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+Jason Hugo

#67 -- What Size FDC Break Cap or Plug Do I Need?

Posted by Jason Hugo and Anna Hartenbach on 6/15/2017 to Standpipe Systems and Fire Department Connections
Upon first arrival at the fire scene, an eager firefighter approaches the Fire Department Connection (FDC) on the side of your building to connect a hose and pump life-saving water into the building’s standpipe or sprinkler system. Unfortunately, he is thwarted by unwanted dirt and debris that have accumulated on the inside of the FDC’s inlet. Precious time is lost as he stops to clean it out, but he knows these items could obstruct the proper flow of water inside the building if they are not removed.

If only there was a device that could’ve prevented this delay!?!

There is a device for just this purpose! FDC break caps or plugs are both perfect solutions to provide coverage for the inlets on a FDC. In another article, we explore break cap and plug options at length. If interested, you can check out this article here.

In today’s article, we’re going to help you pick the RIGHT SIZE FDC plug or cap. Commonly, the impetus for ordering new break caps or plugs is an impending or completed inspection by your fire marshal. Avoid further delays, anxiety, and even fines by ordering the right size cap or plug the first time to avoid returns!

FDC break caps and plugs come in various sizes, materials, and finishes. Which is right for you?

So what size do you need?

In this pictorial guide, we show how to select between 1 ½”, 2 ½”, and 3” break caps and plugs for your building’s FDC. You’ll learn that your location can determine the proper FDC cover size and that the measurement describes the inside diameter of the waterway, not the outer threads or... well, anywhere else. If this sounds helpful to you, let’s go! 

Already know what size you need? Click here to skip to our product page

What size of FDC Inlet Do You Have?

If you have a standard FDC like the one pictured and you measure the outside of the inlet, you’ll come up with a measurement of approximately 3 ½”. What size break cap or plug do you think you need?

FDC Inlet  FDC Inlet Internal
Inlet 1: This inlet measures about 3 1/2" on the outside Inlet 1: The inside ring measures 2 1/2" 

Incorrect Answer: 3 ½” 
Correct Answer: 2 ½” 

Why? Because the measurement that counts is the inside waterway of the inlet at 2 ½”, as evidenced by the image above. This is the most common size of a commercial FDC – about 98% of our customers have a 2 ½” FDC. Only New York and San Francisco commonly use the larger 3” size and residential homes are the only consistent users of 1 ½”, both of which we discuss below. 

2.5 Inch Break cap  FDC 2.5 Inch Plug 
                A 2 1/2" break cap measures about 3 1/2" in diameter      The inside diameter of a 2 1/2" plug is about 2 1/2"

Pictured above are the standard inside measurements for a 2 ½” break cap and a plug. While the plug is close at roughly 2 ½”, the break cap is wide enough to cover the full inlet. It doesn’t measure anywhere near 2 ½” which is what makes this just a little bit tricky.

2.5 Inch Break Cap on Inlet  2.5 Inch Plug on Inlet
                   The 2 1/2" break cap fits securely on inlet 1                         The 2 1/2" plug threads firmly in place
Even though the outside measurement of the FDC inlet is 3 ½”, you can see that the 2 ½” break cap and plug provide the appropriate closure.  

3” FDC Inlets

FDC Inlet 3 Inch Measurement  FDC 3 Inch Inlet Internal Measurement
                Inlet 2: The outside of this inlet measures well over 4"     Inlet 2: The inside measures right around 3"

Measuring the outside of this 3” FDC inlet (for demonstration purposes, we removed the outermost swivel from the FDC) may result in some confusion since it measures over 4”, which might lead you to wonder what size you need! 

Again, this is where the innermost measurement counts. The inner ring of the inlet is around the 3” mark. 

As stated above, these FDC inlets are used primarily in the New York and San Francisco markets. 

FDC 3 Inch Break Cap  3 Inch Plug
           The back of the break cap measures around 4"                          The innermost portion of the plug measures 3"

Once again, looks can be deceiving. The inner portion of the plug measures 3” to meet the sizing of the FDC inlet, but the break cap is around 4” just like the outer measurement of the FDC Inlet. 

3 Inch break cap on inlet  3 inch plug on inlet
                The 3" break cap provides an accurate fit on inlet 2           The 3" plug provides a reliable closure

Despite the outer measurements of the FDC inlet reaching more than 4”, both the 3 ½” cap and plug provide the right fit.

 1.5 Inch Inlet  1.5 Inch Inlet Internal
                Inlet 3: The outside measures more than 2"                        Inlet 3: The internal measurement is 1 1/2"

Pop quiz: To further emphasize today’s lesson, based on the inlet above, what size of FDC plug do you think you need? 

Incorrect answer: 2”
Correct answer: 1.5” 

Hopefully, you’re catching on! To reiterate, the internal measurement is where the break cap and plug get their identity—even if they aren’t actually coming into close proximity to the internal waterway. Since this FDC Inlet’s internal measurement is 1.5” then you need a plug to match up.

1.5 Plug Measurement  Plug on Inlet
                The inside of this plug measures right around 1.5"             Inlet 3: The 1.5" plug provides the perfect fit

As you can see, demonstrated above, the innermost portion of the plug is around 1.5” and it fits the 1.5” FDC inlet perfectly.

What Color of FDC Plug Do You Need?

If you’ve determined you need a 3” plug, either by measuring or because you’re in New York, you’ll need to make an accurate color selection. In accordance with New York City Building Codes (Local Law 58/09), mid-rise and high-rise building owners are required to paint Siamese connections to denote the type of system within. The purpose of this color coding system is to allow the fire department to quickly identify the system type.
  • Red: For use with standpipe systems (learn about Standpipe)
  • Green: Denotes a connection to a fire sprinkler system
  • Yellow: Combination standpipe and fire sprinkler systems
If you’re purchasing a red, green, or yellow plug it’s important to note that they’re only available with New York Fire Department (NYFD) Threads. Our unpainted 3” plugs come in NYFD or NST threads.

The QRFS Difference

At QRFS, it’s our goal to assist you in finding the RIGHT products so you walk away with a solution, not further questions. 

We offer a full selection of plugs including brass and aluminum alternatives. For 3”, we stock green, yellow, and red plugs to satisfy New York Fire Department (NYFD) color-coding requirements, in addition to unpainted, all in ductile iron. Now that you know your options, check out the table below to find the best choice for your FDC inlet!

  • Our most popular option!
  • Easy installation
  • Breaks easy with the butt of an ax
  • Low cost - sold in sets of 2
Aluminum Break Cap
  • Durable
  • Easy Installation
  • Breaks easily with the butt of an ax
  • Low cost - sold in sets of 2
3 Inch Break Cap
  • Durable
  • Easy installation
  • Breaks easily with the butt of an ax
  • Low Cost
  • 3" break caps available for New York and San Francisco FDC inlets
Brass Plug and ChainBrass FDC Plug and Chain - 1 1/2", 2 1/2", or 3"
  • Hard-wearing brass exterior
  • Threaded to meet your local requirements
  • Includes chain to avoid loss in an emergency
Aluminum Plug
  • Lightweight, yet sturdy
  • Comes in a gold/brass finish to match your FDC
  • Includes chain to avoid loss during an emergency
Polished Chrome Plug
  • Polished chrome finish
  • Threaded to meet your local requirements
  • Includes chain to avoid loss in an emergency
         Green FDC Plug
Cast Iron FDC Plug and Chain - 3" 
  • Available in red, yellow, green, or unpainted
  • Red, yellow, and green have New York Fire Department (NYFD) threads
  • Unpainted can have NYFD or NST threads
  • Lightweight, yet sturdy
  • Includes chain to avoid loss during an emergency

All options are available online 24/7 – and in stock in multiple locations within the United States. Order today and you’ll receive an excellent product delivered extremely fast backed by QRFS customer service. Doesn’t get much better than that! 

Still have questions or concerns? Leave them in the comment section below or contact us here and we’ll do our best to answer them quickly. 

This blog was originally posted by Jason Hugo and Anna Hartenbach at QRFS.com/blog on June 15, 2017. If you’ve “found your right fit” after reading this, check us out at Facebook.com/QuickResponseFireSupply or on Twitter @QuickResponseFS.

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