Back in the early days of drums it was difficult to precisely mold fine pipe threads directly into the drum. The fine threaded plugs would cross thread, strip out or leak when you tightened them. The solution to this was the heavy, strong buttress thread. Today, plastic drum technology is vastly improved, and NPS plugs now perform just as well as buttress plugs. However, most drums still include a buttress thread.
Plastic drums most often have two bungs; a 2" NPT opening and a coarse 2” buttress thread opening. The problem is that the "buttress" thread doesn't fit many standard faucets or pumps.
The solution to this is the 180132 2" Buttress x 2" NPT Drum Adaptor
. This adapter will thread into the buttress thread on your drum and adapt to a 2” female NPT thread that you can use to connect standard pumps, faucets and vents.Don't know what thread you have on your drums? Here is how you tell the difference between buttress and NPT threads.
A way to distinguish between NPT and Buttress is by their appearance. Buttress threads have a thread where there the lines are spaced further apart making them look more coarse. So they are sometimes called "coarse threads". NPT, by contrast, has threads much closer together so they are often referred to as "fine threads".
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