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Round Bottom Flasks

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  • 250mL Round Bottom Receiving Flask - 1 neck 24/40

    250mL Round Bottom Receiving Flask - 1 neck 24/40

    USA Lab
    RBF250ML1N
    $20.00
    Our 250mL 24/40 1 Neck Round Bottom Flask is constructed with 3.3 Borosilicate Glass and a 24/40 neck for a durable, common-size receiving flask to use.   Capacity: 250mL Neck Size: 24/40 Necks: 1 SKU: RBF250ML1N     We ship all...
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  • 24/40 Heavy Wall 250mL Round Bottom Receiving Flask - 2 neck

    24/40 Heavy Wall 250mL Round Bottom Receiving Flask - 2 neck

    USA Lab
    250RBF2NECK
    $20.00
    Our 250 mL 24/40 2 Neck Round Bottom flask is constructed with 3.3 Borosilicate glass and a 24/40 neck for a durable, common size receiving flask to use.   Capacity: 250mL Neck Size: 24/40 Necks: 2 SKU: N4     We ship all glassware...
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Round-Bottom Flasks From USA Lab

Durable, Heat-Resistant Glassware for Distillation and Reaction Systems

Round-bottom flasks are the workhorses of any chemistry lab. Designed for uniform heating and smooth mixing, they're essential for distillation, reflux, and reaction setups. USA Lab offers a complete range of single-, double-, and triple-neck borosilicate flasks that deliver excellent heat resistance, strength, and precision.

Designed for Uniform Heating and Versatile Use

Borosilicate 3.3 Glass

Engineered to withstand thermal stress and chemical exposure to perform reliably during heating, cooling, and daily solvent use.

Multiple Neck Configurations

Choose from 1-, 2-, or 3-neck designs to suit your apparatus, making it easy to connect condensers, thermowells, addition funnels, or probes.

Ground-Glass Joints

24/40 and 34/45 standard taper joints ensure leak-free compatibility with common lab condensers, adapters, stoppers, and vacuum systems.

Heavy-Wall Options

Added strength for vacuum or high-temperature operations, providing extra confidence when working under reduced pressure or when uniform heating is essential for reaction control.

Compare Round-Bottom Flask Options

Capacity Models Joint Sizes
250mL 1-Neck Flask

2-Neck Heavy-Wall Flask
24/40
500mL 1-Neck Flask

2-Neck Flask

1-Neck Spherical Joint Flask
24/40

35/20
1L 1-Neck Flask

2-Neck Flask
24/40
2L 1-Neck Flask

2-Neck Flask
24/40
5L 1-Neck Flask

2-Neck Flask

3-Neck Flask
24/40 and 34/45

2 – 24/40 and 1 – 34/45
10L 3-Neck Flask 1 – 24/40 and 2 – 34/45

Practical Design for Reliable Operation

  • Smooth curved base — Promotes even heat transfer and prevents localized boiling.
  • Precision joints — Provide airtight seals for vacuum or distillation connections.
  • Thick glass walls — Offer stability and durability under repeated thermal cycling.
  • Easy compatibility — Pairs with USA Lab mantles, condensers, and adapters.

Choosing the Right Flask for Your Work

  • Performing basic distillation or heating tasks? → A single-neck flask keeps things simple.
  • Need access ports for thermometers or gas inlets? → Go with a double- or triple-neck design.
  • Working at larger volumes? → Choose a 5L or 10L flask for high-capacity processing.
  • Running under vacuum? → Use heavy-wall options for added safety and strength.

Why Choose USA Lab Round-Bottom Flasks

  1. Multiple neck and joint options for flexible configurations.
  2. Compatible with all standard USA Lab distillation and heating equipment.
  3. Supported by fast U.S. shipping and responsive technical help.

Equipment That Complements Your Round-Bottom Flasks

Pair your flasks with: