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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. Duran Group

    Guko/EPDM, 29x16x9mm 10 pcs.

    SKU: DU292021709
  2. Duran Group

    Guko/EPDM, 36x22x15mm 10 pcs.

    SKU: DU292022302
  3. Duran Group

    Guko/EPDM, 44x27x19mm 10 pcs.

    SKU: DU292022705
  4. Duran Group

    Guko/EPDM, 53x33x24mm 10 pcs.

    SKU: DU292023204
    In Stock
  5. Duran Group

    Guko/EPDM, 63x43x33mm 10 pcs.

    SKU: DU292023607
    In Stock
  6. Duran Group

    Pouring ring 5 pcs., 5 pcs.

    SKU: DU1088678
    In Stock
  7. Duran Group

    Pouring ring/PP, green 10 pcs., 10 pcs.

    SKU: DU1089911
    In Stock
  8. Duran Group

    Pouring ring/PP, gray 10 pcs., 10 pcs.

    SKU: DU1089914
    In Stock
  9. Duran Group

    Pouring ring/PP, yellow 10 pcs., 10 pcs.

    SKU: DU1089917
    In Stock
  10. Duran Group

    Pouring ring GLS 80 10 pcs., 10 pcs.

    SKU: DU1160166
  11. Duran Group

    Pouring ring, PTFE, 5 pcs.

    SKU: DU1167307
    In Stock
  12. Duran Group

    Stopper NS 24/29 for WERTEX safety connectors

    SKU: DU247960304
  13. Duran Group

    PE plastic stopper 29/32 10 pcs., 10 pcs.

    SKU: DU292040903
    In Stock
  14. Duran Group

    O-ring/silicone for flat flange-vessel to fit flange DN 200, 5 pcs.

    SKU: DU292256106
    In Stock
  15. Duran Group

    Pouring ring/PP, blue for DIN-thread GL 32, 10 pcs.

    SKU: DU292421907
    In Stock
  16. Duran Group

    Pouring ring/PP, blue for DIN-thread GL 45, 10 pcs.

    SKU: DU292422809
    In Stock
  17. Duran Group

    Pouring ring/ETFE, red for DIN-thread GL 32, 10 pcs.

    SKU: DU292441909
    In Stock
  18. Duran Group

    Pouring ring/ETFE, red for DIN-thread GL 45, 10 pcs.

    SKU: DU292442802
    In Stock
  19. Duran Group

    Seal PTFE-coated, GL 14 for red screw caps, 10 pcs.

    SKU: DU292480805
    In Stock
  20. Duran Group

    Seal PTFE-coated, GL 18 for red screw caps, 10 pcs.

    SKU: DU292481107
    In Stock
  21. Duran Group

    Seal PTFE-coated, GL 25 for red screw caps, 10 pcs.

    SKU: DU292481304
    In Stock
  22. Duran Group

    Seal PTFE-coated, GL 32 for red screw caps, 10 pcs.

    SKU: DU292481904
    In Stock
  23. Duran Group

    Seal PTFE-coated, GL 45 for red screw caps, 10 pcs.

    SKU: DU292482806
    In Stock
  24. IDL GmbH

    Gray stopper made of butyl rubber 100 pcs.

    SKU: ID1200420220
    In Stock
  25. IDL GmbH

    VOLL-STOPFEN GB SE 41 D 34X 41X35 MM 203.041

    SKU: ID203041
    In Stock
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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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