8B1/8B1T

TYPE 8B1/8B1T
Elastomer O-Ring Seals

A – Face/Primary Ring
B – Seat/Mating Ring
C – Spring
D – O-Ring
E – Disc
F – Anti-X Ring H
G – Retainer C
E
H – Set Screws I
F
I – Snap Ring
D

G
D

A
B

Product Description Performance Capabilities

Rugged Type 8B1/8B1T mechanical seals are available ■ Temperatures:
in a wide variety of elastomers for handling practically -40˚C to 260˚C/-40˚F to 500˚F
every industrial fluid. All components are held together (depending on materials used)
by a snap ring in a unitized construction design. ■ Pressures:
■ General industrial applications including refining, chemical Type 8B1: 76 bar g/1100 psig
processing, food and beverage, petrochemical processing, Type 8B1T: 21 bar g/300 psig
pharmaceutical, wastewater and power generation. For hydrostatic pressure limits, refer to the
■ Seals can be repaired easily on-site or at any John Crane Hydrostatic Pressure Limits chart.
Service Center. ■ Speeds:
■ Seals can be shaft mounted or built into a cartridge as Up to 25 m/s / 5000 fpm
illustrated above. NOTE: For applications with speeds greater than
25 m/s/ 5000 fpm, a rotating seat (RS)
Design Features arrangement is recommended.
■ Positive Set Screen Mechanical Drive Design —
reduces slippage on shaft and sleeve to eliminate
galling and premature wear.
■ Lapped Faces — lapping process results in high
precision finish for optimal sealing performance.
■ Compact Design — permits use in all types of rotating
equipment--centrifugal pumps, mixers and agitators.
■ Balanced Design — balanced construction, including
anti-extrusion ring, permits use in higher pressures.
■ O-Ring Design — permits accommodation of many
different fluids through use of wide variety of materials.
■ Full (8B1) and narrow (8B1T) cross-section designs.
 TYPE 8B1/8B1T
8B1/8B1T
Elastomer O-Ring Seals

Type 8B1 Typical Arrangement/Dimensional Data

D11 Pin L45 Pin Ext.

(N) number of pins (D12) pin diameter Pin press

fit into collar or impeller. Engages holes in retainer.
Design option standard on Type 8B1 Seals only.

16-32µ" 0.040"
MIN.
D4
D3 L9 L65
MIN.
SEAL OD
D2 BORE
L3 D1
± 0.002" ±0.031" W. H. ± 0.002" 20˚
For ease of installation, the lead-in
edge of shaft or sleeve should be
chamfered as shown.

Type 8B1 Dimensional Data (inches)

Seal Working Height
Size D1 D2 D3 D4 D11 D12 L3 L9 L45 L65 N
1.000 0.875 1.000 1.562 1.750 .--- .--- 1.312 .187 .--- .343 .---
1.125 1.000 1.125 1.687 1.875 1.437 .187 1.375 .218 .187 .343 1
1.250 1.125 1.250 1.875 2.000 1.562 .187 1.375 .187 .187 .343 1
1.375 1.125 1.375 2.000 2.125 1.687 .187 1.437 .187 .187 .343 1
1.500 1.250 1.500 2.125 2.250 1.812 .187 1.437 .187 .187 .343 1
1.625 1.375 1.625 2.375 2.500 2.000 .187 1.750 .281 .250 .437 1
1.750 1.500 1.750 2.500 2.625 2.125 .187 1.750 .281 .250 .437 1
1.875 1.625 1.875 2.625 2.750 2.250 .187 1.750 .281 .250 .437 1
2.000 1.750 2.000 2.750 2.875 2.375 .187 1.750 .281 .250 .437 1
2.125 1.875 2.125 3.000 3.125 2.593 .250 2.062 .343 .312 .500 1
2.250 2.000 2.250 3.125 3.250 2.718 .250 2.062 .343 .312 .500 1
2.375 2.125 2.375 3.250 3.375 2.843 .250 2.062 .343 .312 .500 1
2.500 2.250 2.500 3.375 3.500 2.968 .250 2.062 .343 .312 .500 1
2.625 2.375 2.625 3.500 3.625 3.062 .312 2.062 .343 .312 .500 1
2.750 2.500 2.750 3.625 3.750 3.187 .312 2.062 .343 .312 .500 1
2.875 2.625 2.875 3.750 3.875 3.312 .312 2.062 .343 .312 .500 1
3.000 2.750 3.000 3.812 4.000 3.406 .312 2.062 .343 .312 .500 2
3.125 2.875 3.125 3.937 4.062 3.531 .312 2.062 .343 .312 .562 1
3.250 3.000 3.250 4.125 4.250 3.687 .312 2.062 .343 .312 .562 1
3.375 3.125 3.375 4.250 4.375 3.812 .312 2.062 .343 .312 .562 1
3.500 3.250 3.500 4.375 4.500 3.937 .312 2.062 .343 .312 .562 1
3.625 3.375 3.625 4.500 4.625 4.062 .312 2.062 .343 .312 .562 1
3.750 3.500 3.750 4.625 4.750 4.187 .312 2.062 .343 .312 .562 1
3.875 3.625 3.875 4.750 4.875 4.312 .312 2.062 .343 .312 .562 1
4.000 3.750 4.000 4.875 5.000 4.437 .312 2.062 .343 .312 .562 2
4.125 3.875 4.125 5.000 5.125 4.656 .312 2.062 .343 .312 .562 2
4.250 4.000 4.250 5.250 5.375 4.781 .312 2.062 .343 .312 .562 2
4.375 4.125 4.375 5.375 5.500 4.906 .312 2.062 .343 .312 .562 2
4.500 4.250 4.500 5.500 5.625 4.968 .312 2.062 .343 .312 .562 2
4.625 4.375 4.625 5.625 5.750 .--- .--- 2.062 .343 .312 .562 --
4.750 4.500 4.750 5.750 5.875 5.250 .312 2.062 .343 .312 .562 2
4.875 4.625 4.875 5.875 6.000 5.375 .312 2.062 .343 .312 .562 2
5.000 4.750 5.000 6.000 6.125 5.500 .312 2.062 .343 .312 .562 2
5.125 4.875 5.125 6.125 6.250 5.625 .312 2.062 .343 .312 .562 2
5.250 5.000 5.250 6.500 6.625 5.750 .312 2.375 .312 .312 .625 2
5.375 5.125 5.375 6.625 6.750 5.875 .312 2.375 .312 .312 .625 2
5.500 5.250 5.500 6.750 6.875 6.000 .312 2.375 .312 .312 .625 2
5.625 5.375 5.625 6.875 7.000 6.125 .312 2.375 .312 .312 .625 2
5.750 5.500 5.750 7.000 7.125 6.250 .312 2.375 .390 .437 .625 2
5.875 5.625 5.875 7.125 7.250 5.375 .281 2.375 .390 .437 .625 2
6.000 5.750 6.000 7.250 7.375 6.500 .281 2.375 .312 .437 .625 2
 TYPE 8B1/8B1T
Elastomer O-Ring Seals

Type 8B1T Typical Arrangement/Dimensional Data

D11 Pin L45 Pin Ext.

(N) number of pins (D12) pin diameter Pin press

fit into collar or impeller. Engages holes in retainer.
Design option standard on Type 8B1 Seals only.

16-32µ" 0.040"
MIN.
D4
D3 L9 L65
MIN.
SEAL OD
D2 BORE
L3 D1
± 0.002" ±0.031" W. H. ± 0.002" 20˚
For ease of installation, the lead-in
edge of shaft or sleeve should be
chamfered as shown.

Type 8B1T Dimensional Data (inches)

Seal Working Height
Size D1 D2 D3 D4 L3 L9 L65
1.000 0.875 1.000 1.437 1.625 1.312 .187 .343
1.125 1.000 1.125 1.562 1.750 1.375 .218 .343
1.250 1.125 1.250 1.687 1.875 1.375 .187 .343
1.375 1.125 1.375 1.937 2.125 1.687 .187 .343
1.500 1.250 1.500 1.937 2.125 1.437 .187 .343
1.625 1.375 1.625 2.250 2.437 1.593 .187 .437
1.750 1.500 1.750 2.312 2.500 1.750 .281 .437
1.875 1.625 1.875 2.500 2.687 1.750 .281 .437
2.000 1.750 2.000 2.625 2.812 1.750 .281 .437
2.125 1.875 2.125 2.812 3.000 2.062 .343 .500
2.250 2.000 2.250 2.843 3.031 1.750 .234 .500
2.375 2.125 2.375 3.000 3.187 2.062 .343 .500
2.500 2.250 2.500 3.125 3.312 1.750 .234 .500
2.625 2.375 2.625 3.250 3.437 2.062 .343 .500
2.750 2.500 2.750 3.375 3.562 2.062 .343 .500
2.875 2.625 2.875 3.500 3.687 2.062 .343 .500
3.000 2.750 3.000 3.625 3.812 2.062 .343 .500
3.125 2.875 3.125 3.750 3.937 2.062 .343 .562
3.250 3.000 3.250 3.875 4.062 2.062 .343 .562
3.375 3.125 3.375 4.000 4.187 2.062 .343 .562
3.500 3.250 3.500 4.125 4.312 2.062 .343 .562
3.625 3.375 3.625 4.250 4.437 2.062 .343 .562
3.750 3.500 3.750 4.375 4.562 2.062 .343 .562
3.875 3.625 3.875 4.500 4.687 2.062 .343 .562
4.000 3.750 4.000 4.625 4.812 2.062 .343 .562
 TYPE 8B1/8B1T
Elastomer O-Ring Seals

Basic Pressure Ratings

Pressure (psig) Pressure (bar g)
1200 83 To determine the maximum
pressure for a Type 8B1 or 8B1T,
1000 multiply the maximum pressure
69
Type 8B1 Carbon vs. by the Multiplier Factors to
Silicon Carbide (3600 rpm) obtain the maximum operating
800 Note: Type 8B1RS required for seal sizes 55 pressure.
above 5.125'' at 3600 rpm as speed exceeds
25 m/s/5000 fpm For hard combinations consult
600 John Crane Engineering.
41.3

400 27.6

200 Type 8B1T Carbon vs. 13.8

Silicon Carbide (3600 rpm)
0 0
0 1 2 3 4 5 6 7 (inches)

0 25 51 76 102 127 152 178 (mm)

Seal Size

The Basic Pressure Rating is for a standard Type 8B1 or 8B1T seal, as shown in the typical arrangement, when installed according
to the criteria given in this data sheet and generally accepted industrial practices.

The Basic Pressure Rating assumes stable operation at 3600 rpm in a clean, cool, lubricating, nonvolatile liquid, with an adequate
flush rate. When used with the Multiplier Factors, the Basic Pressure Rating can be adjusted to provide a conservative estimate
of the dynamic pressure rating. For process services outside this range or a more precise assessment of the dynamic pressure
rating, contact John Crane for more information.

Multiplier Factors
Example for Determining Pressure Rating Limits
Multiplier
Selection Considerations Factor Seal: 50mm/2" diameter Type 8B1
Product: Water
Speed 3600 rpm x 1.00
Face Material: Carbon vs. Silicon Carbide
Above 3600 rpm* **
Temperature: 16°C/60°F
Sealed Fluid Petrol/Gasoline, Kerosene, or better x 1.00 Speed: 1800 rpm
Lubricity Water and Aqueous Solutions x 0.75 Using the Basic Pressure Rating chart, the
Flashing Hydrocarbons*** x 0.60 maximum pressure would be 76 bar g/1100 psig.
(Specific Gravity ≤.65)
From the Multiplier Factors chart, apply the
multipliers for the specific service requirements to
Sealed Fluid Below 80°C/175°F x 1.00
determine the maximum operating pressure for
Temperature From 80°C to 125°C/175°F to 250°F x 0.90
the application.
(for carbon From 125°C to 180°C/250°F to 350°F x 0.80
only) Above 180°C/350°F x 0.65 76 bar g/1100 psig x 1.00 x 0.75 x 1.00 =
825 psig/57 bar g.
* Not to exceed 25m/s/5000 fpm. At 3600 rpm with the service conditions noted,
a 50mm/2" diameter Type 8B1 Seal has a
** Multiplier = 3600/new speed
Example: If new speed = 4000 rpm maximum operating limit of 825 psig/57 bar g.
Multiplier = 3600/4000 = 0.90 If operating pressure exceeds the pressure limit,
consult John Crane.
*** The ratio of sealed pressure to vapor pressure must be greater than 1.5,
otherwise consult John Crane. If the specific gravity is less than 0.60,
consult John Crane.
 TYPE 8B1/8B1T
Elastomer O-Ring Seals

Hydrostatic Pressure Limits

Pressure (psig) Pressure (bar g)
3000 207

2500 172

2000 138
Type 8B1 Carbon
1500 103

1000 69

500 35
CUT LINE FOR SHORT PAGE

0 0
0 1 2 3 4 5 6 (inches)

0 25 51 76 102 127 152 (mm)

Seal Size

Elastomer Temperature Limits

Compound Temperature
(°C) –70 –20 40 100 150 200 250

Nitrile -40˚C to 120˚C / -40˚F to 250˚F

Fluorocarbon -29˚C to 205˚C / -20˚F to 400˚F

Ethylene Propylene -40˚C to 149˚C / -40˚F to 300˚F

Neoprene® -40˚C to 100˚C / -40˚F to 212˚F

Perfluoroelastomer -25˚C to 260˚C / -13˚F to 500˚F

Aflas® -30˚C to 205˚C / -20˚F to 400˚F

(°F) –100 0 100 200 300 400 500

Criteria for Installation

Shaft/Sleeve Limits

Surface Finish (max.) 0.8µm/32 Ra

Ovality/Out of Roundness (Shaft) 0.051mm/0.002"

End Play/Axial Float Allowance ±0.13mm/0.005"

 TYPE 8B1/8B1T
Elastomer O-Ring Seals

Materials of Construction

SEAL COMPONENTS MATERIALS

Description Standard Options

Face/Primary Ring Carbon Carbon (Nuclear Service)
Carbon Severe (Chemical Service)
Nickel Binder Tungsten Carbide
Silicon Carbide

O-Ring Fluorocarbon Aflas®

Ethylene Propylene
Neoprene®
Nitrile
Perfluoroelastomer

Disc 316 Stainless Steel Alloy 400 (Monel®)

Set Screws Alloy 20 Cb-3
Retainer Hastelloy B®
Snap Ring Alloy C-276
Springs Titanium

Aflas is a registered trademark of Asashi Glass Co. Ltd.

Hastelloy B is a registered trademark of Haynes Internation, Inc.
Monel is a registered trademark of Inco Alloys International, Inc.
Neoprene is a registered trademark of DuPont Dow.

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Slough, UK São Paulo, Brazil Dubai, United Arab Emirates Morton Grove, Illinois USA
Tel: 44-1753-224000 Tel: 55-11-3371-2500 Tel: 971-4-3438940 1-800-SEALING
Fax: 44-1753-224224 Fax: 55-11-3371-2599 Fax: 971-4-3438970 Tel: 1-847-967-2400
Fax: 1-847-967-3915
For your nearest John Crane facility, please contact one of the locations above.
If the products featured will be used in a potentially dangerous and/or hazardous process, your John Crane representative should be consulted prior to their selection and use.
In the interest of continuous development, John Crane Companies reserve the right to alter designs and specifications without prior notice. It is dangerous to smoke while handling
products made from PTFE. Old and new PTFE products must not be incinerated.

©2004 John Crane Inc. Print 7/04 www.johncrane.com ISO 9001, ISO 14001, ISO/TS 16949 Certified. S-8B1/8B1T