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Quality has a name: DURAN®
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Frequently asked questions - FAQs
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What is the maximum temperature that DURAN® can withstand??
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The maximum temperature at which DURAN®can be used is 500°C. Its transformation temperature (i.e. the temperature at which it changes from its elastic-brittle state into a viscous state) is 525 °C.
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What temperature variations can DURAN® be exposed to?
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DURAN® is very resistant to temperature variations, i.e. it has a high thermal shock resistance. Temperature differences should, however, be kept to a maximum of 100°C. For example, frozen substances can be thawed out in DURAN® containers by placing the container in a warm liquid, but the temperature of the container should not be more than approximately 100°C higher than that of the frozen substance. [back]
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How chemically resistant is DURAN®?
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Glass, particularly DURAN® borosilicate glass, has a greater resistance to chemical attack than any other known material. DURAN® is highly resistant to water, acids, saline solutions, organic substances and also halogens such as chlorine and bromine. Its resistance to alkaline solutions is also relatively high. Details are as follows:
Hydrolytic resistance to DIN-ISO 719 (98°C):
Hydrolytic resistance grain class ISO 719-HGB 1, which equates to hydrolytic resistance class 1 (1 is the most resistant class)
Acid resistance:
Acid class 1 (to DIN 12 116) i.e. acid attack mechanisms have no effect in practice, since the loss of wall thickness is virtually negligible.
Alkali resistance:
Alkali resistance class DIN 52 322-A2, i.e. for example when using 1mol/l NaOH (pH value approx. 14) at 50°C, the glass erosion after 25 years is < 1mm.
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What temperature can soda-lime glass be subjected to?
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Normal soda-lime glass can be subjected theoretically to approximately 450°C. However, allowance must be made for the fact that the thermal shock resistance of soda-lime glass is only about one-third of that of DURAN® borosilicate glass; thus, it is not advisable to use soda-lime glass in applications where thermal stress is likely to be encountered.
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Can be DURAN® used in a microwave?
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Yes, DURAN® can be used in microwave appliances. [back]
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What is the difference between DURAN®, Boro 3.3, Boro 4.1 and other types of glass?
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DURAN® is a borosilicate glass 3.3. The term 3.3 represents the linear thermal coefficient of expansion. The lower this is, the more resistant the glass is to variations in temperature. Þ = 3.3 therefore means that the glass expands by 3.3 *10-6 units of length per kelvin, in a temperature range from 20°C to 300°C. With large coefficients of expansion temperature differences cause stresses in the glass when it is heated and this can result in breakage. [back]
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What does the nominal diameter (DN) mean?
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The nominal diameter (DN), also known as nominal bore, refers to the internal diameter of a cylindrical body, e.g. the internal diameter at the flange of a desiccator. In such cases the stated size is only an approximate figure and the actual internal diameter is normally bigger. With a DN 200 desiccator the actual internal diameter is 222 mm. [back]
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How can I determine or measure the nominal diameter?
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On a desiccator you can measure the nominal diameter with a caliper rule (using the internal measurement legs) or a ruler. [back]
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How accurate are the printed scales on basic items of DURAN® laboratory glassware? (beakers, Erlenmeyer flasks, laboratory bottles)
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In the case of DURAN® beakers, laboratory bottles, etc. the bottom and top marks on the scales are accurate to ± 10%. [back]
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What does APPROXIMATE VOLUME mean?
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Approximate volume means that when the item is the filled up to the particular mark on the scale, the volume is approximately the amount indicated. There are no standards laid down from which maintaining a specific accuracy can be derived![back]
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Are the general DURAN® laboratory glass items or other items certified (DIN/ISO)?
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It can be said in general that it is not our products that are certified; however, the Industrial Glass Division based in Mainz is certified to DIN EN ISO 9001 by TÜV Cert. Specifications are available for our DURAN® products. [back]
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Are safety data sheets issued for DURAN® products?
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Safety data sheets are required to be produced only for (dangerous) substances or products. Information regarding the glass is contained in a glass specification. Additional information about individual products can be found in other relevant specifications.[back]
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How temperature resistant are the red and blue caps on the laboratory bottles? (temperature resistance of the materials)
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- Blue caps (PP): Melting point: 165° (sharply defined). Processing temperature: approximately 250°. Ignition temperature: 330°. Decomposition temperature: 350°. Recommendation: use up to 140°C is possible.
- Red caps (Valox): Melting point: from approximately 220° to 250° (gradual transition, softening). Processing temperature: approximately 280° to 300°. Ignition temperature: 360°. Recommendation: use up to 180°C is possible.
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Additional data on all plastics and colors (safety data sheets, specifications...) are available on request. [back]
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Are caps also available for NMR tubes in different colors?
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Caps for NMR tubes are enclosed in a standard color assortment in the pack with the tubes:
DURAN Economic – 250 to a pack with 50 caps
each in red, yellow, blue, green, black;
DURAN Professional – 250 to a pack with 50 caps
each in red, yellow, blue, green, black;
DURAN Scientific – 5 to a pack, already fitted with a blue cap.
Caps can also be supplied separately; price, minimum quantity and delivery time are available on request. [back]
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How are amber laboratory bottles produced (round laboratory bottles,
Cat. No. 21 806)? What effect does the amber tint have on the properties of the bottle?
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In the amber tinting process the glass is coated on the outside with a diffusion color. It is then heat treated for several hours during which time it is colored amber by ion exchange. The ion exchange penetrates the external surface to a depth of about 0.1mm. After being heat treated the glass vessels are washed and no residue is left on the glass. Since the color is applied on the outside, it has no adverse effect on the contents. This applies irrespective of the temperature of use. [back]
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Where can I get more information?
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You can find additional information under the heading technical info, in the
DURAN® catalog or by calling us at Contact
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