Vulcan Mechanical
Seal Spare Parts Supplier
Type 12 · Type 18 · Type 20 · Type 24 · Type 75 · Type 1724 and 1724L
What a Vulcan type number actually names
Vulcan Seals, the Sheffield seal maker founded in 1986, numbers its seals by type, and every type on this page is a complete seal supplied with a named stationary: one of the same number on Type 12, 18, 20, 24 and 75, the Type 24 on Type 1724 and a Type 24.DINL on Type 1724L. Vulcan also sells stationaries as separate products, some under the same number as a seal, so reading a number as either the whole seal or the seat alone without checking is where a Vulcan line goes wrong first. VULKAN, spelt with a K, is a different company that makes flexible couplings; a coupling element on a requisition belongs on the VULKAN coupling page, not here.
Type 12
A robust O-ring mounted pusher seal with a narrow monolithic stainless steel head, driven by a conical spring that grips the shaft. Conical spring seals turn one way only, and Vulcan gives the clockwise and anti-clockwise builds different part codes, so the direction of rotation is part of the order. The complete seal comes with a Type 12 stationary to suit pre-DIN Italian housing sizes; say whether the head, the stationary or both are wanted.
Type 18
An axially compact elastomer bellows seal for water pumps, flexible enough to take up misalignment and shaft run-out. The bellows grips the shaft under the coil end and drives the seal in either direction of rotation. It comes with a Type 18 boot-mounted stationary and is designed for very short seal chambers with a wide radial clearance, so the chamber is what to check, not the direction.
Type 20
A rubber diaphragm mounted parallel spring seal with a self-adjusting head that takes up minor misalignment and run-out, working in both directions of rotation. It comes with a Type 20 boot-mounted stationary for common metric and imperial UK and European regular-length seal chambers; Vulcan describes Type 24 in the same terms, and the stationary and the chamber it suits are what separate the two.
Type 24
A rubber diaphragm mounted parallel spring seal with a self-adjusting head, supplied with a Type 24 boot-mounted stationary that makes it compatible with DIN 24960 / EN 12756 L1K chamber dimensions. Vulcan also sells Type 24 DIN O-ring seats on their own, in a short form and a long form with anti-rotation provision, so a line that reads only Type 24 may mean the seat: say which.
Type 75
A compact, stationary-mounted elastomer bellows seal for high shaft-speed water pumps on low-pressure light water circulation duty. The sprung unit is pressed into the pump housing and a boot-mounted rotary counter ring sits in a recess in the impeller, so nothing touches the shaft, it runs in either direction, and one size can serve several shaft sizes. It comes with a Type 75 boot-mounted stationary for US-design housings, which is why the pump make and model matter more here than the shaft size.
Type 1724 · Type 1724L
A radially compact elastomer bellows non-pusher seal with a retained, positively driven face and a non-clogging, self-aligning spring; the bellows grips the shaft, so it runs in either direction. Type 1724 comes with the Type 24 boot-mounted stationary and Type 1724L with a Type 24.DINL O-ring mounted stationary with anti-rotation provision, both to DIN 24960 / EN 12756 L1K chamber dimensions. The letter decides which stationary is quoted.
A Vulcan type number names a seal; its stationary decides the chamber
The same kind of rotary head can sit in different chambers depending on the stationary supplied with it, and that is not obvious from the number alone.
Type 20 and Type 24 are described by Vulcan in the same terms, a rubber diaphragm mounted parallel spring seal with a self-adjusting head, and differ in the boot-mounted stationary supplied with each: Type 20 for common UK and European regular-length chambers, Type 24 for DIN 24960 / EN 12756 L1K chambers. Type 1724 and Type 1724L differ in the stationary alone, a boot-mounted Type 24 on one and an O-ring mounted Type 24.DINL with anti-rotation provision on the other. Type 12 suits pre-DIN Italian housings, Type 18 very short chambers with a wide radial clearance, and Type 75 US-design housings.
Direction of rotation decides the order on one type here. Type 12 is a conical spring seal, and Vulcan's conical spring seals turn one way only, with different part codes for clockwise and anti-clockwise operation. Type 18, Type 1724 and Type 1724L are driven by an elastomer bellows, Type 20 and Type 24 by a rubber diaphragm, and Type 75 does not touch the shaft at all; Vulcan describes all of these as bi-directional. Vulcan also mixes rotary and stationary types to suit a housing, so the stationary in the pump may not be the standard one — read it from the seal as removed.
What a Vulcan line resolves to
Grouped as the six designations divide, because a Type 12 line and a Type 1724 line are not asking for the same kind of part.
- Stationaries ordered on their own, including Type 12 stationaries and Type 24 DIN O-ring seats in short and long forms
- Rotary heads, including the narrow monolithic stainless steel head of Type 12, quoted for the direction of rotation
- Elastomer bellows assemblies and boot-mounted stationaries for Type 18 short seal chambers
- Rubber diaphragm mounted parallel spring assemblies and self-adjusting heads for Type 20 and Type 24
- Boot-mounted stationaries for Type 20, Type 24 and Type 75, matched to the chamber standard
- Elastomer bellows units for Type 1724 and Type 1724L, with the Type 24 or Type 24.DINL stationary that goes with each
- Non-clogging springs and positively driven drive members on the bellows types
- O-rings and other elastomer seals, quoted by compound rather than by size alone
- Carbon and stainless face and seat materials matched to the part removed
- Complete rotary-and-stationary assemblies where the pair is ordered together
- Repair kits, quoted against the assembly rather than as loose items
A line that reads only a type number may mean the complete seal or a stationary sold on its own — say which one is wanted before the rest of the kit is quoted. Broader consumable routing sits on marine seals, gaskets and bearings.
The fields a Vulcan requisition tends to be missing
Written as an audit of the lines that come back for a second question rather than as a general checklist.
- The full type designation as marked, including any L suffix
- Whether the line is the complete seal or the stationary alone, and which stationary is fitted (for example a Type 24 boot-mounted or a Type 24.DINL O-ring mounted seat)
- On a Type 12, the direction of rotation: clockwise and anti-clockwise builds carry different part codes
- Photographs of the removed seal from the face side and the drive side
- Whether a stationary was supplied with the seal, or is being ordered separately
- The pump make, model, serial number and the system the pump serves
- The shaft or sleeve diameter measured at the seal
- The medium in plain words, and whether it carries solids or has been heated
- Whether the seal has run dry, or the pump been started against a shut valve
- Any American-style code already held: Vulcan accepts the common PS codes with VS in place of PS, and converts descriptive codes such as C-1 into a Vulcan rotary and stationary pair
- Whether the machine is single-sealed or double-sealed, and which one this concerns
- Vessel and IMO number, the port and the ETA
Tools for this equipment: the mechanical seal material code for the face, seat, secondary seal and spring letters, and the O-ring size finder for the secondary O-rings. For a seal built to EN 12756 dimensions, the mechanical seal size finder works from the shaft diameter or the measured installation length.
What is being replaced decides the route, not just what it is called
A Vulcan line splits along what is actually being renewed, and that is not always the whole seal.
Where a line is a stationary alone, the question is whether it matches the rotary head and the chamber already in service, not whether the whole seal is being renewed. Where a complete seal is being ordered, the stationary supplied with it decides whether a quoted alternative fits the chamber — regular-length UK and European chambers for Type 20, EN 12756 L1K for Type 24, Type 1724 and Type 1724L, US-design housings for Type 75 — and on a Type 12 the direction of rotation decides it as well.
On route: O-rings, elastomer diaphragms and bellows units, and other elastomer parts by compound are ordinary size-and-material questions, and a verified alternative can be reviewed on them. Complete rotary heads, stationaries matched to a head already in service, and any line known only by a Vulcan part code go to an OEM-route review. Vessel Core marks the proposed route against each line.
Vulcan seals — questions buyers ask
My old seal is stamped Type 12. Is that the whole seal to order?
Yes, Type 12 is a complete seal: an O-ring mounted conical spring seal supplied with a Type 12 stationary to suit pre-DIN Italian housing sizes. Say whether the head, the stationary or both are being changed, and give the direction of rotation, because Type 12 has separate part codes for clockwise and anti-clockwise shafts.
Why does direction of rotation matter on some of these types and not others?
Because of how each type is driven. Type 12 is driven by a conical spring gripping the shaft, and Vulcan builds its conical spring seals for one direction only, with separate clockwise and anti-clockwise part codes. Type 18, Type 1724 and Type 1724L are driven by an elastomer bellows, Type 20 and Type 24 by a rubber diaphragm, and Type 75 does not touch the shaft; Vulcan describes all of these as bi-directional.
Is Type 75 a physical part I can order by that number alone?
It is a complete seal, but the number alone is not enough. Type 75 is a compact elastomer bellows seal for high shaft-speed water pumps: the sprung unit is pressed into the pump housing, a boot-mounted rotary counter ring sits in a recess in the impeller, and a Type 75 stationary suits US-design housings. Because nothing touches the shaft, one size can serve several shaft sizes, so send the pump make and model and a photograph of the seal as removed, not the shaft size alone.
What comes with a Type 24 or a Type 1724?
Both arrive with a stationary. Type 24 is a rubber diaphragm mounted parallel spring seal supplied with a Type 24 boot-mounted stationary, which makes it compatible with DIN 24960 / EN 12756 L1K chamber dimensions. Type 1724 is a radially compact elastomer bellows seal supplied with the same Type 24 boot-mounted stationary; Type 1724L comes instead with a Type 24.DINL O-ring mounted stationary with anti-rotation provision, so the letter belongs in the request.
Is Vessel Core connected to Vulcan?
No, and there is no agreement of any kind. Vessel Core holds no dealership, distribution, representation or partnership agreement with Vulcan, and quoting a component against one of its type designations implies no approval by the maker and no claim of interchangeability.
Submit your RFQ now.
Send your Vulcan request — the type code from the seal (Type 12, 18, 20, 24, 75, 1724 or 1724L), the shaft size measured, and the direction of rotation where it applies. A photograph of the seal as removed is what settles it, not the pump nameplate alone.
