Lab Plastic Stands & Test Tube Racks

Test tube racks are made with holes sized for specific tube outer diameters. Standard 16 mm holes suit most test tubes. Centrifuge tube racks have 28 mm holes for 50 ml tubes and 17 mm holes for 15 ml tubes. If the tube is too small, it will fall through; too large and it will not seat properly. Check tube outer diameter against rack hole size before purchasing.

Racks are available with 6, 10, 20, 40, or more positions. Choose based on the number of samples you run simultaneously. A 20-position rack accommodates a typical school class experiment; a 40-position rack suits high-throughput sample preparation in a research or diagnostic lab.

Flask stands are sized by the diameter of the equator of the round-bottom flask they support. A 100 ml round-bottom flask has a much smaller equator diameter than a 5 000 ml flask. Order the flask stand size that matches the flask volume you use most frequently, or order an assortment. A stand that is too large will let the flask tilt and tip.

PP racks can be autoclaved at 121 degrees Celsius and are the correct choice for microbiological and cell culture work where sterile sample organisation is required. Polystyrene racks cannot be autoclaved and will melt. Natural rubber flask stands can be autoclaved but may harden after repeated cycles. Silicone rubber flask stands are the most durable for repeated autoclave use.

Standard plastic test tube racks are made with 16 mm diameter holes that fit the most common test tube outer diameters of 13 mm to 16 mm. Some racks have multiple hole sizes in different rows to accommodate a range of tube sizes simultaneously. If you use non-standard tubes such as 25 mm culture tubes or 50 ml centrifuge tubes, you will need a rack specifically designed for those diameters.

Natural rubber flask stands are dense, grippy, and resist slipping on the bench surface. They are suitable for room temperature and mild heating up to approximately 80 degrees Celsius. Silicone rubber flask stands are heat resistant to 250 degrees Celsius and can hold flasks that have just been heated, making them suitable for post-heating rest and for use near hot plates and heating mantles. Silicone stands are also more resistant to chemical spills.

Polypropylene (PP) test tube racks can be autoclaved at 121 degrees Celsius and are the standard choice for microbiology and cell culture labs. Polystyrene (PS) racks cannot be autoclaved and will deform. Check the material label on the rack before placing it in an autoclave. After repeated autoclaving, inspect PP racks for brittleness or discolouration and replace if degraded.

Standard plastic test tube racks are available in 6-position, 10-position, 20-position, and 40-position configurations. The most common size for school and general lab use is 20 positions, which accommodates a full class experiment series. High-throughput research labs typically use 40-position or 96-well format racks. Choose based on how many parallel samples you run in a single session.

Only if the hole sizes match. Centrifuge tube racks have 28 mm holes for 50 ml centrifuge tubes and 17 mm holes for 15 ml centrifuge tubes. Standard test tubes have an outer diameter of 13 mm to 16 mm and will fall through 28 mm holes. Use a rack specifically sized for the tube type you are using to ensure the tubes sit securely and do not tip.