Replacement mechanical seal for Monolobi 60 Chiaramello honey pump

01 · WHY IT FAILS

Rarely age: usually a spell running dry

A mechanical seal is two flat faces turning against each other with a thin film of product between them, and that film does two jobs at once: it seals and it cools. On the Monolobi both faces are tungsten carbide —widia— instead of the ceramic-graphite pair used on simpler pumps: a much harder material, and less sensitive to the sugar crystals in honey.

What it will not take is running without product. With the pump turning dry, nothing carries the friction heat away, the temperature climbs fast and the seal is gone. That is why the golden rule for this pump —watch the source tank and stop before it runs out, not after— is what decides how long this part lasts.

02 · HOW IT GOES IN

Two parts, three screws and a tooth that leaves no room for guessing

The rotating part goes onto the shaft and is held by three screws. It is itself made of two pieces: the one carrying the carbide face is assembled onto the springs, compressing them, and that compressed spring pack is what afterwards keeps the two faces pressed together while the pump runs.

The fixed part sits in the pump chamber: it has a slot that drops into its seat and a tooth that marks the only correct position. It is the detail that gets missed in a rushed rebuild, because if the tooth does not land in place the part looks fitted and is not.

03 · THE OTHER SPARE

Heat damage rarely stops at the seal

Once the pump has run dry, the heat does not stay in the seal: the rotor and the scraper are food-grade plastic and they score or crack for the same reason. If you are opening the pump, check them before you close it —the two together are a separate spare— and replace whatever is damaged in one go. Passing a scorched rotor as good is what makes the repair last a single season.

04 · BEFORE YOU BUY

Supplied as a complete mechanical seal: fixed part, rotating part and springs.