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MB-II Technical Data
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THE
UTEX SEAL THAT KEEPS YOU PUMPING LONGER
The unique MB-II can be operated as either a double or tandem
seal, both of which are hydraulically balanced, making it one of the
most versatile seals available. It is designed and built to reduce and/or
eliminate fugitive emissions and to increase mean time between planned
REPAIRS (MTBR).
The dual stationary bellows assembly self
adjusts for misalignment and reduces the potential for harmonic
vibration. The extremely low mass of the face and bellows assembly
improves face tracking characteristics during operation.
The buffer fluid is sealed on the O.D. of
the outboard bellows. This prevents heat related problems resulting from
air entrapment and dead fluid zones. Also, higher buffer fluid pressures
are attainable. A tangential flow pumping ring produces a high performance
flow of buffer fluid for efficient cooling and helps prevent abrasives
from settling in the seal cavity.
The MB-II fits ANSI pumps without
modification. Temperature range is from -75ºF to +400ºF (-60ºC to
+204ºC)
depending on the o-ring material chosen. Maximum pressure differential
is 300 psi (20 bar) across either bellows, with speeds up to 4500 fpm
(23 m/s).
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| Part |
Materials |
| Bellows & End Fittings |
Hastelloy C-276 bellows core.
316 SS standard end fittings, Hastelloy C available. |
| Metal Parts |
Standard - 316 SS metal parts.
Available - Hastelloy C and Alloy. |
| Stationary Seal Face |
Standard - CNFJ-B grade
carbon.
Available - Tungsten carbide and silicon carbide. |
| Rotating Seal Face |
Inboard
Seal - Alpha sintered silicon
carbide.
Outboard Seal - Reaction bonded silicon carbide. |
| O-Rings |
Standard - Viton
Available - EPDM, Neoprene, Nitrile, Chemtex, Aflas, Chemraz, Kalrez, PTFE,
and encapsulated Viton. |
| Parameter |
Operating
Range |
| Temperature |
-75°F to
+400°F (-60°C to +204°C)
depending on o-ring material chosen. |
| Max.
Pressure Differential |
300 psi (20 bar) across either
bellows |
| Maximum
Stuffing Box Pressure |
Double Mode - 275 psi (19 bar)
Tandem Mode - 300 psi (20 bar) |
| Maximum
Buffer Pressure |
Double Mode - 300 psi (20 bar)
Tandem Mode - 275 psi (19 bar) |
| Speed |
Up to 4500 fpm (23 m/s) |
| Notes |
INLET/OUTLET
CONNECTION SIZES:
¼" N.P.T. for seal sizes 1" thru 1 ½"
3/8" N.P.T. for seal sizes 1 5/8" thru 2 ¾" |
MB-II Features and Benefits
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Features |
Benefits |
| 1.
Unitized construction of welded bellows assembly. |
1.
Fewer parts, even face loading, uniform linear spring action. |
| 2.
No dynamic O-rings. |
2.
Fretting corrosion is eliminated since the O-rings are not required to
flex or roll to maintain sealing; the seals cannot become immobilized if
the O-rings swell or char when exposed to aggressive solvent or heat;
Viton encapsulated O-rings can be used throughout the seal. |
| 3.
Bellow's core is Hastalloy C-276 as standard. |
3.
Improved stress corrosion resistance, wider range of chemical
resistance. |
| 4.
Pumping ring is standard. |
4.
Provides positive flow of buffer/barrier fluid, better heat dissipation
compared to thermal convection. |
| 5.
The entire outboard bellows seal is inside the outboard seal gland
cavity, with the fluid on the seal O.D. |
5.
More stability and reliability, eliminates the following problems
associated with i.d. pressurized outboard seals: air entrapment that can
cause dry running; "dead zones" of uncirculated fluid that can
overheat and cause loss of lubrication abrasive wear due to particles
being thrown into seal faces by centrifugal force; low pressure capabilities
(typically less than 150 psi). |
| 6.
Stationary bellows design on both inboard and outboard seals (currently
a UTEX exclusive feature). |
6.
Self-aligning, lower emissions in ppm, adjusts for stuffing box
misalignment without bellows fatigue, requires no vibration dampeners
which can cause face hang-up or fretting, eliminates viscous drag
on the bellows, can be used in more viscous products. |
| 7.
Inboard bellows seal is double balanced. |
7.
Operates in either a dual pressurized or non=pressurized seal. |
More Technical
Information About the MB-II
Available MB-II Dual Cartridge Seals
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