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Rings and stoppers are useful aids in the daily lab routine. Manufacturers like Bohlender, Deutsch&Neumann, Bürkle and Duran produce stoppers and rings for various types of vessels, flasks and valves. Stoppers are made of fluoroplastics (e.g. PTFE), silicone or glass. Further stoppers are available in numerous shapes with variable top and bottom diameter, with a middle hole or a lamella-like grinding.  

Here you find further information on fluoroplastics

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Rings & Stoppers

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  1. Agilent Technologies

    Gaskets wash Seal6 pcs.

    sku: AG5062-2484
  2. Hirschmann

    SILICOSEN natural C55

    sku: HI8905755
  3. Supelco

    SEALING RESIN, 5GM, 1 pc

    sku: SU23817
  4. Hirschmann

    Poly stopper (PE) NS 34/35

    sku: HI8900290
  5. Hirschmann

    Poly stopper (PE) NS 45/40

    sku: HI8900293
  6. Hirschmann

    Silicone-stopper SILICOSEN T10 10 pcs.

    sku: HI8905510
  7. Hirschmann

    Silicone-stopper SILICOSEN T12 10 pcs.

    sku: HI8905512
  8. Hirschmann

    Silicone-stopper SILICOSEN T15 10 pcs.

    sku: HI8905515
  9. Hirschmann

    Silicone-stopper SILICOSEN T17 10 pcs.

    sku: HI8905517
  10. Hirschmann

    Silicone-stopper SILICOSEN T19 10 pcs.

    sku: HI8905519
  11. Hirschmann

    Silicone-stopper SILICOSEN T22 10 pcs.

    sku: HI8905522
  12. Hirschmann

    Silicone-stopper SILICOSEN T24 10 pcs.

    sku: HI8905524
  13. Hirschmann

    SILICOSEN natural T28

    sku: HI8905528
  14. Hirschmann

    Silicone-stopper SILICOSEN T32 10 pcs.

    sku: HI8905532
  15. Hirschmann

    SILICOSEN natural T38

    sku: HI8905538
  16. Hirschmann

    Silicone-stopper SILICOSEN T42 10 pcs.

    sku: HI8905542
  17. Hirschmann

    Silicone-stopper SILICOSEN T52 10 pcs.

    sku: HI8905552
  18. Hirschmann

    SILICOSEN natural T66

    sku: HI8905566
  19. Hirschmann

    SILICOSEN natural T76

    sku: HI8905576
  20. Hirschmann

    Silicone-stopper SILICOSEN L12 10 pcs.

    sku: HI8905612
  21. Hirschmann

    Silicone-stopper SILICOSEN L17 10 pcs.

    sku: HI8905617
  22. Hirschmann

    SILICOSEN natural L22

    sku: HI8905622
  23. Hirschmann

    SILICOSEN natural C20

    sku: HI8905720
  24. Hirschmann

    SILICOSEN natural C30

    sku: HI8905730
  25. Hirschmann

    SILICOSEN natural C40

    sku: HI8905740
  26. Hirschmann

    SILICOSEN natural C65

    sku: HI8905765
  27. Hirschmann

    SILICOSEN green S28

    sku: HI8905828
  28. Hirschmann

    SILICOSEN green S35

    sku: HI8905835
  29. Hirschmann

    SILICOSEN green S40

    sku: HI8905840
  30. Hirschmann

    Hollow glass stopper, clear glass, NS 14/23

    sku: HI8900370
  31. Hirschmann

    Hollow glass stopper, clear glass, NS 29/32

    sku: HI8900386
  32. ProSense

    O-ring Vision, 1 pc/PAK

    sku: PRPS91-425-045
  33. ProSense

    O-Ring, 3/8''ID x 5/8''OD, Chuck Head, 10 pc/PAK

    sku: PRPS91-425-003
  34. ProSense

    O-ring, 7 pc/PAK

    sku: PRPSD100-4455
  35. ProSense

    O-Ring, Spindle, Vision, 10 pc/PAK

    sku: PRPS91-425-044
  36. ProSense

    O-Rings, Home Port Sealing, AutoFill, 16 pc/PAK

    sku: PRPS61-207-722
  37. Agilent Technologies

    Tip seal replacement kit, for IDP-15 vacuum pump

    sku: AG5190-9613
  38. ProSense

    Centering Ring for Erweka

  39. ProSense

    Centering Ring for Hanson SR8/SR6

  40. ProSense

    Centering Ring for Hanson SR8

  41. ProSense

    Centering Ring for Logan

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Fluoroplastics: Rings & Stoppers made of PTFE, FEP, PFA etc.

Fluoroplastics belong to the family of thermoplastics. The higher the fluoric content, the better the chemical and thermal capacity of fluoropolymers. A number of characteristics makes fluoroplastics an ideal material for rings and stoppers. Unique properties are:

• universal chemical resistance,
• high thermal load capacity (-200 °C up to +260 °C),
• resistance to all sterilisation temperatures,
• resistance to environmental changes (weather, light),
• ultra-low friction coefficient and
• UV-resistance.

Further, accessories made of fluoroplastics are
• non-flammable,
• non-adhesive,
• unbreakable,
• physiologically safe and
• inert, without taste or odour.

In particular, the chemical and thermal resistance of PTFE is remarkable (-260°C up to +300°). The permanent temperature resistance depends on the load, so PTFE can be used from -200°C to +260°C at moderate mechanical load. PTFE lab equipment, e.g. hoses, magnetic stirring bars, bottles, or stirrer shafts, has a white appearance, a non-adhesive surface and extraordinary slip characteristics.

The chemical and mechanical properties of FEP are similar to those of PTFE. However, the upper limit of the permanent working temperature is lower (+205° C). FEP lab supply, e.g. hoses, is translucent to transparent and non-porous.

PFA has similar chemical and thermal characteristics to PTFE. PFA labware, e.g. hoses, bottles, or round-bottom flasks, is translucent to transparent, non-porous and particularly useful in high-purity work.

PP however does not belong to the family of fluoroplastics. PP is autoclavable (at +121° C) and has good mechanical and chemical properties almost up to its softening point. Lab supply made of PP, e.g. olives for stopcocks and valves or also lab furniture, is unbreakable and an economical alternative.

Cleaning of Fluoroplastics

Due to their smooth, non-wetting surface, all fluoroplastics (PTFE, PFA and FEP) can easily be cleaned. However, abrasive scouring agents might damage the surface and result in a milkiness of the vessels. All neutral detergents (pH 7) are suitable, for a stronger contamination an alkaline detergent up to pH 12 is recommended. Vessels should only be cleaned or dryed in laboratory washing machines when they are completely opened. Here you find a selection of cleaners and disinfectants as well as further information. Vessels made of PTFE, PFA or FEP can be autoclaved or sterilised at +121° C. To avoid deformation or destruction, all vessels with screw covers or stoppers have to be open while being autoclaved. Pressurisation (from inside) should be avoided, too due to the thin walls of standard PTFE, PFA or FEP bottles.

Duran Stoppers made of Borosilicate Glass

Stoppers made of borosilicate glass by Duran are an alternative to stoppers made of fluoroplastics. Borosilicate glass 3.3 is resistant to water, neutral and acid solutions, concentrated acids and acid mixtures, chlorine, bromine, iodine and organic substances. Further, borosilicate glass endures temperatures over 100° C and is universally applicable. Hence Duran glass is suitable ideally for the application in laboratories. Only HF-alkylation, concentrated phosphoric acid and strong alkali in combination with high temperatures (>100°C) lead to glass corrosion. For any other application areas e.g. Duran semi-hollow glass flat-head stoppers are available at Analytics-Shop.com.

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