Breckland Scientific 2021 Catalogue

Test Tubes

Test Tube Information

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Breckland stocks three of the most reliable brands of test tubes available, as follows: Kimble - A brand of DWK Life Sciences, one of the world’s leading manufacturers of premium lab glassware. PYREX - The premium brand of DWK Life Sciences Samco - A premium brand of S Murray & Company, still a UK family owned company after more than 100 years in business.

PLEASE BE AWARE that continuous intensive heating of just one area of a test tube, beaker etc. may result in softening and deformation of the glass, regardless of the glass type or brand. It is important to keep test tubes etc. moving slightly within a flame, to distribute the heat more evenly and prevent the build-up of hot spots which could deform the glass (beakers are usually placed on a wire gauze before heating, which spreads the heat more evenly). It is good practice to bring any glassware up to temperature gradually in a direct heat source, to avoid the possibility of thermal shock and cracking.

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Glass Types: Soda Glass - this has traditionally been used for bottles and general lab glassware. It is a more economical option but is not suitable for direct heating with a Bunsen burner etc. Neutral Borosilicate - more economical than borosilicate, this has a high chemical resistance and is suitable for use with strong acids & alkalis. It can withstand moderate heating, but it is best to avoid sudden temperature changes e.g. by placing a cold test tube directly into a hot Bunsen flame - gradually heat at first before more concentrated heating. Borosilcate Glass - this is the most suitable glass type to use when heating in a direct Bunsen flame. It is the most heat and thermal shock resistant of the standard glass types and is highly resistant to strong chemicals such as acids & alkalis.

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Ignition Tube, Test Tube or Boiling Tube? Ignition Tube, Test Tube and Boiling Tube are terms loosely applied to different sizes of test tubes. Ignition Tubes - the very small borosilicate tubes e.g. 75 x 10mm which are often used for intensive heating of samples. They are sometimes discarded after use, due to the difficulty of cleaning or because of damage to the glass. Test Tubes – the medium sized tubes used for many applications, which are typically 125 x 16mm or 150 x 16mm. Boiling Tubes – the larger sized tubes often used for heating solutions etc., which are typically 150 x 24mm.

GLASS INFORMATION Glass used for test tubes and the properties of each manufacturers’ glass affects the performance of the product from which it is made. Generally the lower the coefficient of expansion, the more resistant the glass is to thermal shock i.e cracking. The higher the softening and working point, the less likely it is to deform if left in a bunsen flame.

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Softening Point (°c)

Working Point (°c)

Coefficient of Expansion (cm/cm/°c)

Glass Type

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Soda Glass

89 x 10 -7

725 770 827 825 825

1040 1160 1255 1260 1260

Neutral Borosilicate 50 x 10 -7 Kimble Borosilicate 32 x 10 -7 DURAN Borosilicate 33 x 10 -7 Samco Borosilicate 33 x 10 -7

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Test Tube Holders

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1 TEST TUBE HOLDER - BRASS With wooden handle. Cat No. Description

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Price Per

TTU-550-100 Test Tube Holder - Brass

4.37 ea.

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2

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2 TEST TUBE HOLDER - SPRING Cat No. Description

Price Per

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TTU-600-100 Test Tube Holder - Spring

5.44 10

3 TEST TUBE HOLDER - WOODEN Clothes Peg style. Up to 19mm test tubes. Cat No. Description Price Per TTU-650-100 Test Tube Holder- Clothes Peg 6.16 10

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Test Tubes Holders - Brass and Spring Types

Test Tubes Holder - Clothes Peg Type

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441

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