The John Crane Type 21 is the most widely used OEM rubber-bellows single mechanical seal — clean water, wastewater, HVAC and general pumps. If the OEM won't sell you one piece, or the lead time is 8–16 weeks, we source a size-and-function equivalent through our coordination, delivered in 4–6 weeks.
Typical Type 21 dimensions and duty. Your exact shaft size and elastomer drive the equivalent we source — confirm with the supplying factory.
| Parameter | Typical range / note |
|---|---|
| Seal type | Single, unbalanced, rubber-bellows (elastomer bellows) mechanical seal |
| Standard | DIN 24960 / EN 12756 / ISO 3069 / GB 6556 (installation dimensions standardised) |
| Shaft diameter | 0.5"–3" (12.7–76.2 mm) common; some arrangements to 4" (100 mm) |
| Pressure | Up to ~10–15 bar (elastomer dependent) |
| Temperature | −40 to +200 °C (elastomer dependent) |
| Speed | Up to ~10–18 m/s |
| Elastomer | NBR / FKM / EPDM (confirm media & temperature) |
The Type 21 is one of the most cross-referenced seals in the industry. Listed equivalents are matched by size and function; they are not OEM parts. We coordinate Type 21-family equivalents from ISO 9001-certified partner plants through our coordination.
| OEM / brand | Equivalent model code |
|---|---|
| Burgmann / EagleBurgmann | MG1, MG12, MG13 (MG13 ≈ the compact Type 21) |
| Flowserve / Pac-Seal | Pac-Seal 21, 110, 192 |
| AESSEAL | P04, P04T |
| Vulcan | Type 11 |
| Roten / Sterling / US Seal | Roten 21A / Sterling 212A / US Seal C |
Common plant model codes for this family include FT21-type (John Crane Type 21 type) and Burgmann MG1-type equivalents. The exact equivalent code, face-material combination and MOQ are confirmed per inquiry — we prioritise plants that accept 1–2 pieces (some volume plants require 5+, which we flag during quoting).
The John Crane Type 21 is a rubber-bellows single mechanical seal. Industry-standard equivalents include Burgmann MG1/MG12/MG13, Flowserve Pac-Seal 21/110/192, AESSEAL P04/P04T and Vulcan Type 11. We source a size-and-function equivalent through our coordination from ISO 9001-certified partner plants; confirm the exact code, face material and MOQ per inquiry.
We are a sourcing coordinator, not a distributor. We do not claim standing stock on every item. Availability and lead time are confirmed per inquiry — typically 4–6 weeks versus the OEM's 8–16 weeks.
Yes. Small-batch and long-tail orders (1–2 pieces) are exactly the segment we serve. We prioritise partner plants that accept 1–2 pieces; some volume plants require 5+, which we flag during quoting.
Send the OEM model (John Crane Type 21) and your shaft size / pump model via the contact form. No part number? Send a photo + 4 dimensions and we match it remotely.
Send your shaft size + pump model — we return the equivalent and a quote in 1–2 days.