Vessel and Agitator seals | Heavy-duty Cartridge Seal for Boiler Feed Circuit Applications


Features mechanical seal Type 7848 (W, D)

  • 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

About Mechanical seal Type 7848

Type 7828 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 7828 is characterized by the use of non-contacting, gas-lubricated seal faces with unique spiral groove technology developed and patented by John Crane. For details on the wet- and dry-running versions, please see product description of seal Type 7848.

Type 7828 is available in two variants. On the Type 7828G, both inboard and outboard primary rings have spiral grooves, and are therefore operating as non-contacting seals. Where reduced barrier gas consumption is desirable, the Type 7828GD, a hybrid seal that offers a combination of non-contacting gas seal inboard and contacting dry-running seal outboard, would be recommended. Advantages of gas-lubricated seal Type 7828 (G, GD) include the non-contacting, wear- and particle-free operation, the freedom from contamination by barrier liquid together with a cost-efficient, easy-to-install (gas) supply system. This makes these seals the perfect solution for high-end pharmaceutical 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 runout. Therefore, and due to the specific non-contacting face design, the 7828 (G, GD) is able to work without integrated trust bearing. Nevertheless, a radial bearing option for additional shaft stability is available.

Design Features mechanical seal Type 7848

  • John Crane’s dry running experience and research have resulted in proprietary materials and optimized combinations ensuring superior wear characteristics even in rigorous applications.
  • Double cartridge uses common springs allowing for self adjustment to axial motion. This maintains precise face loading to both seal faces in the presence of shaft movement.
  • Optimized drive minimizes seal face to seal cartridge hardware interaction eliminating low speed hang-up.
  • Completely modular design Universal Vessel Seal offers maximum application flexibility

Material mechanical seal Type 7848

  • Face/Primary Ring Carbon —
  • Seat/Mating Ring Silicon Carbide Tungsten Carbide
  • Sleeve 316 Stainless Steel Alloy C-276
  •  Gland Plate 316 Stainless Steel Alloy C-276
  • Collar 316 Stainless Steel Alloy C-276
  • Inner Gland 316 Stainless Steel Alloy C-276
  •  Springs 316 Stainless Steel

Operating range mechanical seal Type 7848

  • Temperature Limits
    -40°F to 400°F/-40°C to 205°C
  • Pressure Limits
    Vacuum to 210 psi(g)/14.5 bar(g)
  • Speed Limits
    Dry: 400fpm/2m/s
    Wet: 5000fpm/25m/s
  • Size Limits
    1″ to 5″
  • Runout Limit
    0.125″ TIR/3.18mm TIR

Product Description Type 7848

he 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.