The Auto-Electric Air Heater.
This invention is the property of the DeVilbiss Manufacturing Company, and is intended to overcome the tendency of the air to cool as it leaves the nozzle in spraying, while it tends to keep it heated till it reaches the work. It also raises the temperature of the varnish or enamel, producing a smooth, even finish.
In addition to heating the air, the auto-heater warms the nozzle, thereby raising the temperature of the varnish. Because of the heated air and warmed material there is a complete elimination of the pitted, pebbled or mottled effect so noticeable when "short oil," quick setting or heavy bodied varnishes or enamels are sprayed on flat surfaces. The auto-heater enables Aeron users to improve the quality of many classes of work—in many instances it opens up an entirely new field of usefulness. The auto-heater and the air transformer set together insure clean, dry and warm air at the proper pressure, which is an important factor in the production of the best Aeron results.
The auto-heater applies the heat at the last possible point before the air enters the Aeron; as a consequence there is absolutely no loss or waste of heat, as would be the case if the air were heated at some other point and then passed through the hose to the machine. It is very easy to understand that if air heated before entering the hose retained sufficient heat to be of service when reaching the nozzle, it would be so hot that it would destroy the hose. In the only practical way, the auto-heater maintains the heat in the air at the proper degree till the spray reaches the work.
The auto-heater is light, yet rugged in construction. It has no exposed contacts. The conductor wires run through the air hose. It can be attached to any style of Aeron without difficulty. There is an automatic cut-off furnished with every auto-heater. Placing the Aeron in the cup holder, or hanging it on the hook, automatically cuts off the current—picking up the Aeron automatically turns on the current. This automatic control effects a great saving in current. As a protection against overheating the auto-heater is equipped with a fusible safety disc, which melts, allowing the air to escape, if current is left turned on by accident when the Aeron is not in use. This safety device operates within four minutes. Several extra discs are furnished with every outfit. The auto-heater can be connected to any electric light socket, and consumes only 250 watts current when in operation.
The construction of the auto-heater will be understood on reference to Fig. 91.
Another interesting heater is supplied by the Airostyle & Lithos, Ltd., a number of which are in use in this country Its general form can be seen on reference to Fig. 102, page. 165, which shows a gas-heated type. The same heater is also supplied either electrically or steam heated.
In all types it has the same general features, namely, a water-jacketed colour pot, a special coil for heating the air supply, which is afterwards passed through the water jacket for the dual purpose of raising the temperature of the jacket and damping down the air temperature at the same time. To a convenient standpipe the hot air is carried and distributed to the pistol, and also to a special jacket round the colour tube.
The Airostyle pistol is provided with an adjustment which admits of the hot air by-passing the whole time so, maintaining the pistol at the same temperature as the colour pot and ensuring a steady flow of the japan.
The heaters are mounted on a stand at the side of the hood and are complete with pressure gauges, regulating valves, special burner for gas, or an electrically heated pot giving three heats, or for steam giving a wide range of temperatures controlled by the steam pressure through a reducing valve. It must be explained that the same result is obtained no matter which form of heater is employed, and that in no case can the japan be burnt. The heaters are used for thick black tar varnish, or cycle japans, also for certain gum or glue mixtures and special varnishes.