What is the purpose of the backplate and harness in an open-circuit SCBA?

• A. To secure the cylinder to the wearer and distribute weight
• B. To store extra air
• C. To hold the facepiece mirror
• D. To power the electronic monitor

Answer: (A)

The backplate and harness are there to secure the cylinder to you and spread the weight so you can move comfortably and safely. The backplate provides a rigid surface that sits against your back, keeping the cylinder aligned and preventing it from shifting or tipping as you bend, crawl, or climb. The harness straps go over your shoulders and around your waist to lock the unit in place, distributing the heavy load across your core and hips to reduce fatigue and improve balance. This setup also helps keep the air hose and regulator positioned for quick access. The purpose isn’t to store air, hold a facepiece accessory, or power electronics—the air is in the cylinder, and those other functions come from different components of the SCBA.