ANSI Z49.1, Section 8.6.1 Question: Cylinders of liquefied gases shall not be charged to more than _____ the maximum capacity by weight or pressure. A) 1/2 B) 3/4 C) 1 D) 2/3

The question asks about the maximum charging limit for cylinders of liquefied gases according to ANSI Z49.1, Section 8.6.1.

According to ANSI Z49.1, Section 8.6.1, "Cylinders of liquefied gases shall not be charged to more than two-thirds (2/3) the maximum capacity by weight or pressure." This limit is established to ensure a vapor space remains in the cylinder, preventing dangerous pressure increases due to thermal expansion of the liquid.

Therefore, the correct fraction is $\frac{2}{3}$.

The correct option is D).

$$\boxed{\text{D) 2/3}}$$