Graph of how Diamond Faced Seals compare to Standard Faced Materials
Why use Diamond Coatings?
Diamond’s material properties provide advantages for seal faces
- Diamond is the hardest known natural material
- –Wear resistant
- Low friction characteristic based on grain structure
– Dry run tolerance
– Low break-out torque (dry)
- High Thermal Conductivity
– Transfer seal face generated heat
- Chemically resistant in acids, alkalines, and solvents
–More resistant than any typical seal ring material
Diamond-like Carbon (DLC) is used on magnetic drive pump bearings
- An amorphous carbon material applied over a silicon carbide base material that provides an “elastic” effect of polishing without galling
- Useful for incidental dry running contact at startup and shutdown with hard on hard gas seal faces
Examples of Pump failure with Standard Bearings
Ultrananocrystalline Diamond-Coated is used on mechanical seal faces
Seal face materials have always been challenged to provide reliable operation in low lubricity fluids. In the past, this challenge was addressed by lubricating seal faces with a cool, clean external fluid. Although effective, this solution adds operating cost throughout the life of the seal. Alternatively, dual seals operating on clean barrier fluid offer longevity with lower operating cost, but higher initial cost for the required support system. The ideal answer for seal users is mechanical seals lubricated directly by the process fluid. UNCD coated silicon carbide as a seal face material enables Flowserve to offer improved reliability in poor lubricating fluids without additional controls.
Features and Benefits
- The lowest friction of any seal face material provides cool running seal faces in poor lubricity fluids such as hot water
- Bonding the hardest known material to the seal face running surface gives maximum resistance to abrasive particle damage
- The highest chemical resistance of all seal face materials enables its use in aggressive acids, alkalines, and caustics
- High wear resistance brings forgiveness for off-design operation such as intermittent dry running • Fine grain nanocrystalline diamond allows operation against all common mating face
- Materials including carbon, silicon carbide, tungsten carbide, and itself.
- Certification of biocompatibility per USP Class VI is available.
Providing solutions for challenging applications
- Low wear
– Intermittent dry running
loading and unloading applications
- High hardness
– Three-body abrasion on seal face running surface
Silicon carbide scoring and binder pullout can be eliminated
- Reduced friction
– Low lubricity fluids
- USP Class VI tested and approved
Test Result – Partial Dry Running with Water
ISC2 1.875 dry run testing @ 4,800 rpm
- Enlarged bore seal chamber with residual water
- Maximum temperature reached after 90 minutes was just 85°C (185°F)
– 108 times longer than SiC vs SiC under the same conditions @ 3,600 rpm
Two Applications where UNCD has proved successful.
Wastewater treatment plant ran UNCD dry for 2 hours with no the detriment in sealing performance
- The seal continues to operate, extending the pump’s reliability by over 5x the competitor seal.
Alumina plant retrofitted SLC seals with UNCD for tough slurry service
- Reliability was increase from a few weeks with traditional face materials to exceeding the life of the pump’s wear components
- The customer was thrilled and has install UNCD on numerous additional applications, all very successful
To find out more contact Phil Soltan, our pump specialist to discuss this further on 021 461 7260
You might also be interested in our Diamond Coated Silicon Carbide Faces for Pump Seals – Standard Cartridge Seal ISC2 series