ER00447
White PTFE/White Silicone Septa, 20 mm Crimp-top Aluminium Cap, 9.5 mm Centre Hole, Economical type, 100/pk
Lead time 3-4 weeks, ships from the Czech Republic (EU)
€27.82 per pack of 100 €0.28 per cap
20 mm crimp caps and septa (ND20)
20 mm aluminium crimp caps for headspace vials, including blue magnetic and pressure-release caps, with 8, 9.5 or 10 mm centre holes, plus loose 20 × 3 mm septa in PTFE/silicone (-60 to 200 °C) and PTFE/butyl (-60 to 120 °C).
They seal 6-20 ml headspace vials for GC, in packs of 100. Items without a listed price are quoted on request; items not in stock have a lead time of 3 to 4 weeks.
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Products
ER00448
Nature PTFE/Nature Silicone Septa, 20 mm Crimp-top Aluminium Cap, 9.5 mm Centre Hole, Thicker cap, New Technology, 100/pk
Lead time 3-4 weeks, ships from the Czech Republic (EU)
€34.78 per pack of 100 €0.35 per cap
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The vial decides the cap. Match the neck and closure type first, then choose the septum material and the cap style.
Step 1: Match the cap to the vial neck
| Vial neck | Typical vials | Cap to order |
|---|---|---|
| 8-425 screw | 2 ml, 11.6 × 32 mm | 8 mm screw cap (ND8) |
| 9 mm short thread | 2 ml and 0.3 ml, 11.6 × 32 mm | 9 mm short-thread screw cap (ND9) |
| 11 mm crimp | 2 ml and 0.3 ml, 11.6 × 32 mm | 11 mm aluminium crimp cap (ND11) |
| 13-425 screw | 4 ml, 14.5 × 45 mm | 13 mm screw cap (ND13) |
| 15-425 screw | 8 ml and 12 ml | 15 mm screw cap (ND15) |
| 18 mm precision screw | 10 ml and 20 ml headspace | 18 mm magnetic screw cap (ND18) |
| 20 mm crimp | 6, 10 and 20 ml headspace | 20 mm crimp cap (ND20) |
| 24-400 screw | 20 to 60 ml EPA vials | 24 mm screw cap (ND24) |
Thread systems are not interchangeable: a 9 mm cap will not seal an 8-425 or 10-425 vial, even though the sizes look close. Crimp caps need a hand crimper, and a decapper to remove them.
Step 2: Septum material
| Septum | Use it for | Note |
|---|---|---|
| PTFE/silicone | Most HPLC and GC work, repeat injections | The PTFE face meets the sample; the silicone reseals after the needle is withdrawn |
| PTFE/silicone/PTFE | Samples that may contact both faces of the septum | PTFE on both sides for extra chemical resistance |
| PTFE only | Single injections | Very inert, but does not reseal after piercing |
| PTFE/butyl | Headspace GC and volatile samples | Butyl rubber has low gas permeability; rated for lower temperatures than silicone |
| PE foam liner | Closed caps for storage | Not intended for needle piercing |
Temperature ratings are on each product page. In this range, PTFE/silicone septa are listed for -60 to 200 °C and PTFE/butyl for -60 to 120 °C.
Step 3: Cap style
- Centre hole or closed top: caps with a centre hole leave the septum open to the needle; closed-top caps are for storage and transport.
- Pre-slit septa: easier needle entry, less coring and no vacuum in the vial during sampling. They reseal less well, so avoid them for volatile samples left in the tray for a long time.
- Bonded septa: the septum is fixed in the cap, so it cannot fall out or turn during handling.
- Magnetic caps: for autosamplers that pick up vials with a magnet, which is common in headspace GC.
- Pressure-release caps: 20 mm headspace caps that vent excess pressure when the vial is heated.
Caps and septa are sold in packs of 100. Order caps with vials: on EROHE, equal packs of 9 mm vials and caps get 5% off both. Not sure which cap fits your vial? Email sales@erohe-lab.com with the vial part number.
Questions buyers ask
PTFE/silicone or PTFE/butyl septa for headspace?
PTFE/butyl has lower gas permeability and suits volatiles, but is listed for up to 120 °C. PTFE/silicone is listed for up to 200 °C for hotter methods.
What is a pressure-release headspace cap for?
It vents excess pressure that builds up when the vial is heated, before it can become unsafe.
Do I need magnetic crimp caps?
Only if your headspace autosampler moves vials with a magnet. Otherwise plain aluminium caps work.
Which crimper do I need?
A 20 mm crimper. Hand crimpers and decappers are sized for one cap diameter.