What is the exact size of an oxygen tank valve or the valve nut and what is the exact size of an oxygen tank valve wrench?

The size of an oxygen tank valve nut typically measures 7/16 inch or 3/4 inch, depending on the type of valve used, with the most common being the CGA 540 for medical oxygen. The corresponding oxygen tank valve wrench usually features a size that fits these nuts, commonly a 7/16 inch or adjustable wrench, but it's essential to verify the specific tank and valve type. Always consult the manufacturer's specifications for precise dimensions.