The best tool to open and close the system access valve on a refrigeration system is the ______.

• A. Screwdriver
• B. Wrench
• C. Pliers
• D. Hammer

Answer: (B)

Opening and closing the system access valve on a refrigeration system requires applying torque to the valve stem with a tool that can grip firmly without slipping or rounding the stem. A wrench provides a solid grip on the valve’s hex or square stem and lets you apply controlled torque to fully open or close the valve. This ensures a reliable seal when closed and prevents damage to the stem or packing. Using a screwdriver can slip or strip the stem, pliers can slip or crush it, and a hammer would damage the valve and is unsafe. In many cases, a valve wrench or an appropriately sized adjustable wrench is used to fit the stem precisely and operate the valve safely.