HPLC pump maintenance

In order to change the piston seal you must first remove the head. In some pumps the head is coming out of the pump and then you must dismantle it. In some others you just unscrew the two hex screws and you remove the cover.

 Keep always in mind that the piston is also inside the head and it is very delicate. 

There are seals used for aqueous solvents usually they are yellow, and seals used for organic solvents (black)

In most of the pump  there is also an outlet filter that needs to be cleaned  because it sometimes gets clogged. Rinse it with an alcohol or place it in the ultrasonic bath for 5 minutes. 

The piston itself doesn't need anything else besides attention while dismantling the head and some rinsing with alcohol.