Guide

The hidden energy in a packaging line

On a flow wrapper or a form-fill-seal machine, the main disconnect is only the first of several energy sources. Most packaging-line injuries during maintenance come from the others.

Compressed air

Pneumatic cylinders move jaws, knives and pushers. Closing the air supply is not enough: air stays trapped in the lines and cylinders. Use a lockable shut-off with a dump valve, bleed the circuit until the gauge reads zero, and check the pneumatic diagram for cylinders that hold air between valves.

Electrical, including drives

Lock out the main disconnect on the control cabinet. Servo and frequency drives can keep a dangerous charge in their capacitors for minutes after the power is off: wait the time written on the drive before electrical work, and let a qualified person test for absence of voltage.

Heat

Sealing jaws and heaters stay hot long after the machine stops. Let them cool before you touch them or change seal tape.

Tension and gravity

Film reels and dancer arms are under tension; a released dancer can snap. Vertical form-fill-seal machines have jaws and parts that can drop. Release tension or lock the dancer, and block raised parts with the manufacturer's pins before reaching under them.

Gates and e-stops are not lockout

Safety gates, interlocks and emergency stops protect operators during production. They are not energy isolating devices and do not replace locks during cleaning, changeovers or jam clearing.

One procedure per machine, one group lockout per line

Each machine on the line needs its own procedure. When a crew works on the whole line, use a group lockout: one lockbox, each person's personal lock on it, and one person coordinating (1910.147(f)(3)).

General information, not legal advice.