Pressure Compensating

Here's some information from Neoperl on how pressure compensating products, such as many of our shower heads and aerators, work:

A pressure compensating product maintains a constant flow regardless of variations in the line pressure therby optimizing system performance and comfort of use at all pressures.

 Dynamic conditions (flow): 

The o-ring subjected to the line pressure is compressed into the seating area which reduces the water passage (position 2).

As the pressure increases the o-ring is compressed further into the seating area and reduces the water passage further (position 3).

As the pressure decreases the o-ring relaxes and reopens the water passage (return to position 2 and 1). Pressure compensating flow regulators are not recommended for use in non-pressurised applications.