Bought a cheapie for the shop while in Wichita last weekend...turns out
the sight glass leaks (around the cover seal, not the threaded portion).

Parts show it numbered but don't give dimensions...being the trip
to/from Wichita to return it would cost more than the total cost, and
not sure if the contact will follow thru that they'll supply a
replacement gratis, look and can find gazillion replacements pretty
cheap but I'm not positive on the thread size.

It appears that a 3/4" NPT plug will stop the leak but it threads quite
deeply so got to wondering -- many are listed as a 27 mm but no pitch
given so is there a rough equivalent between a metric and NPT that could
possibly be interchanging?

For $3 and change/ea and free shipping _could_ just order a sample but
thought might see if anybody here has info...

Push come to shove, can simply use a 3/4x1/8" reducer and a plug and
check it the old fashioned way, of course...

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