Davey HS50 Mechanical Seal

The Davey HS50 pressure pump takes a mechanical shaft seal for a 5/8″ shaft (about 15.9 mm). Davey’s part number for this seal is 49771SP, and this CapacitorsNZ seal is an aftermarket replacement for it. The same seal is listed for the Davey HS60 and a number of Silensor models, so check the size of your old seal before fitting.

Which pumps use the same seal as the Davey HS50

This seal is not unique to the HS50. Besides the HS50, it is also listed for the Davey HS60, Silensor SLS75, Silensor SLS100, Silensor SLS150, Silensor SLS200, Silensor SLS300, Silensor SLL150, Silensor SLL200, Silensor SLL300 and Silensor SLL400. It also suits the Davey HS60-08 and the Davey ProMaster, which don’t have their own pages.

The seal is also sold on its own as our 5/8″ seal to suit Davey HS50, HS60, Silensor and ProMaster pumps. Parts for other models are under Davey service kits.

Signs the seal on a Davey HS50 has failed

A mechanical seal wears slowly and usually announces itself before it lets go completely. On a pressure pump like the HS50, look for:

• water dripping or weeping from the gap between the pump body and the motor
• the pump cutting in for a few seconds when no tap is open, as the system slowly loses pressure
• a damp patch, mineral crust or rust streak under the motor end

Fitting a 5/8″ seal to the HS50

Turn the power off at the isolator and release the pressure before you start. A mechanical seal comes in two halves: a stationary seat that presses into the pump housing, and a spring-loaded rotating head that slides onto the shaft behind the impeller. Replace both halves together, never one old half with one new half.

Handle the seal by its edges and keep the polished faces clean and free of fingerprints, wet the rubber parts with a little soapy water to help them slide home, and never run the pump dry once the new seal is in. A 5/8″ shaft is close to 16 mm but is not the same as a 16 mm metric seal, so measure the shaft rather than guessing.

Before you order

Check the old part before fitting: match the size of your old seal.

Capacitor details for this pump: Davey HS50 capacitor guide.

What seal fits a Davey HS50?

The Davey HS50 takes a mechanical seal for a 5/8″ shaft. This CapacitorsNZ aftermarket seal replaces Davey part 49771SP.

What is the Davey part number for the HS50 mechanical seal?

Davey's seal number for the HS50 is 49771SP. This CapacitorsNZ seal is an aftermarket replacement for 49771SP, to suit the Davey HS50.

Does the Davey HS60 use the same seal as the HS50?

Yes. The Davey HS60 is listed with the same 5/8″ seal as the HS50 (replacing Davey 49771SP), as are the Davey Silensor SLS75, SLS100, SLS150, SLS200, SLS300, SLL150, SLL200, SLL300 and SLL400.

What shaft size is the Davey HS50 seal?

The Davey HS50 seal is for a 5/8″ shaft, which is about 15.9 mm. Measure your shaft or old seal to confirm before fitting.

Can I replace just the seal on my Davey HS50?

Yes, the seal to suit the Davey HS50 is sold on its own. If the run capacitor is also getting old, the service kit to suit the Davey HS50 bundles the seal and capacitor for less than buying both separately.

Is this seal made by Davey?

No. It is an aftermarket CapacitorsNZ seal made to suit the Davey HS50 and replace Davey 49771SP.

What if it doesn't fit?

If you're unsure, send us a photo of your old part and the pump's label before ordering.