How does a piston work?

Cup and flanged plungers
	Cup and flanged plungers work in the same way:
	For the plunger to be effective, it must have a snug fit between the edge of the object to be plunged and the sealing edge of the plunger.
	Tightness is achieved by tilting the piston when entering the water. This will remove all air from the piston cup and ensure that the cup is filled with water.
	Water cannot be compressed, but air can. If there is air pressure under the cup, it can compress, causing air to escape and flow out from under the sealing lip of the plunger. This will break the seal between the plunger and the blocked object, rendering any dipping effort ineffective.
	When a good seal is achieved, water is forced onto the blockage as the piston is pushed down by hand.
	Since water does not compress under pressure, the water pressure increases each time the piston is pressed.
	However, when the piston is pulled up (backward), the pressure on the water is reduced so that the water is at low pressure.
	The up and down movement of the plunge places the water under high and low pressure at a constant rate.
	Changes in pressure push and pull the blockage, breaking it up and moving it away from the pipe walls. This gravity-assisted action helps unlock the pipe, allowing water to drain.
suction plunger
	The suction plunger is slightly different from the cup or flange plunger. This type of plunger is not cupped to trap air when submerged in water.
	Thanks to the flat head, it can be inserted into the toilet bowl without trapping air (so there is no need to insert it at an angle) and form a seal easily.
	As the suction plungers plunge up and down in the toilet trough, they force water into the blockage at high and low pressure. The pressure will break up the blockage or push it down the drain, allowing the water to flow freely again.