Pump Head Seal Kit — Sales and Instrument Support

High-pressure piston seal kit for HPLC pump heads. The seal rides against the reciprocating piston and is the part that actually holds system pressure, so it is a scheduled consumable in every pump regardless of make. Seals are typically a filled polymer - PTFE or UHMW polyethylene compounded with graphite or carbon - chosen for low friction against a ceramic piston rather than for hardness.

Seal life is set by three things: working pressure, how much dissolved salt passes through, and the condition of the piston surface. A pump running buffered methods at high pressure will not reach the seal life of one running organic methods at moderate pressure, and no schedule can be copied between the two.

Fitting and after

• New seals need a run-in period at pressure before they hold properly; a small initial weep is normal and should stop.
• If the piston is scored, replace it with the seal - a new seal on a damaged piston fails again quickly.
• Check that the seal wash is flowing before closing the head.

Symptoms of a failed seal

Leak or salt crust at the pump drain, pressure ripple in time with the stroke, retention times that no longer repeat, and pressure that will not hold when the pump is stopped. Flushing buffer out with water before every shutdown is the single habit that extends seal life most.