John Crane Type 2100 Unitized Elastomer Bellows Seal

Overview

John Crane Type 2100 is a compact, fully unitized, single spring elastomer bellows mechanical seal designed for centrifugal, rotary and turbine pumps, compressors, chillers, blenders and other rotary equipment. Because the face assembly, the seat and the drive are supplied as one unit, a maintenance technician can fit or replace the seal quickly without setting working lengths on the shaft, and the pressure supported bellows resists creasing and folding when system pressure rises. John Crane positions the John Crane Type 2100 for water-based applications such as wastewater treatment, potable water, HVAC, pool and spa duties, pulp and paper, food processing, marine and other general services.

Seven Star LLC supplies the John Crane Type 2100 to customers in Oman and the GCC, with engineering support in Muscat. Water, cooling and utility pumps are found in every power station, desalination plant, hotel complex and industrial estate in the region, and a reliable unitized seal reduces both the cost of repairs and the time a pump is out of service. Our team can help you confirm the shaft size, seat arrangement and materials before you order.

Operating Principle

The John Crane Type 2100 seals the shaft with a pair of precisely lapped faces. The primary ring, normally resin-impregnated carbon graphite or sintered silicon carbide, rotates with the shaft and is pressed against a stationary seat, often aluminium oxide ceramic or sintered silicon carbide, by a single stainless steel spring and by hydraulic pressure of the pumped liquid. A thin fluid film between the faces provides lubrication and keeps leakage very low. The elastomer bellows seals the gap between the shaft and the primary ring and absorbs small movements, so the faces stay closed as the shaft end play or run-out changes.

Torque is transmitted from the shaft to the face through stainless steel drive bands that engage interlocking tangs. This positive key drive protects the bellows from torsional strain and prevents slipping during upset conditions. A non-clogging single coil spring keeps the faces closed during all phases of operation. The John Crane Type 2100 has a published pressure limit of 20 bar g (290 psig) and a speed of up to 5000 rpm depending on size, while remaining compact in working length.

Engineering Design of the John Crane Type 2100

The John Crane Type 2100 unitized assembly consists of a face or primary ring, a seat or mating ring, a drive band, a bellows and a spring. The design fits DIN 24960, ISO 3069 and ANSI B73.1 M-1991 dimensional standards, so it can replace many existing seals of similar envelope. Seal sizes range from 0.375 to 4.000 inches and from 10 to 100 mm. For a 25 mm shaft the published dimensions are an outside diameter D3 of 39 mm, a minimum bore D4 of 41 mm and a working length L3 of 20 mm. For a 50 mm shaft D3 is 66 mm, D4 is 70 mm and L3 is 30 mm, and for a 100 mm shaft D3 is 124 mm, D4 is 129 mm and L3 is 40 mm. In inch sizes a 1.000 inch seal has D3 of 1.535 inches and L3 of 0.787 inches.

The axial flexibility at working length is plus or minus 0.5 mm for seal sizes of 10 to 19 mm and plus or minus 1.0 mm for sizes of 20 to 100 mm, and equipment axial displacement must stay within these limits. Housing squareness to the shaft is also specified as a function of shaft speed. Material options for the John Crane Type 2100 are wide. The datasheet lists resin-impregnated carbon graphite and sintered silicon carbide faces, with antimony-loaded carbon graphite and tungsten carbide options, nitrile, ethylene propylene and fluorocarbon elastomers with HNBR and GFLT options, 316 stainless steel drive bands and springs, and aluminium oxide, sintered silicon carbide or John Crane Diamond seats.

Key Features of the John Crane Type 2100

The John Crane Type 2100 offers the following features according to the John Crane datasheet and product page.

• Unitized, easy-to-fit construction allows fast installation and replacement.
• The compact design fits DIN 24960, ISO 3069 and ANSI B73.1 M-1991 seal envelopes.
• A pressure supported bellows design prevents creasing or folding under high pressure.
• A non-clogging single coil spring keeps the faces closed and properly tracking in all phases of operation.
• Positive key drive via drive bands protects the bellows from torsional strain and will not slip during upset conditions.
• The widest array of material options includes high performance silicon carbides.
• The datasheet gives a pressure limit of 20 bar g (290 psig) and a speed of up to 5000 rpm depending on size.
• The temperature range is minus 40 to 150 degrees Celsius depending on materials in the current datasheet.

Industrial Applications

In the Sultanate of Oman the John Crane Type 2100 is a natural fit for water-based duties. Typical installations include chilled and condenser water pumps in district cooling and commercial HVAC plants, circulation pumps in desalination and potable water networks, wastewater and effluent transfer pumps, and general service pumps in industrial zones such as Sohar and Salalah. It is also applicable to pool and spa pumps in hospitality projects, marine pumps, food processing lines and chillers. Higher pressure or hydrocarbon duties should be reviewed with John Crane before this seal is selected.

The datasheet includes a worked method for deriving the pressure limit. The basic pressure rating applies to a clean, cool, lubricating liquid at 1800 rpm and is multiplied by factors for fluid lubricity, face materials and temperature. Examples include 0.60 for flashing hydrocarbons, 0.85 or 0.75 for silicon carbide against silicon carbide in standard or commercial duty, 0.60 for carbon against aluminium oxide ceramic, and 0.90 or 0.80 for carbon seals above 80 or 120 degrees Celsius. With the John Crane Type 2100, water and aqueous solutions use their own multiplier chart, so verify the combination for your pump with the manufacturer.

Technical Specifications

The table lists published data for the John Crane Type 2100 from the John Crane Type 2100 technical datasheet revised in February 2026.

Related Sealing and Pump Products

For a cartridge alternative, see the John Crane Type 5610 cartridge mechanical seal. For pumps in the same water duties as the John Crane Type 2100, review the Xylem Lowara intelligent pump range and the Bell and Gossett Series e-1531 centrifugal pump.

How to Order

To order the John Crane Type 2100, send an RFQ to Seven Star LLC with the shaft or sleeve diameter, the seat arrangement, the pumped fluid, the temperature, pressure and speed, and the pump make and model. We will confirm availability and lead time, provide the John Crane datasheet and arrange delivery to Muscat, Sohar, Salalah and other GCC locations. Our engineering team can also advise on replacement faces and elastomers for planned shutdown work.