PYREX CORNING 4321A-250 Glass Neck Round Bottom Boiling 250ML 14/20 Flask

( Brand: Pyrex Corning ), ( Manufacturer Part Number: 4321A-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 14/20 Short Neck Round Bottom Boiling Flask

The **Corning Pyrex 4321A-250 250ml 14/20 Round Bottom Boiling Flask** is a precision-engineered laboratory glassware essential for a wide range of chemical, pharmaceutical, and scientific applications. Crafted from **borosilicate glass (Type 3.3)**, this flask exemplifies durability, chemical resistance, and thermal stability, making it ideal for demanding experiments that involve heating, boiling, or refluxing. The **250ml capacity** strikes a balance between versatility and practicality, accommodating moderate-scale reactions while maintaining sufficient headspace for efficient stirring, distillation, or solvent evaporation. Its **14/25 ground joint (14/20 neck)** ensures a secure, leak-proof connection to compatible glassware such as condensers, adapters, or reaction vessels, facilitating seamless integration into complex setups like reflux systems or rotary evaporators. The **round bottom design** optimizes heat distribution and minimizes dead zones, reducing the risk of localized overheating or product degradation during prolonged heating. The **smooth, polished surface** of the Pyrex glass minimizes adsorption of reactive substances, ensuring accurate results and easy cleaning, while its **high thermal shock resistance** allows for rapid temperature changes without compromising structural integrity. Whether used in academic research, industrial synthesis, or routine laboratory procedures, this flask combines reliability with performance, making it a cornerstone of modern chemical experimentation. Its **sterilizable and autoclavable** properties further extend its utility in microbiological and pharmaceutical workflows, where sterility is paramount. Built to endure rigorous use, the Corning Pyrex 4321A-250 flask is a testament to quality engineering, offering both precision and longevity for scientists who demand nothing less than excellence in their glassware.

**Pros and Cons of Buying a Pyrex Corning 4321A-250 (250 mL, 14/20 Neck Round Bottom Boiling Flask)**

### **Pros**

1. **Durability and Chemical Resistance** Pyrex glass is known for its high thermal shock resistance and ability to withstand repeated heating and cooling cycles without cracking. It is also resistant to most common laboratory chemicals, making it suitable for a wide range of reactions.

2. **Precision and Uniform Heating** The round bottom design ensures even heat distribution when used with a heating mantle or oil bath, which is critical for accurate and consistent reactions, especially in distillation, reflux, or boiling applications.

3. **Compatibility with Standard Laboratory Equipment** The 14/20 joint size is a common standard in laboratory glassware, allowing it to be easily connected to condensers, adapters, and other accessories without the need for additional adapters.

4. **Long Lifespan** High-quality borosilicate glass (like Pyrex) is designed to last for years with proper care, making it a cost-effective investment for frequent use in academic, industrial, or home laboratory settings.

5. **Safety** Unlike plastic or lower-quality glass, Pyrex does not leach harmful substances when exposed to heat or chemicals, reducing contamination risks in experiments.

6. **Versatility** Suitable for a variety of laboratory techniques, including boiling, distillation, extraction, and synthesis, making it a versatile tool for chemists, students, and hobbyists.

7. **Easy to Clean** The smooth glass surface resists staining and can be cleaned thoroughly with solvents, detergents, or even sonication, ensuring reproducibility in experiments.

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### **Cons**

1. **Fragility Despite Durability** While Pyrex is more resistant to thermal shock than regular glass, it is still brittle. Dropping it or subjecting it to sudden impacts can cause it to shatter, potentially damaging the flask and creating a safety hazard.

2. **Weight** The thick borosilicate glass makes the flask heavier than plastic alternatives, which can be cumbersome for frequent handling, especially in large quantities or when working with limited mobility.

3. **Cost** Compared to cheaper plastic or lower-grade glassware, Pyrex is more expensive upfront. However, its longevity often justifies the cost for serious users.

4. **Limited Flexibility in Size** If your needs change and you require a different volume (e.g., 100 mL, 500 mL), you may need to purchase additional flasks, increasing long-term costs.

5. **Maintenance of Joints** The 14/20 joint must be kept clean and free of debris to ensure a proper seal. Over time, joints can wear out or become damaged, requiring replacement or careful cleaning to maintain functionality.

6. **Not Ideal for High-Pressure Applications** While Pyrex is strong, it is not designed for high-pressure reactions (e.g., in autoclaves or pressure vessels). For such applications, specialized glassware or metal reactors are required.

7. **Potential for Scratches and Etching** Prolonged use with abrasive cleaning tools or harsh chemicals can scratch or etch the glass surface, which may affect its appearance and, in extreme cases, its performance.

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### **Conclusion**

The **Pyrex Corning 4321A-250 (250 mL, 14/20 neck round bottom boiling flask)** is an excellent investment for anyone engaged in serious laboratory work, whether in academia, industry, or advanced home experimentation. Its superior durability, chemical resistance, and compatibility with standard lab equipment make it a reliable choice for boiling, reflux, and distillation applications. While it has some drawbacks such as weight, fragility, and cost these are outweighed by its performance and longevity for most users.

For **casual or occasional users** who work with small volumes or low-risk applications, a lower-cost alternative (e.g., plastic or lower-grade glass) might suffice. However, for **serious chemists, students, or hobbyists** who prioritize precision, safety, and durability, the Pyrex flask is highly recommended.

If you require a **high-quality, long-lasting, and versatile** boiling flask for laboratory or experimental work, the **Pyrex Corning 4321A-250** is an excellent purchase. Ensure you handle it with care to avoid breakage and maintain its joints for optimal performance. If budget is a concern, consider starting with one flask and expanding your collection as needed.

Details:

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

part #: 4321a250 prices

• $21.99-$43.92

specifications plasticwarelabsuppy:

• brand: Pyrex Corning
• mpn: 4321a-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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• started: February 7, 2026
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• quantity: 12
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general plasticwarelabsuppy:

• condition: Used
• Medical, Lab Dental Supplies > Glassware Plasticware > Other Medical Lab Glassware

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• city: Cotati, California
• rating: 99.8%
• # reviews: 7387

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