Metal bellows mechanical seals feature a bellows core made of one of several types of bellows. The most common are AM350 and Hastelloy C. Usually with Stainless Steel end fittings permits these pump seals to be used for services beyond the range of pump seals with synthetic rubber sealing members.
Typical applications include: cryogenics, heat transfer fluids, severe chemicals and corrosives at temperatures from —350° to +650°F (—212° to +343.33°C) with standard seal construction. (For higher temperatures—our engineering department.)
Metal Bellows Mechanical Seals Design Features
1. Wide service range from cryogenics to heat transfer liquids and corrosive chemicals.
2. Long service life—only one moving part.
3. Flexible bellows construction eliminates seal hang-up due to solids or dirt in pumpage.
4. Metal sealing wedge eliminates temperature restrictions of elastomers or plastics.
5. Built-in hydraulic balance eliminates step in shaft or sleeve*.
6. Available for either inside or outside mounting.
7. Stabilizer tabs prevent possible damage due to vibration and excessive shaft run-out.
Nested Ripple design with advanced welding techniques insures maximum bellows strength and fatigue resistance. It all but eliminates stick-slip failures.
Hastelloy "C" is used in both the MB and the MBFG bellows. It is far superior to 316SS, AM350, and Alloy 20 in corrosion resistance, stress corrosion cracking resistance, and yield strength. Alloy 20 has a yield strength of 35,000 psi while Hastelloy C has a yield strength of 58,000 psi, a 66% increase! That is where it counts; in the bellows.
Drive set screws are Hastelloy "C" on both the MB and MBFG Hastelloy "C" set screws reduces galling problems that result with 316SS set screws. The 66% greater yield strength also insures that your Allen wrench will not "strip out".
Metal bellows pump seals will not fret the shaft or sleeve because it has no dynamic (sliding) "0" ring. All pusher seals (seals with springs) have dynamic "0" rings. This means that you can mount either metals bellows seal directly on the shaft and save the cost of a sleeve.
Because the bellows spring does hot have to overcome "0" ring friction drag, as does the pusher seal, the spring load can be lighter in the MB and MBFG pump seals bellows then in the pusher seal design. Some common pusher seals have spring loads of 35 to 45 psi, while the metal bellows load is approximately 25 psi. This can result in up to a 50% decreased seal face wear rate. The bellows produces even face loading, superior face tracking and less frictional heat.
Balance: balance diameter lies within the bellows itself. This
provides the ability to handle pressures to 300 PSI
Metal bellows pump seals are also made into single and double cartridge configurations.
If you have any questions please contact us at: E-Mail about your pump seals applications.
Phone: 714-593-9780 Fax: 714-593-9701