As someone who worked in industry, training on use is essential. At least watch a video on YouTube before you need to use one.

Learn P.A.S.S. Point, Aim, Squeeze, Sweep. Google it, having trouble copying on my phone.

We had annual training on them and the one time we really needed it, you could see who was goofing off during the class.

We had a fire break out on a machine that coiled hot steel. The grease use to lubricate the equipment caught on fire. The crew looked like the Keystone Kops when they turned on the water to the fire hose mounted by the coiler before unreeling it. Hose just blew up. Then they grabbed fire extinguishers (5) and after figuring out how to charge them, just aimed at one spot. By this time they finally called the fire department.

I grabbed the last extinguisher and swept the flames out.