One of the Aerograph types of power pump and tank is shown below. It is strongly built, easy working, and is fitted with metal extending rings and metal valves, which will supply enough air for three spraying painters. In the illustration is shown the pump fitted with an automatic regulator, but this may be dispensed with if desired. The regulator, therefore, will be found of great value, not only in saving power, but also in the wear and tear of the pump. The tank is fitted with an air gauge and a speed valve, and the dimensions of the air receiver are 18 inches diameter by 30 inches high, and the pump has a bore of 3 in. while the stroke is 7 in. The power required is 1 h.p.
Fig. 77.—The Airostyle Plant—General Arrangement of Accessories.
The Supply of Paint.
For lacquering or coating small articles a spray may be used which is constructed with a cup to contain the paint, but for any heavy painting where large surfaces are to be covered quickly a cup on the handpiece is not of much utility, and it is necessary to provide a means to keep the supply of paint to the handpiece continuous. This is done in two ways: By an overhead paint pot, allowing gravity to carry the paint to the handpiece, or by an enclosed paint pot with a regulating valve and pressure applied to the surface of the paint by compressed air. In some situations all that is required is an overhead paint pot, the weight of the liquid feeding it to the handpiece. An enclosed paint pot has the very great advantage that (with a proper valve) the feed of the paint can be regulated to a nice degree. The paint pot shown in Fig. 77 has a damped cover which is capable of being quickly removed, and a low-pressure feed to the paint is obtained from a reducing valve. This can be set so that the paint can be forced to the handpiece to secure a uniform flow whether the paint be thick or thin.
The Exhaust Installation.
We next reach the question of arranging a satisfactory form of exhaust installation, which has been found to be absolutely essential in order to insure the health of the operator.
This exhaust question obviously opened up special problems in the direction of convenient forms of hoods or work benches, so arranged as to carry away the fumes created by the paint distributor without unduly inconveniencing the operator by reason of the draught set up.
By some firms use is made of the exhaust to collect the residue or surplus paint drawn off by employing a ventilator, which sets up a medium pressure, and interposing between the outlets of the hood and the air shaft some form of perforated screen or screens which are readily removable, or in some cases revolvable and self-cleaning.