Gear Pump Seal Failures
Gear Pump Seal Failures
(OP)
Hello everyone,
I have been stumped by a series of mechanical seal failures on a gear pump.
Fluid:
Printing Ink
200 Degrees F Max
200 cps max
No solids present
Pump:
Gorman Rupp Internal Gear
Model GHA3NM3-B
Driven at 205 RPM with 5 HP Gearmotor
30 GPM @ 100 PSI
Mechanical Seal:
Single Internal Unbalanced Pusher
316SS spring and carrier
Stationary Face: Silicone Carbide / Viton oring
Rotating Face: Silicone Carbide / Viton boot
Seal assy cut sheet:

System:
Truck Loading
500 Gal Tank feeds suction with 2' run of 3" pipe directly to suction. No elbows. Discharge through filter assy to truck.
Problem:
Viton boot is shearing between rotational face and carrier. It appears that the seal faces are sticking together. The boot and carrier are rotating as they should, but the face doesn't want to rotate and the resulting torque is shearing the viton boot. This failure has occured five times on five different pumps. There is no sign of abrasion anywhere. There is no sign of chemical attack. There is no sign of excessive heat.
Manufacturer has no answer. My mechanical seal vendor has no answer. I think a positive drive is needed between carrier and seal face, maybe by means of a pin. Right now, the arrangement is a friction drive, in which torque is transmitted to the rotating face via a compression fit between carrier and viton boot.
Any ideas? Pictures below:

Failed Boot

New Seal Showing Carrier / Face Arrangement
I have been stumped by a series of mechanical seal failures on a gear pump.
Fluid:
Printing Ink
200 Degrees F Max
200 cps max
No solids present
Pump:
Gorman Rupp Internal Gear
Model GHA3NM3-B
Driven at 205 RPM with 5 HP Gearmotor
30 GPM @ 100 PSI
Mechanical Seal:
Single Internal Unbalanced Pusher
316SS spring and carrier
Stationary Face: Silicone Carbide / Viton oring
Rotating Face: Silicone Carbide / Viton boot
Seal assy cut sheet:

System:
Truck Loading
500 Gal Tank feeds suction with 2' run of 3" pipe directly to suction. No elbows. Discharge through filter assy to truck.
Problem:
Viton boot is shearing between rotational face and carrier. It appears that the seal faces are sticking together. The boot and carrier are rotating as they should, but the face doesn't want to rotate and the resulting torque is shearing the viton boot. This failure has occured five times on five different pumps. There is no sign of abrasion anywhere. There is no sign of chemical attack. There is no sign of excessive heat.
Manufacturer has no answer. My mechanical seal vendor has no answer. I think a positive drive is needed between carrier and seal face, maybe by means of a pin. Right now, the arrangement is a friction drive, in which torque is transmitted to the rotating face via a compression fit between carrier and viton boot.
Any ideas? Pictures below:

Failed Boot

New Seal Showing Carrier / Face Arrangement





RE: Gear Pump Seal Failures
If the product could withstand a tiny bit of contamination, a fingerprint of silicone grease on the seal faces might keep them from sticking until they've become accustomed to each other. Again, not that I know much about mechanical seals...
Mike Halloran
Pembroke Pines, FL, USA
RE: Gear Pump Seal Failures
Ted
RE: Gear Pump Seal Failures
Ted, I don't think this is happening but I will check, interesting point. The clearances are very tight within the seal chamber so it is a possibility, but I saw zero signs of wear on the shaft. If it was contacting the seal chamber wall it would also be contacting the shaft.
Perhaps I should have posted this in the mechanical seal engineering forum.
RE: Gear Pump Seal Failures
RE: Gear Pump Seal Failures
The only reason we put mechanical seals in our paint pigment pumps was because of the abrasive solids. If the ink has no solids, see if there anything preventing you from experimenting with a lip seal or two.
Charlie
www.facsco.com
RE: Gear Pump Seal Failures
RE: Gear Pump Seal Failures
Unusual to have similar materials on the rotating and fixed seal. Normally have a ceramic or stainless fixed seal face with the silicon carbide rotating.
A spray of light oil or WD40 on the faces before @first run' will help to 'bed' the faces in.
Offshore Engineering&Design