Five letters, five parts
Seal face, stationary seat, secondary seals, spring and other parts, in that order. A double seal adds letters for the atmosphere side.
Reference tool — not a selection
Read the seal code before it goes in an RFQ.
Mechanical seal
Five letters, five parts.
Type the material code. Below the examples, the code of an offered seal can be checked against it, position by position. The section and the RFQ line update with every change.
Examples:
Replacement check
On the material codes alone: the seal type, the size and the operating conditions decide.
All 130 engineering tools
A mechanical seal’s materials are written as five letters to EN 12756 (formerly DIN 24960): seal face, stationary seat, secondary seals, spring, other parts; a double seal adds letters for the atmosphere side. Type the code from the seal or its box, and the reader takes it apart position by position, shows the parts in section and writes the RFQ line.
The letters are standard; the digits after them are set differently by each maker, and the reader decodes only letters that two sources read the same way. The seal and pump datasheets still decide.
How a code is read
Position, letter, digit.
The position decides
V is aluminium oxide on a face but FKM in an O-ring; E is chromium steel or EPDM; S is cast CrMo steel or silicone rubber.
Digits are the maker’s
Q1, U2 or V1 name a grade inside a group, and makers number them differently. The letter is the standard; the digit is the catalogue.
| Letter | Face and seat (1, 2) | Secondary seals (3) | Spring (4) | Other parts (5) |
|---|---|---|---|---|
| A | carbon graphite, antimony-impregnated | — | — | — |
| B | carbon graphite, resin-impregnated | — | — | — |
| E | chromium steel | EPDM | — | chromium steel |
| F | — | — | CrNi steel | CrNi steel |
| G | CrNiMo steel | — | CrNiMo steel | CrNiMo steel |
| K | — | perfluoroelastomer (FFKM) | — | — |
| M | Hastelloy (nickel alloy) | elastomer with a PTFE or FEP cover | nickel alloy such as Hastelloy | nickel alloy such as Hastelloy |
| N | — | chloroprene rubber (CR) | — | — |
| P | — | nitrile rubber (NBR) | — | — |
| Q | silicon carbide | — | — | — |
| S | cast chromium-molybdenum steel | silicone rubber (VMQ) | — | — |
| T | — | — | — | other material |
| U | tungsten carbide | — | — | — |
| V | aluminium oxide (ceramic) | fluorocarbon rubber (FKM) | — | — |
| Y | reinforced PTFE | — | — | — |
Only letters both sources read the same way. For Y and T the digits agree too: Y1 glass-fibre and Y2 carbon reinforced PTFE; T1 steel 1.4505, T2 titanium, T3 Inconel 625, T4 Carpenter 42, T5 Incoloy 800.
Sources
Material key: EagleBurgmann, "Lexicon of Mechanical Seals" — the material code article and the overview tables for seal faces and seats, secondary seals, springs and construction parts (letters to DIN 24960, indices to Burgmann) — and F&T Dichtungstechnik, "Standardwerkstoffe — Werkstoff-Schlüssel nach EN 12756". Only letters with the same meaning in both are decoded. Digits: Burgmann’s tables and KSB’s seal code key use Q1 for pressureless-sintered silicon carbide, F&T for reaction-bonded; Y1, Y2 and T1 to T5, which agree, are decoded.
Before you send the seal
Questions about mechanical seals in an RFQ
What does BQ1EGG mean?
A material code to EN 12756, one letter per part: B, a resin-impregnated carbon graphite seal face; Q1, a silicon carbide seat, the 1 being the maker’s grade; E, EPDM secondary seals; G, a CrNiMo steel spring; G, CrNiMo steel for the other parts.
Why does V mean two different things?
Each position has its own list. On a seal face or seat V is aluminium oxide; in the secondary seals it is FKM. E, S and M change meaning in the same way, so a code is read position by position.
What do the digits after a letter mean?
A grade within the material group, set by the seal maker. Q1 is pressureless-sintered silicon carbide in one maker’s key and reaction-bonded in another’s, so quote the code as printed and, where it matters, name the grade.
What should the request include?
The seal designation as printed (type, size and material code), the shaft diameter, the pump maker, model and serial number, and the liquid and its temperature. A photograph of the old seal and its box label helps match it.
Code read?
Send the line with the photographs.
A decoded code is a cross-check, not proof. Attach photographs of the seal and its label, and Vessel Core checks them against the pump data before an offer goes back.
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