Gas Meters: 2017 #40

A gas meter orifice:
(A) Typically has less than 10% of an effect...
(B) Should be installed with the beveled edge upstream. 
(C) Should be installed with the sharp edge downstream. 
(D) Typically has less than 20% of an effect...

The Guidebook (8 FAC 3 & 4) states gas orifice plates are installed with beveled edge downstream. So we know B & C are false.

The same page also says an orifice installed backwards reads about 15% low. So we know A is false.

Finally, since we know backwards is the greatest error it can have due to orientation (15%), D must be true.