Hun: Unit of measure for metal rebar
A coolthaihouse reader was interested in the determining the specifics regarding the unit of measure commonly used with rebar – the hun (à¸«à¸¸à¸™). I’ve asked the question regarding this unit of measure before and was assured that each hun was equivalent to 3 millimeters in diameter. So a 3 hun piece of rebar should be 9 millimeters in diameter, correct?
Not so quick, it also depends on the grade of the rebar. Light designation (bow à¹€à¸šà¸²) rebar is less expensive and can be formed (bent) on an anvil using hand tools. The diameter will also be less than the associated hun designation, so a 3 hun light rebar might only measure slightly over 6 millimeters in diameter. On the other hand ‘full’ designation (dem à¹€à¸•à¹‡à¸¡) should always be 3 millimeters in diameter for each hun designation. Our foreman here says the differential between bow and dem is 3 mm at each hun designation. So, for example, 4 hun dem rebar would have a diameter of 12 mm where as 4 hun bow would have a diameter of 9 mm.
One definition in a Thai – Thai dictionary which refers to measure is this: standard Chinese unit of measure with one hun = 1.5 / 16 inches. This works out to be different again from 3 mm, falling somewhere in between 2 to 3 mm. As a practical matter, 3 mm is the standard used when applied to rebar diameters.
Thanks to reader Doug for looking into this……
Update 28-May. Just bought some 6 hun PVC water line sections. The receipt prints the size as 20 mm. or 3/4 “. Just measured it and this is correct for the inside dimensions. When asked about the descrepancy (why is it not 18 mm which would by 6 times 3 mm?) my foreman says the hun measure isn’t the same when applied to PVC piping.
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