PYREX CORNING 4320B-250 Glass Neck Round Bottom Boiling 250ML 19/22 Flask

( Brand: Pyrex Corning ), ( Manufacturer Part Number: 4320B-250 ), ( Intended Use/discipline: Biological Laboratory, Dental Laboratory, Medical Laboratory, Microbiological Laboratory, Physical Laboratory ), ( Country Of Origin: United States ), ( Unit Type: Unit ), ( Additional Information: Surplus Laboratory Consumable Supplies )

Review PYREX CORNING Glass 250ml 19/22 Short Neck Round Bottom Boiling Flask

The **Corning Pyrex 4320B-250 glass 250 mL 19/22 neck round bottom boiling flask** is a precision-engineered laboratory glassware essential for a wide range of chemical, biological, and pharmaceutical applications. Crafted from high-quality **borosilicate glass (Type 3.3)**, this flask is renowned for its exceptional thermal and chemical resistance, making it ideal for demanding processes such as distillation, reflux, extraction, and solvent recovery. The **250 mL capacity** provides a versatile working volume, accommodating moderate-scale reactions while maintaining sufficient headspace for efficient stirring, heating, or gas introduction. The **19/25 standard taper joint** ensures a secure, leak-proof connection with compatible glassware, including condensers, adapters, and ground glass stoppers, facilitating seamless integration into complex setups. The **round bottom design** optimizes heat distribution during boiling or heating, reducing hot spots and minimizing the risk of thermal stress or cracking critical factors in high-temperature applications. Additionally, the **smooth, durable glass surface** resists corrosion from aggressive solvents, acids, and bases, ensuring longevity and reliability even under rigorous conditions. Whether used in academic research, industrial synthesis, or routine laboratory procedures, this flask combines **durability, precision, and versatility**, making it a cornerstone of modern chemical experimentation. Its **clear, uncolored borosilicate construction** also allows for easy visualization of reactions, further enhancing its utility in processes requiring real-time monitoring. Built to withstand repeated autoclaving and sterilization, this flask adheres to stringent quality standards, providing researchers with confidence in its performance across a broad spectrum of applications.

### **Pros and Cons of Buying a Pyrex Corning 4320B-250 (250 mL, 19/22 Neck Round Bottom Boiling Flask)**

1. **Durability and Heat Resistance** Pyrex glass is known for its high thermal shock resistance, making it suitable for heating, cooling, and boiling applications without cracking. This flask can withstand repeated heating and cooling cycles, which is essential in laboratory settings.

2. **Chemical Inertness** Borosilicate glass (like Pyrex) is chemically inert, meaning it does not react with most reagents. This makes it safe for use with a wide range of solvents, acids, and bases without contamination.

3. **Precision and Clarity** The clear glass allows for easy visualization of reactions, ensuring accurate monitoring of processes such as distillation, reflux, or boiling.

4. **Standardized Dimensions** The 19/25 (or 19/22) joint size ensures compatibility with a wide range of laboratory glassware, adapters, and equipment, making it versatile for various setups.

5. **Long Lifespan** When properly cared for, Pyrex glassware can last for decades, making it a cost-effective investment for laboratories or home chemistry setups.

6. **Safety in High-Temperature Applications** Unlike plastic or lower-quality glass, Pyrex can handle boiling water, steam, and even moderate autoclaving (though not extreme pressure).

7. **Compatibility with Vacuum Systems** The round bottom design and proper joint size allow for use in vacuum distillation or filtration setups.

8. **Easy to Clean** Glass is non-porous, so it can be thoroughly cleaned with solvents, detergents, or even mild acid washes without degradation.

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1. **Fragility Compared to Plastic** While durable, glass is still brittle. Dropping it or subjecting it to sudden impacts can cause shattering, which is a risk in busy labs or home environments.

2. **Weight** Glass is heavier than plastic alternatives, which can make handling and transporting the flask cumbersome, especially for larger volumes.

3. **Limited Flexibility in Design** Unlike plastic or flexible tubing, glass cannot be bent or reshaped, limiting its use in certain custom setups.

4. **Cost** High-quality borosilicate glassware is more expensive upfront than some plastic or lower-grade glass alternatives, though it often proves cost-effective in the long run.

5. **Potential for Scratches and Etching** Prolonged use with abrasive cleaners or rough handling can lead to scratches, which may affect clarity and could become sites for chemical reactions or microbial growth.

6. **Not Suitable for Extreme Pressure** While Pyrex can handle standard atmospheric pressure and moderate vacuum, it is not designed for high-pressure applications (e.g., Parr reactors or extreme autoclaving).

7. **Breakage Risk in Rough Environments** In settings with frequent movement (e.g., fieldwork, mobile labs), the risk of accidental breakage increases.

8. **Requires Careful Handling During Heating** Uneven heating (e.g., direct flame without a heat-resistant pad) can cause thermal stress, leading to cracks or failure.

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The **Pyrex Corning 4320B-250 (250 mL, 19/22 neck round bottom boiling flask)** is an excellent choice for **laboratory, educational, or home chemistry applications** where durability, chemical resistance, and precision are critical. Its borosilicate glass construction ensures reliability in heating, boiling, and reflux operations, making it ideal for distillation, synthesis, or teaching experiments. However, its fragility and higher cost compared to plastic alternatives mean it is best suited for controlled environments where breakage risks are minimized.

- You need a **long-lasting, chemically inert** flask for **boiling, reflux, or distillation** in a laboratory or educational setting.

- You prioritize **clarity and precision** in monitoring reactions.

- You are willing to invest in **high-quality glassware** that will last for years with proper care.

- You require **portability or extreme durability** (e.g., fieldwork), in which case a **plastic or reinforced glass flask** might be preferable.

- Your budget is tight, and you can use a **lower-cost borosilicate flask** (though quality may vary).

- You need **high-pressure applications**, as standard Pyrex is not designed for such conditions.

For most **serious chemistry users**, this flask is a **strong recommendation** due to its balance of performance, safety, and longevity. Always handle it with care to avoid breakage and store it in a secure location.

Details:

See pictures for details. May show minor signs of use such as light residue. No chips or cracks noted throughout. GSR veers 1730 GS 9.9.4 1730 Used item in good condition.

part #: 4320b250 prices

• $38.98-$180.00

specifications plasticwarelabsuppy:

• brand: Pyrex Corning
• mpn: 4320b-250
• intended use/discipline: Biological Laboratory, Dental Laboratory, Medical Laboratory, Microbiological Laboratory, Physical Laboratory
• country of origin: United States
• unit type: Unit
• additional information: Surplus Laboratory Consumable Supplies

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• Medical, Lab Dental Supplies > Glassware Plasticware > Other Medical Lab Glassware

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• started: February 7, 2026

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