Liquid propane gas in bottles is used all over the world. When empty, the bottles are refilled. Siraga (Buzan Vais, France) designs and assembles filling installations for companies that fill bottles with liquid butane and propane. These installations may range from a simple filling apparatus to a large filling plant.

Gas bottles come in a wide variety of sizes, diameters and weights. The bottles also are returned in conditions ranging from virtually new to damaged or rusted. Some bottles are empty on return. Others are half full. The glass bottle valves and covers also differ according to the country where they're used.

Despite all the variation regarding packaging or bottle valve type, the project design specialists at Siraga are endeavoring to simplify the work through standardization. All bottle-centering devices are the same, and stock includes subassemblies, electrically actuated valves, standard cylinders and directional control valves.

The circular conveyors at filling plants are fitted with eight to 36 filling stands. The bottles are inserted, transported and removed automatically. The gas distribution system is situated in the center of the circular conveyor. The gas is distributed via tubing to the individual filling stations. The gas bottle valves can be automatically or manually connected and opened, removed and sealed.

Siraga uses at least 40 pneumatic cylinders from Bosch Rexroth (Buchanan, MI) in each of the filling installations. These cylinders are used to center the gas bottles and to remove them from the conveyor after filling.

For safety reasons, there is one cylinder for every filling stand. It is important that positioning problems be avoided when handling liquid gas. Also, the gas bottle valve is opened in each case with a working cylinder. The company also compensates for the different bottle sizes within the circular conveyor by using pneumatic cylinders.

As with all components of the circular conveyor, the pneumatic cylinders are standardized components. This enables the plant to be put into operation quickly and helps avoid delivery problems. Most cylinders used in profile design are double-acting and are fitted with magnetic sensors and pneumatic cushioning.

Because the application is subjected to some severe environmental conditions, Siraga uses special cylinder materials. The cylinders are made of electrically zinc-plated aluminum profiles to prevent corrosion. The piston and rod are also made of noncorrosive materials. Cylinder design is determined by the load, operating speed and dynamic forces affecting the conveyor. For safety, Siraga chooses cylinders that are slightly oversized for the job.

Siraga also uses Bosch Rexroth cylinders and pneumatic control valves in circular conveyors used to remove the covers from the bottles. Eighteen pneumatic cylinders ensure that the covers are removed from as many as 2,400 bottles per minute.

For more information on cylinders, call 269-695-0151 or visit