What's different inside a new RP spray gun.

What's Different Inside A New RP Spray Gun

Here's a first detailed look at the inner workings of an innovative airless, internal-mix spray gun for reinforced-plastics laminating and gel coating that was just introduced at NPE in Chicago (see PT, June '91, p. 105 for previous discussion). The new Pro Gun from Venus-Gusmer of Kent, Wash., incorporates novel approaches to mixing and valving that are said to improve performance and reduce maintenance.

NEW MIXING DESIGN

The Pro Gun's new "Distributive Mixing" approach involves injecting resin into the mixing chamber from several holes surrounding a central catalyst port (see bottom diagram). This concentric design reportedly creates a more balanced flow for more thorough mixing than in previous designs. The result is that users may be able to reduce catalyst levels slightly, and pumping pressures can be somewhat lower than in the past, which may reduce styrene fuming, says marketing manager John Raymer.

NO MORE

NEEDLE

VALVES

Lead/lag off-ratio problems are now said to be eliminated by the Pro Gun's new valving system (see diagram). There are no more needle valves to adjust; instead, the gun has a concentric stainless-steel rod and cylinder with two parallel holes through their diameters. When the gun's trigger is pulled, the center rod rotates relative to the outer cylinder, bringing the holes into alignment and opening a clear channel for resin and catalyst. When the trigger is released, the holes in the rod and cylinder no longer align and flow stops instantly. This system mechanically ensures that flow of resin and catalyst start and stop perfectly simultaneously.

The new gun reportedly also is lighter and easier to operate than the H.I.S. 80 gun, which it replaces - at the same price. (CIRCLE 1)

Incidentally, Venus-Gusmer recently came out with a new Pro Series Multicolor Gel-coater, compatible with both the new Pro Gun and H.I.S. 80. The unit uses uncharged accumulators and a single catalyst pump that can be moved quickly among as many as four gel-coat pumps with the aid of quick-connect hoses. (CIRCLE 2)

PHOTO : (Above) Forget about adjusting needle valves and lead/lag problems. Venus-Gusmer's new Pro Gun uses a concentric rod and cylinder with holes drilled through them for resin and catalyst passages. Both flows start and stop instantly and simultaneously when the center rod rotates, depending on whether its holes align with those of the outer cylinder.

PHOTO : (Right) Improved mixing is said to be created by the concentric arrangement of a center catalyst port and multiple resin ports in the gun's mixing chamber. As a result, spray pressures can be reduced, and so can styrene fuming, the company says.