There are literally hundreds of different kinds of valves. Each and every one does one thing the same; they stop the flow of a liquid or gas. However, their appearances, designs, modifications, and means of operation are all very different. In addition to the standard differences, these objects are made from different materials, too.
Most valves are now predominantly made of stainless steel, but you may come across an iron or copper valve from time to time as well. To get a really good idea of all of the available stainless steel valves you can use for varying purposes in your factory, here is a sampling of some of the more unusual ones and how they operate.
Double Union Threaded Pressure Regulator
This stainless steel valve looks like an inverted capital "T" with an inverted drinking cup in the middle. It is used to control fluids and gases through a line or through two lines. A single line can be connected and extended by this valve between two sections of pipe or hose, or two separate lines can meet in the middle and run into another pipeline or hose out the back of the valve. The "inverted cup" portion is your pressure regulation device. It prevents excessive pressure from building up in the line(s).
Stainless Steel Valve and Float Assembly
If you were to lift the lid off the tank of your toilet, you would see something that plumbers call a "float." It appears to be an inflated balloon-like structure that "floats" on top of the water in the tank. It controls the flow and the level of water in the tank.
This stainless steel valve version of your toilet float assembly has some remarkable differences from your toilet float assembly. It incorporates a completely hollow, steel "float", which is attached via a long stainless steel "arm" to a valve. Your toilet assembly does not have a valve or a steel "float"; it has a flush handle where the valve is, and a hollow rubber float where the steel float is. The stainless steel valve and float are frequently used in wine and beer production to monitor gas from yeast, and gas from the fermentation cycles.
Stainless Steel Electric Solenoid Valves
If the thought of electricity and a valve coming together makes you uneasy, it should. However, these valves are typically rigged for automated assembly lines and rarely used with liquids. They are more commonly used for gases and control of automated and measured amounts of gases.