Aerosol Filling Machine

Overview

An aerosol filling machine turns an empty tinplate or aluminium can into a pressurized dispenser in four operations: dose the liquid product, drop in the valve, crimp the valve cup gas-tight onto the can, and inject propellant through the closed valve. Production lines run 30–120 cans per minute through these stations on an indexing transport, with the propellant work done inside a ventilated Safety Enclosure (the "gas house") because LPG and DME are heavier-than-air flammable gases.

The order of operations matters. The can is filled and crimped at atmospheric pressure, and only then pressurized through the valve stem. This "through-the-valve" gassing keeps the flammable propellant inside sealed hardware at every point, which is what makes 60-bar injection of liquefied petroleum gas survivable in a factory.

How it works

Cans arrive on the Infeed Conveyor and a Starwheel feeds them onto the Indexing Table, which dwells each can under a station for one machine cycle while Can Guide Rail rails keep them captive.

At the Product Filling Station, a Servo Motor strokes the Dosing Piston inside the honed Dosing Cylinder. The Rotary Shear Valve switches the cylinder between suction from the Product Manifold and discharge through the Filling Nozzle, so each stroke delivers one metered shot, typically held to ±0.5% of the set volume. The spring-loaded nozzle poppet snaps shut at the end of the stroke to prevent drips onto the can curl, where residue would spoil the crimp seal.

The Valve Placing Station takes bulk valves in the Vibratory Bowl Feeder, whose vibratory ramps orient them cup-up and reject any other attitude. Oriented valves slide down the Valve Feed Chute to an escapement, and the Pick-and-Place Head guides the dip tube down into the can and seats the cup loosely on the curl. The Valve Presence Sensor confirms a valve is present; a can without one must never reach the gasser.

Crimping is the seal that holds for the life of the product. The Crimping Head descends, its Crimping Collet segments enter the valve cup, and the tapered Collet Expansion Cam spreads them outward, clinching the cup skirt under the can curl against its gasket. The Crimp Height Adjuster fixes crimp depth at 4.4–5.4 mm and the expanded diameter at 27.0–27.5 mm per FEA standards; a Pressure Sensor in the actuation line flags under-force crimps. Get either number wrong and the can leaks slowly or bursts in the water bath test.

Gassing happens inside the booth. The Gassing Head clamps onto the crimped cup, its Gassing Cup Seal isolating the valve area, then depresses the stem and forces a metered charge from the Propellant Dosing Cylinder through the open valve. Because the valve orifice is about a millimetre across, the Gas Booster Pump supplies propellant at 40–60 bar to push 50–300 ml of liquefied gas through in under a second. Released, the stem reseals and the can is live, typically at 3.5–5 bar internal pressure at 20 °C.

Safety systems

The Safety Enclosure is the regulatory heart of the machine. Sheet Metal Panel walls form a booth swept by an ATEX-rated Blower Motor exhaust fan pulling air down and out through the Exhaust Duct, since propellant vapours pool at floor level. Two Gas Detector heads monitor the lower explosive limit and trip the line at 20% LEL; Safety Interlock Switch switches stop gassing the instant a door opens. All electrical hardware inside the zone is Ex-rated, and the Control System cabinet with its PLC Controller, Power Supply and safety Relay bank sits outside the zone, connected through barriers.

Actuation throughout is pneumatic rather than electric inside the booth: the Pneumatic System system conditions plant air through the FRL Unit and sequences the Pneumatic Cylinder actuators through the Solenoid Valve Bank.

Variants

Semi-automatic benches separate the same four stations into hand-loaded units running 10–25 cans/min, common for contract fillers and aerosol startups. Bag-on-valve lines replace the product filler with a station that fills product into a laminated bag welded to the valve, with compressed air or nitrogen gassed into the can around it. Compressed-gas (N₂/CO₂) fillers omit the gas house entirely but gas at higher pressure, since these propellants do not liquefy in the can. After filling, every can passes a heated water bath at 50 °C per transport regulations, where internal pressure rises roughly 50% and leaking crimps reveal themselves as bubble trails.