Cannon JL - Cannon Group - #1

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24 The main rod is lubricated at every cycle. Cannon JL, an industrial success! The first year of industrial use for the new Cannon JL confirmed – and sometimes even exceeded – the promised expectations. Manufacturers of domestic refrigerators, insulation panels, refrigerated displays and cold stores obtained significant advantages in terms of reduced consumption of chemicals, better foam quality, more regular distribution of densities within their products. The innovation continues now in the direction of a wider range of blowing agents and applications. The Cannon JL is a new family of high pressure L-shaped mix heads. The acronym JL means “Jet Less”: the mixing of the two reactive liquids is not obtained by their impingement through the action of two injectors but by the high turbulence formed and maintained in a relatively narrow mixing chamber. The liquid components are metered in a common chamber and then flow to the mixing chamber trough variable restrictions where they acquire the necessary energy. At the end of the mixing chamber an L-shaped geometry deviates the flow into a much larger delivery chamber, slows down its turbulence and permits the delivery of the mixed blend with a very laminar flow. How does it work? The mixing of at least two fluids is normally performed trough turbulence, which can be created with static mixers, dynamic mixers, high speed of the streams and jets, impingement of jets and streams. All of them try a different way to maintain a high level of energy dissipation throughout shear into the fluid. Cannon latest innovation in this field consists in generating high turbulence by decreasing the size of the mixing chamber enough to generate a flow speed of tenth of meters per second and by using the front shape of the cylindrical piston which seals the mixing chamber to create high shear restrictions. This innovation produced the Jet Less head, a mixing head whose L-shape geometry permits as usual to reduce the turbulence of the flow exiting from the mixing chamber and to pour it in laminar form. Long nose… but reliable! The JL features a long and wide discharge duct, whose main purposes are to dump the high speed and turbulence of the stream, to perform a final mixing and to smooth down the whirling of the stream. Leaving the head the stream becomes laminar and can flow out into the mould with the ideal behaviour. Its length enables to reach very deep injection points. The up and down movement of the self-cleaning rod opening and closing the discharge duct removes and pushes out the foam residuals still in the pouring chamber, stripping out the reacted film from the walls. In the mean time the rod is acting like a pump for flushing and re-circulating a small quantity of lubricant oil, contained in a small spacer chamber built behind it. The relatively small sliding surface of the rod prevents the sticking of the surfaces and permits the use of a slim cylinder so the size and weight of the mix head are reduced, to be ergonomically handled also for manual operations. The first Cannon Jl head available on the market is the model JL 24/6, featuring a 200 mm long discharge duct, with an internal diameter of 24 mm and a mixing chamber diameter of 6 mm. This head – whose total output ranges from 300 to 2000 cc/sec - initially works with two components but more streams can be easily added. The wide range of output handled by this head, where no jets need to be adjusted when one significantly changes the output, imply that one size easily fits most of the conventional needs expressed by different industries and applications – therefore, within reasonable limits, there is no need for different heads to allow for the production of different parts. The most interesting operating feature is its working pressure: from 70 to 210 bar, allowing for a simplification of the dosing unit (pump type, filters, hoses, etc.). Industry success stories These heads have been industrially tested with rigid and flexible foam for more than one year and with frequent shots (up to 60,000 in one month), with full satisfaction. Several European manufacturers of insulating panels, domestic refrigerators, cold stores and refrigerated displays are currently using it with full satisfaction. An Eastern-Europe major supplier of domestic refrigerators has already ordered a second head, after having successfully tested a first one for one year and hundreds of thousand of shots - to be used for the production of large models characterised by a long filling path and difficult internal design. Using Cyclopentane and Isobutane-blown foams, this firm has measured a standard reduction of 2 percentage points of specific density maintaining all the previous physical and mechanical properties. At a very high annual consumption rate of chemicals, and considering their high unit cost, even a marginal saving like this helped this customer to pay back the investment in this new head in a very short time. An Italian producer of cold stores and walk-in coolers that works with HFC 134a reported a much better planarity in its panels, due to superior distribution of densities thanks to a better foam quality. A reason for this can be the head's capacity to “shoot” the liquid at a higher distance than that usually obtained with a standard L-shaped head. This allows for a more uniform geometrical distribution of the formulation within the cavity, without the need for overpacking the foam just to be sure that the whole panel will be filled. Another Italian producer of refrigerated displays started using it early in 2008 and has made until now nearly 70,000 injections: he reported significant improvements in filling complex panels, reducing slightly the injected weight and getting a finer cell structure, with improved insulation factor. Advantages The new Cannon JL head delivers several advantages: • a mixing method much more efficient than the traditional impingement: the higher efficiency has been computerstudied and simulated, and confirmed by field tests • the mixing pressure can be reduced to 70-80 bar depending from the chemicals. This allows for the simplification of the whole metering circuit (pump, filters, hoses etc) • a wider range of flow rates can be handled by the same mixing chamber: the maximum output can be five times higher than the minimum • it does not demands skilled operators to set the head's injection conditions: an easy setting of the central needle suits a variety of flow rates; pre-positioning of different values can be done manually or in automatic mode. • a very long discharge duct (patented) can enter pouring holes very difficult to access, and guarantees a laminar flow even at high flow rates: perfectly suitable for discontinuous insulation panel and for pipe-in-pipe insulation. • the use of the thin and long cleaning rod is mostly appreciated when using very sticky formulations • the internal geometry allows for a better handling of foams expanded with high-frothing blowing agents such as lowboiling Hydrocarbons, certain HFCs and natural liquid CO2 New models are now being prepared for future applications, in addition to those mentioned before: if you like the advantages, contact the nearest Cannon office. A JL mixhead can bring you significant advantages and savings! The distribution of foam in a refrigerator is improved since the liquid can be deposed at a longer distance from the injection hole and starts rising from a central position of the cabinet. The mixing efficiency is obtained by speed and turbulence, not by pressure. Rational design, few hoses, a long nose: the new JL is the fruit of 40+ years of Cannon research in PUR mixing efficiency. The three hydraulic valves are rationally positioned and the pin adjustment device features a micrometric regulation. The internal geometry of the new Cannon JL mixing head counts three mixing areas with different dimensions.