Burks 20500-C Mechanical Seal 1.250 in Shaft
The Burks 20500-C seals the shaft where it leaves the pump casing. It is a mechanical face seal using Carbon, Ni-Resist and Viton, for a 1.250 in shaft - a spring-loaded rotating face running against a stationary seat, self-adjusting as the faces wear.
A mechanical seal is a wear part with a finite life. The carbon face is sacrificial and slowly gives itself up against the harder seat, and the spring takes up the wear until it runs out of travel. What ends most seals early, though, is a dry start, a starved suction line, or grit carried through the faces. The warning is usually a drip that appears after shutdown and then becomes constant.
Shaft size and elastomer both have to match. This seal is built for a 1.250 in shaft, and the Carbon, Ni-Resist and Viton specification sets the temperature range and the liquids it will tolerate. Burks lists the same shaft size in several compounds, so confirm both before ordering.
Key Features
- Genuine Burks mechanical shaft seal assembly
- 1.250 in shaft - matches the original shaft dimension
- Carbon, Ni-Resist and Viton construction
- Direct replacement for the original Burks seal
- Spring loaded and self-adjusting as the faces wear
- Supplied complete - rotating face, seat and elastomers
Applications
- Burks pump rebuilds and overhauls
- Curing a persistent drip from behind the pump casing
- Recovery after a dry run or a lost prime
- Replacing seal faces scored by grit or abrasives
- Planned maintenance on duty and standby pumps
- Industrial, marine and dockside pump installations
Specifications
- Brand: Burks
- Manufacturer: Crane Pumps and Systems
- Manufacturer Part Number: 20500-C
- Part Type: Mechanical shaft seal
- Material: Carbon, Ni-Resist and Viton
- Size: 1.250 in shaft
- Condition: New
Frequently Asked Questions
Q: Can I touch the lapped faces while fitting it?
Keep your fingers off them. The faces are polished to within a fraction of a light band and skin oil or a single hard particle left on them will hold them apart. Wipe with a clean lint-free cloth, use the recommended lubricant, and press home with even pressure.
Q: Should anything else be changed at the same time?
Check the shaft or sleeve where the elastomer grips it. A groove worn at the old seal position will chew the new boot in short order. The casing joint seal is also worth renewing, since it has to come off to reach the seal anyway.
Q: How long should a mechanical seal last?
Years on clean liquid with a flooded suction. Life falls sharply with abrasives, with frequent starts on a starved inlet, and with temperatures near the top of the elastomer rating. Most premature failures trace back to operating conditions rather than the seal itself.
Q: A few drops appear when the pump first starts. Is that normal?
A very light initial weep while the faces bed in can settle within an hour or so of running. A steady drip, or anything that continues beyond that, means the faces are not seating and the seal needs to come back out.
Not sure this is the right part? Send us a Picture of the pump plate on your pump and the CLR Marine team will confirm the correct mechanical seal before you order.
CLRMarine
