What is the purpose of the lay line on a flexible fuel hose?

• A. To monitor fuel hose twist
• B. To indicate flow direction
• C. To denote pressure rating
• D. To show production batch

Answer: (D)

The lay line is a visual reference painted along the hose that serves as a twist/orientation indicator. It gives you a quick way to see if the hose has rotated or twisted during installation or service. If the line starts to rotate out of alignment, it signals twisting that can lead to wear or stress at the fittings, so you can correct the routing before it causes a failure. It isn’t used to show flow direction, pressure rating, or production batch.