Couplings are tightened and loosened with a __________ wrench.

Couplings are specifically designed to connect and disconnect pipes or hoses, often found in firefighting equipment and infrastructure. A spanner wrench is ideal for this task because it is designed to fit various sizes of nuts and bolts, especially those that are hexagonal or have a similar shape, which is common in coupling assemblies.

The spanner wrench allows firefighters to achieve the necessary torque to secure the coupling tightly and ensure that it will not loosen during operation. Its design facilitates ease of use in tight or awkward spaces, often encountered in emergency situations.

Other types of wrenches, such as socket and adjustable wrenches, may not provide the same level of fit or stability for coupling applications. Torque wrenches, while useful for measuring the amount of torque applied, are not specifically designed for general coupling adjustments. This makes the spanner the most effective tool for the job.