Spray bottles are an extremely useful type of machine and an excellent demonstration of basic plumbing principles. A spray-bottle head is made up of only a few parts. It has a trigger lever, which activates a small pump. This pump is attached to a plastic tube that draws cleaning fluid from the bottom of the reservoir. The pump forces this liquid down a narrow barrel and out a small hole at the gun's muzzle. The hole, or nozzle, serves to focus the flowing liquid so that it forms a concentrated stream.  The only complex element in this design is the fluid pump, and it's about as simple as they come. The main moving element is a piston, housed inside a cylinder. Inside the cylinder, there is a small spring. To operate the pump, you pull the trigger back, pushing the piston into the cylinder. The moving piston compresses the spring, so when you release the trigger, the piston is pushed back out of the cylinder. These two strokes of the piston, into the cylinder and out again, constitute the entire pump cycle.

Atomizers convert streams of liquid into fine sprays. They’re used in everyday applications to control the amount of liquid being released and dispersed from a container. Used frequently in homes for everyday cooking and cleaning, they’re also good for a variety of other purposes. The most basic components of an atomizer are a bottle filled with liquid and a tube that connects to a nozzle. The nozzle always has a screen inside. That screen disperses the liquid particles to create a mist.