- A spray gun, or water pistol, is a hand-held, plastic backyard toy that kids use in water battles and water games. There are also spray guns used for home improvement, for applying caulking and distributing paint. The same pumping spray gun device is used for everyday household sprays and cleaners. A spray gun always contain a trigger, a reservoir and a liquid, and it requires pumping action for results.
- A spray gun works in the same way an oil rig pumps oil and your heart pumps blood--with a pulsing buildup of pressure and an ejection of the stored liquid through the nozzle. A child's spray gun has a small plastic stopper on the top end of the gun barrel that is removed for filling the gun with water and then replaced when full. The trigger is attached to a piston and spring in the handle's pump. When the trigger is squeezed, the piston squishes back into the shrinking cylinder area, forcing out any water that is in the cylinder to spray out the nozzle. When the trigger is released, the piston stretches back out, drawing water up from the reservoir below through a small plastic tube with a one-way valve at the top. The water collects in the cylinder, ready for another spray.
- The one-way valve is what makes a sprayer shoot the water forward out of the nozzle and not back down into the reservoir when the trigger is squeezed. At the top of the plastic collection tube is a small plastic ball that lies against a seal at a slight angle. When the trigger is squeezed, the water pressure holds the ball against the seal, blocking off the chance for the water to escape back down the tube. The water can only move forward, out the open nozzle hole. When the trigger is released, the expanding cylinder inside the gun creates a vacuum, forcing fresh water to be sucked up through the tube, which also sucks the ball up, allowing the water to flood the barrel. When the trigger is pushed again, the ball is forced back down against the seal, and the newly trapped water is ejected forward, out the nozzle.
