Energy sources on a typical piston filler
Every machine is different: check your model's nameplate, wiring and the manufacturer's manual. This is where most piston fillers get their energy and how it is usually isolated.
| Energy | Typical magnitude | Isolating device | How to control it |
|---|---|---|---|
| Electrical | 120–240 V controls (and heaters, if fitted) | Machine disconnect or plug | Switch OFF and lock and tag the disconnect, or unplug and fit a plug lockout cover. |
| Pneumatic (compressed air) | Compressed air, typically 80–100 psi | Lockable air shut-off / dump valve at the machine inlet | Close and lock the air valve, then bleed the circuit until the gauge reads zero. |
| Gravity (raised or suspended parts) | Product weight in the hopper; piston position | None | Empty the hopper if the task requires it. Do not reach under the nozzle until air is bled. |
| Thermal (heat) | Heated hopper or jacket (if fitted) | None — cool down | Let heated parts cool before contact. |
Shutting it down
- Stop the fill cycle with the normal STOP control.
- Close the product supply valve to the hopper, if fitted.
Releasing stored energy
- Bleed all compressed air: open the dump valve and cycle the controls until the piston no longer moves.
- Check the air gauge reads zero.
Verifying isolation
- Press the cycle start and foot pedal: piston and valves must not move. Return controls to OFF.
Things people miss
- Air can stay trapped between valves and cylinders: some cylinders need manual bleeding or blocking; check the pneumatic diagram.
Turn this into your written procedure
Add your company, the machine ID, the voltage and where each disconnect and valve is. You get a machine-specific procedure that follows the structure of 29 CFR 1910.147(c)(4), with an approval block and printable DANGER tags.
Start with the piston filler templateQuestions
Does a piston filler need its own lockout procedure?
OSHA 29 CFR 1910.147(c)(4) requires documented procedures for the control of hazardous energy. A procedure is not required only when all eight conditions of the exception in (c)(4)(i) are met, for example a single energy source that can be readily identified and isolated. Most machines with more than one energy source need a written, machine-specific procedure.
Is unplugging enough?
For cord-and-plug equipment, the lockout standard does not apply when the equipment is unplugged and the plug is under the exclusive control of the employee doing the work (1910.147(a)(2)(iii)(A)). If the plug can be out of sight or reach, use a plug lockout cover with a personal lock.
Is the interlocked guard enough?
No. Guard interlocks and emergency stops are not energy isolating devices and do not replace lockout during servicing, cleaning or clearing jams.
General information, not legal advice. Verify every energy source on the actual machine and have the procedure approved by a qualified person.