may have screwed up my order

[mrpizza]

So i ordered all new fittings for my air compressor, 1/4" npt from Mcmaster today. I figured this was the right size because the fittings I took off screw into a 1/4" npt galvanized cap. Am I correct here?

Also, are 1/4" pipe threads much larger than 1/4" regular bolt threads? My 1/4" taps don't even come close to touchig in the tank, but the fittings fit the 1/4" npt cap. The fittings I took off the tank fit the 1/2" hole on my bolt measuring card thing, but also fit that cap. I don't know much yet about pipe fittings and threads.

 

[usdemt]

1/4inch is pretty standard and I am going to say that you got it right. Pipe is measure by inside diameter, where as bolts are measured from outside. So that is why 1/4 pipe plus the wall thickness X2 of 1/8= 1/2 or your 1/2 bolt size.

 

[mrpizza]

Makes sense, thank you for the new info!