Serum Vial Seals
A serum vial seal is the aluminium closure crimped over the rubber stopper of a crimp-top serum vial, the standard multi-dose injection vial. Autofits makes serum vial seals in 13, 20, 28, 32 and 34 mm to match the neck finishes defined in ISO 8362-1, in three families: FlipTop® Optima flip-off, all-aluminium tear-off, and tear-down. Maximum opening force runs from 30 N at 13 mm to 65 N at 32 mm, and every seal is produced under ISO 15378:2017 with 100% high-speed camera inspection.
This page covers what a serum vial seal is, the sizes and dimensions across all three families, materials, forms of supply and how to order.
Key takeaways
- A serum vial is a crimp-top injection vial closed with a rubber stopper and an aluminium seal; the seal size is the neck finish, not the fill volume.
- Autofits supplies serum vial seals in 13, 20, 28, 32 and 34 mm. There is no 30 mm size.
- Three closure families fit a serum vial: FlipTop® Optima flip-off (13 to 34 mm), all-aluminium tear-off (13, 20, 32 mm) and tear-down (13, 20, 32 mm).
- Neck finishes follow ISO 8362-1; aluminium-plastic combination seals follow ISO 8362-6 and all-aluminium seals relate to ISO 8362-3.
- Maximum opening force is 30 N at 13 mm, 35 N at 20 and 28 mm, 65 N at 32 mm, varying with the number of bridges.
- Standard packing runs from 15,000 seals per box at 13 mm to 1,400 at 32 mm, in a 420 × 270 × 320 mm shipper.
What is a serum vial seal?
A serum vial seal is the aluminium seal crimped over the stopper of a serum vial: a glass injection vial with a flanged crimp-top neck, filled with a liquid drug product and usually presented as a multi-dose container. The stopper makes the sterile barrier by compressing against the glass; the seal holds that compression for the shelf life of the product and gives the user a controlled, one-way way in.
The distinction that matters when specifying is serum vial versus lyophilisation vial. A serum vial is stoppered fully at fill and crimped straight away. A lyophilisation vial is stoppered only half-way so vapour can escape during freeze-drying, then seated and crimped after the cycle, which needs a two-leg stopper and a different sequence on the line; see lyophilised products. Both use the same seal families and neck finishes, so the seal itself is often identical.
Three components have to agree on size for the crimp to seat cleanly: the vial neck, the rubber stopper, and the seal. Glass vial neck dimensions are set by ISO 8362-1 and the seal is built to match. Working back from a drug product instead, how to choose a vial cap size takes the same decision from the other end.
Sizes and the closure families that fit
Which families are available depends on the size.
| Size | FlipTop® Optima (flip-off) | Tear-off (all-aluminium) | Tear-Down (aluminium-plastic) | Size page |
|---|---|---|---|---|
| 13 mm | Yes | Yes | Yes | 13 mm seals |
| 20 mm | Yes | Yes | Yes | 20 mm seals |
| 28 mm | Yes | On request | On request | 28 mm seals |
| 32 mm | Yes | Yes | Yes | 32 mm seals |
| 34 mm | Yes | On request | On request | 34 mm seals |
The families differ in how the user gets in. The Optima flip-off leaves the aluminium crimped and lifts a polypropylene button to expose a small central injection point, the normal choice for a multi-dose serum vial entered several times. A tear-off seal is all metal, with the top torn away to expose the stopper. A tear-down seal opens by pulling and rotating the polypropylene disc anticlockwise so the whole seal lifts clear, and is used mainly for oral vaccination presentations.
Specifications and sizing
From the Autofits engineering drawings. Shipper box 420 × 270 × 320 mm. Values not carried on a drawing are shown as on request.
FlipTop® Optima flip-off, 13 to 34 mm
| Size | Inner Ø alu (D1) | Outer Ø disc (D2) | Total seal height | Alu thickness | Bridges | Max opening force | Standard packing per box |
|---|---|---|---|---|---|---|---|
| 13 mm | 13.36 min | 14.99 max | 7.62–8.38 | 0.16–0.20 | 6 taper | 30 N | 15,000 (5,000 × 3 bags) |
| 20 mm | 20.22 min | 23.14 max | 9.02–9.91 | 0.16–0.20 | 6 taper | 35 N | 6,000 (2,000 × 2 bags) |
| 28 mm | 27.60–28.20 | 30.10–31.10 | 11.06–12.06 | 0.17–0.23 | 8 | 35 N | 3,000 (1,500 × 2 bags) |
| 32 mm | 32.10–32.90 | 35.50–36.50 | 14.30–15.50 | 0.21–0.25 | 12 taper | 65 N | 1,400 (700 × 2 bags) |
| 34 mm | 33.60–34.00 | 35.50–36.50 | 15.00–16.00 | 0.20–0.25 | 8 taper | On request | On request |
All dimensions in millimetres. Optima top designs are Bridge, Button and Flower; the Button design carries intrinsic tamper evidence, a 12-stem flower moulded under the button disc.
Tear-off and Tear-Down
| Family and size | Inner Ø alu (D1) | Outer Ø disc or perforation (D2) | Total height | Alu thickness | Bridges or fins |
|---|---|---|---|---|---|
| Tear-off 13 mm | 13.20–13.60 | On request | 6.90–7.70 | On request | 2 |
| Tear-off 20 mm | 20.00–20.60 | 9.70–10.50 (perf) | 7.40–8.00 | 0.16–0.20 | 2 |
| Tear-off 32 mm | 32.40–32.60 | 17.80–18.20 (perf) | 13.00–13.60 | On request | On request |
| Tear-Down 13 mm | 13.30–13.50 | 14.80–15.40 (disc) | 6.80–8.30 | 0.18–0.22 | Bridge |
| Tear-Down 20 mm | 20.00–20.60 | 22.00–23.00 (disc) | 8.80–9.80 | On request | Bridge |
| Tear-Down 32 mm (flower) | 32.40–33.15 | 35.70–36.70 (disc) | 14.30–15.30 | 0.20–0.26 | 8 fins |
| Tear-down 20 mm, all-aluminium | 20.50–20.70 | 12.90–13.20 (perf) | 7.50–8.50 | 0.18–0.22 | 2 taper |
Materials and quality
The shell is AA8011 aluminium alloy to EN 15088:2005, supplied with EN 10204 3.1 certification and tested to BS EN 485-2:2008, REACH and RoHS compliant, with an epoxy lacquer coating to 21 CFR 175.300 which may be pigmented for colour. Polypropylene discs and buttons are moulded in-house on Japanese Toyo injection machines to IS 10910 and IS 10909, FDA 21 CFR 177.1520 and EC 1895/2005, with BADGE, NOGE and BFDGE not used. Heavy metals (chrome-VI, cadmium, mercury, lead) are held to a maximum 100 ppm total to EN 602 and EC 94/62, and components are BSE/TSE-free to EMEA/410/01 rev. 3.
Assembly is in an ISO Class 8 cleanroom in the 75,000 sq ft Nashik facility, with fully automated washing and 100% high-speed camera inspection. AQL is critical nil, major NMT 2.5%, minor NMT 4%, tailorable. Certification covers ISO 9001:2015, ISO 14001:2015 and ISO 15378:2017, with a Drug Master File (DMF 18100) and CFDA registration; certificate numbers are on the quality page.
Forms of supply
Serum vial seals ship Regular (non-sterile), Ready-to-Use or Ready-to-Sterilize. Ready-to-Use seals are washed and assembled in the ISO Class 8 cleanroom, double-lacquered, gamma or ETO sterilized and double-bagged for aseptic areas. Shelf life is 3.5 years before capping for non-irradiated seals, plus 5 years after capping, and 2 years before capping for Ready-to-Use. Tyvek bagging is available. Colour, finish (glossy, matte, embossed or printed) and marking are set per order. Minimum order quantities, pricing and lead times are available on request.
Applications
Serum vials are the default presentation for routine liquid injectables, multi-dose vaccines, anesthetics, diluents and veterinary products, and colour-coded flip-off seals are how most sites differentiate strength on the line. The 20 mm finish covers the bulk of that volume; 13 mm suits small-volume fills and 28 to 34 mm the larger multi-dose containers. The applications hub maps drug type to closure choice.
Frequently asked questions
What is a serum vial seal?
A serum vial seal is the aluminium closure crimped over the rubber stopper of a serum vial, a glass injection vial with a flanged crimp-top neck used as a multi-dose container for a liquid drug. The stopper forms the sterile barrier against the glass and the seal holds that compression for the shelf life of the product, while giving tamper evidence when the vial is first opened.
What sizes do serum vial seals come in?
Autofits makes serum vial seals in 13, 20, 28, 32 and 34 mm. The size refers to the vial’s neck finish rather than its fill volume, so vials of different volumes can share the same seal size. There is no 30 mm size in the range. The 20 mm finish is the most widely used for injectable vials.
What is the difference between a serum vial and a lyophilisation vial?
Usually the same glass container with the same neck finish; the difference is the stopper and the sequence. A serum vial is fully stoppered at fill and crimped straight away. A lyophilisation vial uses a two-leg stopper held half-seated so water vapour can escape during freeze-drying, then seated inside the chamber and crimped after the cycle finishes.
Which seal type should I use on a multi-dose serum vial?
The flip-off design is the usual choice: the plastic button lifts to expose a small central injection point while the aluminium stays crimped, so the closure keeps holding the stopper down between doses. Tear-off and tear-down designs remove more of the closure and suit single-entry or oral presentations.
How many serum vial seals come in a box?
Standard packing is 15,000 per box at 13 mm (5,000 in each of three bags), 6,000 at 20 mm, 3,000 at 28 mm and 1,400 at 32 mm, in a 420 × 270 × 320 mm shipper. Packing for 34 mm is quoted on request, and Tyvek bagging is available as an alternative.
Related reading
- Vial seals by size, 13 mm to 34 mm
- FlipTop® Optima flip-off seals
- Tear-off seals (all-aluminium)
- FlipTop® Tear-Down seals
- ISO 8362-1: injection vials made of glass tubing
- Single-dose vs multi-dose vials
Sources
- ISO: ISO 8362-1, Injection containers and accessories, Part 1: Injection vials made of glass tubing (https://www.iso.org/)
- ISO: ISO 8362-6, Injection containers and accessories, Part 6: Caps made of aluminium-plastics combinations for injection vials (https://www.iso.org/)
- ISO: ISO 15378, Primary packaging materials for medicinal products, GMP requirements (https://www.iso.org/standard/70729.html)
- Autofits engineering drawings and FlipTop Seals dossier (internal, on file)
*Last updated: 2026-08-18. This page is general technical and product information, not regulatory or compliance advice; confirm current standard editions, material specifications and your own specification with the Autofits technical team and the issuing bodies.*
