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The Importance of Thread Measurements when Selecting Fire Hose Couplings

Determining the exact size and fitting requirements for a fire hose coupling can be extremely difficult, but doing so will save you time, money, and perhaps property and lives. The slightest under/overestimate in coupling size can result in lowered water pressure, major leakage, or no functionality at all.

You probably have quite a few questions about your hose coupling and how to be 100% sure that the size you order is correct. Thankfully, JME has measuring charts and the couplings necessary to make the hose coupling selection process as easy as possible on your time and budget.

A few preliminary measurements are essential to figure out which fire hose coupling fits on your fire hose. The simplest way to identify your coupling size would be to check with its manufacturer, or research the coupling required for your current fire hose.

However, if this is proving to be difficult, there are a few tests that can help you figure out which size coupling is the ideal fit on your fire hose:

1. Count the number of whole threads at their largest amount, measure the distance peak-to-peak across them, and divide the number of threads by that measurement. This determines the Threads Per Inch (TPI).

2. Figure out if the thread is straight or tapered. Tapered threads are slightly conical, while straight threads contain a rubber ring to provide an airtight seal. Refer to JME’s diagram if needed.

2a. On straight threaded hose couplings, measure the “Outside Diameter of the Male” (ODM) or the “Inside Diameter of the Female” (IDF) from peak-to-peak of the threads.

2b. On tapered thread hose couplings, the ODM or IDF can be measured at the large or small ends, and should be done from peak thread to peak thread as well. Follow up by measuring the Outside Diameter (OD) of the unthreaded pipe.

Once you discover the dimensions of your fire hose coupling, refer back to the JME chart to identify the specific brand and its hose compatibility. Ensuring you picked out the correct coupling for your fire hose before purchasing it not only saves you time and money, but also gets your hose back into working condition as soon as possible.

JME has every size coupling to fit any household fire hose, and offers only the highest quality products to ensure their fire fighting products are safe, secure, and durable when you need them the most.

The following video is also a great tutorial for determining the size of thread you have: