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#54 - What is a Siamese Connection?

Posted by Jason Hugo & Cameron Sharp on 7/15/2016 to Fire Sprinkler System Components
Siamese Connection:

The fire industry has lingo for all kinds of equipment. I’m here to talk about the Siamese connection. This fire department connection (FDC) features two female inlets, and plays an essential role in providing supplemental water to sprinkler and standpipe systems. Fire departments typically utilize FDCs when large fires have threatened or bypassed initial suppression efforts. The two Siamese-like couplings connect servicing hoses that pump water from fire engines.

Learned enough already? Browse QRFS’ FDC Siamese Connections here.

FDCs are one of the most important and convenient allies for firefighters on-site. Because of this, there are several requirements in place to guarantee its accessibility. One of them has to do with the distance between a building’s fire hydrant and its Siamese connection. Any building that uses a fire suppression system, should have a fire hydrant positioned no closer than 30’ to the Siamese, but no farther than 50’. This is to ensure there are no issues with access to the building from obstruction of other fire apparatus. For an in-depth write up about all FDCs, including regulations and installation considerations, read our blog, The Role and Components of Fire Department Connections

Components of Siamese Connection:

The first thing people notice about the Siamese connection is the dual female inlets. These connections come in several sizes. Most buildings require 2½" inlets. However, three-inch (3”) is very common in New York City and San Francisco, where as 4" and 5" “Storz” FDCs are becoming common replacements for traditional FDCs due to their simple, quarter-turn connections. 

Siamese FDCs will contain either a single or double clapper to channel the flow of water coming into the system. The difference between the single and double clapper lies in the price. Double clappers are more expensive and use two clappers for added durability when supplying larger standpipe/sprinkler systems. Single clappers utilize a lone clapper, which swings freely to cover any unused inlets via water pressure. The attached, threaded brass ring that connects fire hoses, breakable caps and plugs, is known as the swivel. The swivel features lugs on the outer ring to support breakable caps.  

*The FDC pictured above contains a single clapper.  

The next components are the FDC plugs or breakable caps. Siamese connections need covering. Exposure can lead to accumulation of foreign material, and waterways will become clogged. Illustrated in the picture above are FDC plugs, which come standard with most purchases, and feature a chain for quick retrieval when removed. 

Siamese connections are required to have minimum signage. First responders need quick, specific system information when arriving on scene – whether its what type of sprinkler system is involved or if an FDC-connected system reaches throughout an entire building. Examples of common escutcheon signage include: “Standpipe & Auto-Sprinkler”, “Automatic Sprinkler”, “Test Connection”, or “Standpipe System”. A common 4” inner-diameter FDC escutcheon can be found here.

Things to consider when browsing for one:

The number of female inlets and clappers, as well as thread type are the most important features to make sure are correct. To do this, check with local authorities; jurisdictions can differ in preferences. Siamese connections are exposed FDCs, this means that you’ll need to purchase plugs and caps as well. These components prevent foreign material from clogging the FDC and its waterways. 

QRFS.com is proud to offer Siamese connections as well as several other variations of FDCs. At competitively low prices, we can provide you the fire department connection you need, as well as all the required components. Make the first step towards a complete fire protection program, and visit us today! 

This blog originally posted by Jason Hugo and Cameron Sharp at QRFS.com/blog on July 15, 2016. If you like what you've read, check us out at Facebook.com/QuickResponseFireSupply or at Twitter @QuickRsponseFS.

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