If 5/8 inch O.D. fittings are unavailable for 5/8 inch ACR tube, which copper water tube size could be used?

If 5/8 inch O.D. fittings are unavailable for 5/8 inch ACR tube, which copper water tube size could be used?

• A. Water tube fittings cannot be used with ACR tube
• B. 5/8 inch
• C. 1/2 inch
• D. 3/4 inch

Answer: (C)

Fittings are sized by the tube’s outside diameter. A fitting labeled for 5/8 inch O.D. is made to slip over a tube with a 5/8 inch outer diameter. The copper water tube that has that same outer diameter is the 1/2 inch nominal tube, which actually measures 5/8 inch on the outside. So you can use 1/2 inch copper water tube with the 5/8 inch O.D. fittings. A 3/4 inch copper tube has a larger outer diameter (7/8 inch), which wouldn’t fit the 5/8 inch fittings, and a 5/8 inch nominal size isn’t a standard copper water-tube size.

Fittings are sized by the tube’s outside diameter. A fitting labeled for 5/8 inch O.D. is made to slip over a tube with a 5/8 inch outer diameter. The copper water tube that has that same outer diameter is the 1/2 inch nominal tube, which actually measures 5/8 inch on the outside. So you can use 1/2 inch copper water tube with the 5/8 inch O.D. fittings.

A 3/4 inch copper tube has a larger outer diameter (7/8 inch), which wouldn’t fit the 5/8 inch fittings, and a 5/8 inch nominal size isn’t a standard copper water-tube size.