What does red-lining at 15 psi on acetylene gauges signify?

Red-lining at 15 psi on acetylene gauges signifies that this pressure level is a warning against increasing further pressure. This threshold is important because acetylene is highly flammable and can become unstable if the pressure exceeds certain limits, particularly in environments where there may be open flames or sparks. Operating at or above this red-line pressure can lead to hazardous situations, including the risk of an explosion.

This warning also helps ensure that the equipment operates safely within the recommended pressure range, allowing for optimal cutting performance without compromising operator safety. Other options do not address this critical aspect of safety and pressure management when using acetylene for oxyfuel cutting.