2100 Rubber Bellow Mechanical Seal

For industrial process pumps, mid-pressure chemical transfer skids, and refinery utility service where a single-spring rubber bellow design still makes commercial sense but the pump runs harder than catalogue conditions, the 2100 Rubber Bellow Mechanical Seal is the upgrade path. Buy direct from the Qixing factory in China — same-day quotation, factory pricing, OEM and wholesale supply worldwide.

Where the 2100 Sits in the Rubber Bellow Family

Mechanical seal selection becomes obvious once the duty point is plotted on a pressure-velocity map. The table below shows the rubber bellow mechanical seal family in zones — light-duty, general-purpose, industrial standard, industrial heavy, and severe-duty. The 2100 occupies the industrial-heavy zone:

Two reading notes. First, the zones overlap in real applications — a 1.5 MPa duty at 8 m/s could be run by an industrial-standard seal but is more conservatively specified at the industrial-heavy 2100. Second, the boundary between industrial-heavy and severe-duty is also the boundary between single-spring rubber bellow construction and multi-spring construction; above 1.8 MPa or 15 m/s, Qixing recommends moving up to the 891 multi-spring family rather than pushing a rubber bellow design past its design limits.

2100 Rubber Bellow Mechanical Seal Specifications

Dimensions Chart

All dimensions in millimetres. The 2100 is supplied in metric sizes 10 mm to 100 mm as standard catalogue inventory. Imperial fractional sizes from 3/8 inch to 4 inch are available on request — typical lead time 15 to 25 days for non-stocked sizes.

Common Failure Modes the 2100 Addresses

Four failure modes account for almost all premature failures of standard rubber bellow mechanical seals when they are pushed beyond their designed PV envelope. The 2100 is engineered around each:

Failure mode: Bellow extrusion under pressure

Root cause: elastomer bellows compressed against the shaft sleeve squeeze into the running gap and tear, causing immediate leakage. Common at pressures above 1.0 MPa with standard NBR or EPDM bellows.

How the 2100 addresses it: the 2100 bellow profile is reinforced at the high-stress shoulder, and FKM compound is offered as standard for pressures above 1.2 MPa. The bellow geometry distributes pressure load instead of concentrating it at the bond line.

Failure mode: Face overheating at high velocity

Root cause: carbon and ceramic faces generate frictional heat in proportion to PV product. Above 13 m/s shaft speed, standard face pairings exceed the heat dissipation capability of the seal chamber and the faces glaze or crack.

How the 2100 addresses it: the 2100 ships with SiC / SiC or TC / SiC face pairings as standard rather than Ceramic / Carbon. Silicon carbide and tungsten carbide dissipate heat roughly 5 to 10 times faster than ceramic, keeping the face interface within thermal tolerance up to the 15 m/s envelope.

Failure mode: Spring fatigue under cycling pressure

Root cause: stainless coil springs in standard rubber bellow seals are sized for ~10 million cycles at design pressure. Pumps running at 1.5 to 1.8 MPa with frequent start-stop cycles fatigue the spring before the faces wear out.

How the 2100 addresses it: the Qixing 2100 uses multiple springs (not a single helical spring) sized for the upper PV envelope, distributing load and extending fatigue life to typically 30 million cycles. SS316 and Hastelloy spring options are available for chloride and chemical service.

Failure mode: Drive collar slip on the shaft sleeve

Root cause: the rubber bellow itself drives the rotating face through interference fit on the sleeve. Under high torque (high pressure × shaft speed), the rubber slips on the sleeve, the face loses rotational drive, and the seal opens.

How the 2100 addresses it: the 2100 drive collar is mechanically retained against the sleeve with a positive-engagement key, not relying on rubber friction alone. Slip is eliminated regardless of operating conditions within the rated PV envelope.

Industries and Applications by Service Severity

Moderately demanding service

Industrial booster and transfer pumps in water treatment, light chemical service, food and beverage processing, pharmaceutical CIP loops, and HVAC plant rooms where standard rubber bellow seals are pushed close to their PV ceiling.

Demanding service

Refinery utility pumps (cooling water, sour water transfer), pulp and paper stock pumps, mining slurry transfer with TSS up to 1%, marine seawater cooling pumps, and chemical-resistant industrial transfer at moderate concentrations.

OEM pump-building service

Wholesale 2100 rubber bellow mechanical seal supply to OEM pump platforms where the design pump duty falls inside the 2100 PV zone and the buyer wants a private-label or unbranded supply contract at annual volume pricing.

How Qixing Builds the 2100 for the Upper PV Envelope

Three production decisions separate the Qixing 2100 from a generic rubber bellow mechanical seal at the same nominal dimensions. First, spring metallurgy is matched to operating conditions at order: SS304 for water and mild service, SS316 for chloride exposure, Hastelloy C for chemical service. Spring loads are verified per batch against the master gauge at the dimensional inspection step.

Second, face material is biased toward hard pairings as the default rather than the upgrade. Where general-purpose rubber bellow seals ship Ceramic / Carbon, the Qixing 2100 ships SiC / SiC or TC / SiC unless the buyer specifies the soft pairing — the harder defaults are what carries the seal through the upper PV envelope. Face flatness is lapped to ≤ 0.0009 mm and verified optically before assembly.

Third, every completed 2100 is dynamic-tested at 1.5 times rated pressure with water for two minutes before packing, with the test result recorded against the unit serial number. Certificate of Conformity, material certs and dimensional inspection reports are included with the shipment at no extra charge for OEM and qualification orders.

Buy the Qixing 2100 Direct

Send Qixing the pump duty point — pressure, shaft speed, media, shaft diameter, temperature — and the application engineering team confirms whether the 2100 rubber bellow mechanical seal is the correct PV-zone match before quotation. Stock sizes ship in 3 to 7 days; OEM custom configurations in 15 to 25 days. Same-day factory quotation, wholesale and OEM pricing, full traceability documentation. Contact Qixing to buy the 2100 direct from the factory in China.