f. Open air motor needle valve

TM 5-4940-228-14 NOTE Air nozzle was removed to prevent paint build up inside while spraying without air. f. Open air motor needle valve slowly while watching motor shaft, keep opening air motor nee- dle valve until a slow motor shaft rotation is ob- served (Fig. 2-3), This will keep your paint stirred continuously while you are spraying. g. Adjust spraying pressure air regulator to 20 psi as indicated on spraying pressure air gage (Fig. 2-3). h. Pull trigger on spray gun while alternately adjusting spraying pressure air regulator and fluid pressure air regulator until satisfactory spray is ob- tained. i. Adjust fan control to obtain desired width of spray pattern (Fig. 2-4). NOTE For proper operation, keep atomizing air pressure as low as possible. Proper fluid pressure depends on type of paint, viscosity, length of hose, height of spray gun above tank, and desired speed of application. Experimentation on the part of the operator will be nec- essary to obtain the best combination of pressures and adjustment settings when becoming familiar with equip- ment and when spraying different ma- terials. Paint should atomize into fine particles which do not splatter against painted surfaces, but flow to- gether to produce an even coat. j. Hold spray gun six to twelve inches (15 to 30 cm) from work and at right angles to surface to be painted. Point spray gun directly at work, pull trig- ger and move spray gun at a steady speed. The stroke should be started before trigger is pulled and the trigger released before the end of each stroke (Fig. 2-7). Overlap each stroke by approximately one third the width of the fan. NOTE Slight pull on trigger emits air only which can be used for dusting. Pull trigger all the way back when paint- ing. k. If an area is inconvenient to reach with the spray gun, it will be necessary to attach the nozzle extension as follows (Fig. 2-4): (1) Turn handle on fluid pressure air regu- lator and spraying pressure air regulator counter- clockwise (Fig. 2-3). (2) Open slide valve to relieve pressure on the pressure (paint) tank. Wait for pressure to exhaust from tank and observe pressure gages for “0” read- ing before proceeding (Fig. 2-3). (3) Remove air nozzle by hand and fluid noz- zle with an 11/16 inch (17.46 cm) open end wrench (Fig. 2-3). (4) Inspect fluid nozzle gasket for tears, cracks or damage. Replace, if necessary. (5) Attach fluid extension to spray gun head; next, slide air extension over fluid extension and lock in place with lock ring. (6) Adjustments and operation are the same as spraying with the spray gun alone. l. To spray small quantities of paint, connect pressure cup to spray gun as follows (Fig. 2-4): (1) Remove black fluid hose from spray gun head. (2) Remove 1/8 inch (3.18 cm) pipe plug next to air connection at spray gun handle. (3) Remove pressure tube from pressure cup and install 1/8 inch (3.18 cm) pipe fitting end into spray gun handle. (4) Attach pressure tube to pressure cup. (5) Attach pressure cup assembly to fluid con- nection on spray gun. (6) Mix and strain paint thoroughly, so that it is free from lumps, skins, and foreign matter before pouring it into cup. Paint should be at hand-brush- ing consistency. Screw cup into cover assembly. (7) Adjust spraying pressure air regulator on pressure (paint) tank to 20 psi. Pull trigger and ad- just fluid control for satisfactory spray; adjust fan control for desired spray width. Higher pressure may be required. WARNING Do not exceed 45 psi in the pressure cup. Cup could burst and cause injury to operator. NOTE Spray with same techniques as used with spray gun alone. 2-9