Mechanical seal john crane
Type 7848
Modular Wet- or Dry-running Cartridge Seal for Mixer and Agitator Applications – Type 7848
Type 7848 is part of the 7800 Vessel Seal family. The 7800 family consists of heavy-duty, dual pressurized, back-to-back, pusher cartridge seals designed for mixing and agitating equipment. This flexible seal family incorporates modular hardware to provide maximum interchangeability and is available in four different configurations (7828G, 7828GD, 7848W, 7848D), which are specified by the applied seal face technology. Type 7848 is characterized by the use of standard wet seal and special dry running seal faces technology. For details on the non-contacting gas seal versions, please see product description of seal Type 7828.
Type 7848 is available in two variants. The Type 7848W is a conventional wet-running seal that needs an external liquid for lubrication, whereas the 7848D is using special dry-running face materials that allow for application of a gas as barrier fluid. Advantages of contacting dry-running seals include freedom from contamination by barrier liquid at a low face wear rate together with a cost-efficient, easy-to-install (gas) supply system. Wet seals usually can cope with higher pressures and speeds and are less susceptible against solids. Type 7848 is therefore a perfect solution for general purpose and heavy-duty applications.
The 7800 Vessel Seal family was originally developed for the North American market. Therefore, all measurements follow imperial units, and standard designs are available for inch-sized agitator shafts from 1.000″ to 5.000″. Adaptations to interim or metric-sized shafts are available on request. The Type 7800 Series generally accommodates large amounts of radial run-out. Therefore, an integrated radial bearing is only available as an option for additional shaft stability. For protection against product contamination by barrier fluid or wearing face particles, a debris well option is available.
Product Description Type 7848
The Universal Vessel Seal 7800 Series is a modular cartridge seal for use in a wide variety of mixing and agitating equipment and covering a broad application range. The 7848D and 7848W are dry running and wet running heavy duty cartridge double seals. The Universal Vessel Seal uses modular hardware which provides maximum interchangeability. Four combinations of seal face technology provide the user with unmatched flexibility and value.
- Type 7848D is the latest proprietary face materials are used in a dry nitrogen barrier where seal faces exhibit virtually no wear. Robust drive system minimizes primary ring to hardware contact – eliminating seal face hang up while creating a highly flexible seal head. The seal is reverse pressure balanced and will remain closed in the event that barrier gas pressure is lost. Materials of construction are FDA approved.
- Where process or application conditions require a liquid barrier, the 7848W is a heavy duty cartridge double seal that is liquid lubricated. The 7848W uses hardware which is identical to the 7848D. All materials are FDA approved
Table Parameters Type 7848
| Temperature Limits | -40°F to 400°F/-40°C to 205°C
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|---|---|
| Pressure Limits | Vacuum to 210 psi(g)/14.5 bar(g)
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| Speed Limits | Dry: 400fpm/2m/s
Wet: 5000fpm/25m/s
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| Size Limits | 1" to 5"
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| Runout Limit | 0.125" TIR/3.18mm TIR
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Features Type 7848
- California Residents: PROPOSITION 65 WARNING
- Dual-pressurized cartridge seal for steel vessels
- Back-to-back seal arrangement with balanced faces
- Liquid-lubricated (7848W) or contacting dry-running (7848D) face options available
- Reversed pressure capabilities inboard
- Accommodates large amount of radial shaft run-out
- Bearing option available
- Debris well options available
- Broad range of material option include FDA or USP compliant materials
- Standard design for inch-sized agitator shafts (1.000″ – 5.000″)
- Special designs, interim or metric sizes and material options on request
- Axial movement: 0.093″/2.36mm max.
- Out of square: 0.003″ max.
- Angular deflection limit: 2.41 degrees
Recommended Applications Type 7848
- Mixer and agitators
- Other rotating equipment