What type of wrench is used on a cylinder and regulator fitting?

The use of a fixed end wide jaw wrench on a cylinder and regulator fitting is appropriate due to its design, which allows for a secure grip on fittings that may be subject to significant torque and force during tightening and loosening. This type of wrench provides a wide surface area that distributes the pressure evenly, reducing the risk of damaging the fitting or the wrench itself. The fixed nature of the jaw ensures stability and alignment with the fitting, which is critical when working with gas cylinders where leaks must be avoided.

While other wrenches have their specific applications, the fixed end wide jaw wrench is particularly well-suited for the cylindrical and regulator connections due to its versatility and robust nature in handling various sizes of fittings.