Mechanical seals for liquid ring vacuum pumps

What it does inside the pump

The mechanical seal closes the gap where the shaft passes out of the casing into atmosphere. Unlike a pump handling only liquid, a liquid ring pump asks the seal to work against vacuum on one side for part of its life, so the seal has to stay closed when the pressure differential reverses, and it needs its flush to be present before the pump starts.

How it fails, and what you see first

The two failure modes we see are dry running and chemical attack. Dry running — a flush line that was valved off, or a pump started before the seal chamber filled — cracks the carbon or the silicon carbide face in seconds, and the tell-tale is a radial crack visible on the stationary face. Chemical attack softens or swells the elastomer, usually the O-ring behind the rotating face, and the seal then leaks steadily rather than failing suddenly. Crystallizing services glue the face to the seat while the pump is stopped, and it shears on the next start.

What to send us so the part is right

Model, serial, shaft diameter at the seal, and whether the machine is single or double (double seals need a barrier fluid pressure and the plan number). Give the process gas, the seal liquid and its temperature so we can pick the face pair — silicon carbide against silicon carbide for abrasives, carbon against silicon carbide for clean duty — and the elastomer, FKM or FFKM.

Which models take this part (273)

Grouped by pump family. Model numbers in blue have their own page with the full specification table; the rest are supplied from the same frame — send the model and we confirm against the drawing.

Other parts for the same machine

Request a Quote Order parts by model → Full parts catalogue