building.  

Do a quick walk or drive for larger buildings around the outside. 

While doing this, there are a few things I'm looking for.  

I look for fire department connections, outside water, modal gongs and exterior drains.  

This may indicate where riser locations are on the inside of the building.  

Other things I look for on the exterior of the building are inspectors test discharge elbows or exterior projections that contain sprinkler protection.  

This gives you a good idea of the size and shape of the building.  

Finally, it's time to get inside and begin. 

Start by confirming the overall accuracy of the drawings if provided.  

Have additions or undocumented renovations taking place that are not shown in the drawings you have has the sprinkler system been modified from the original installation?  

Take a walk through after having been familiarized with the drawings to see if anything major stands out.  

Get familiar with the piping layout, main runs and line installation and open areas of the building. 

Typically in concealed areas, the lines will be run similar to the open areas. 

What I like to do when measuring existing systems is start at the main incoming water supply and work towards the project area.  

I use my tape measure to get a side to side and front to back measurement off of structure to locate my incoming water supply or the spigot. 

I create a riser diagram using elevations and pipe lengths using standard P and ID or piping information diagram symbols.  

Sometimes older systems hydraulic data plate will be missing. If one is still available, document the information given on the plate, including the original system design information, including system discharge and pressure required.  

If a fire pump is provided for this site document all pump information including the type of pumps, such as vertical end line or horizontal split case, as well as the rated pressure and volume. 

Requesting the latest annual fire pump performance test gives you all the information you need to calculate your system from the discharge flange of the fire pump.  

You should now have a detailed drawing of your sprinkler riser in fire pump room. 

Move on to the express or feed mains and continue on towards your project area.  
 
Now that the riser and pump room is complete, we continue on through the piping network and on towards the project area.  

There are a few different ways of doing this, and the way I like to do it is to get a sprinkler layout, then pipe to the sprinklers.  

Again, measuring off structure, we locate on the drawing normally in the corner of a structural bay. I like to measure along a single line.  

Sprinkler to sprinkler to the end of the sprinkler line.  

I measured the distance from line to line along the main and simply copy and paste this similar line along the main provided they are typical sprinkler spacing.  

This can be accomplished quickly if sprinkler spacing is typical from bay to bay. 

Checking the sprinkler orifice size and data information of the existing sprinklers is done by observing the deflector.  

Older sprinklers may have the temperature rating stamped on either the frame of the sprinkler or the detection element.  

A victaulic no go or other type of piping caliber can be used to ensure you are getting the correct pipe sizes as you travel through the system.  

Intermittently, check your sprinkler distance off of structure and compare to your as built drawings if as builts are available.  

If attempting to trace piping above inaccessible concealed spaces, a rule of thumb for my installation days is that fitters tend to install the frame arms of sprinklers parallel with the lines above.  

This helps service fedders down the road with tracing sprinkler piping, giving a general idea of the piping network above.  

This rule is not consistent when concealed sprinklers are installed, but is common for semi recessed or flush type sprinklers. 

Creating as built sprinkler drawings can be a monotonous and tedious task.  

By performing this task yourself, you can ensure that you were working off an accurate portrayal of the existing sprinkler system.  

In short, use as much information as possible, but never trust provided documents.  

Allow yourself to over inform yourself with the project. 

Document, document, document. Take the time to review the entire piping network.  

You will never overload yourself with information.  

I'm Chris Logan, this is MeyerFire University.