A ground-glass stopper is the gold standard for solvent compatibility — but in a high-throughput teaching lab or a production QC environment, fumbling with stoppers that seize, chip, or go missing is a real operational cost. The SIBATA 2303A Series Volumetric Flask addresses this with a snap-cap closure engineered for fast, secure, one-handed operation while preserving the full Class A volumetric accuracy that analytical work demands. The borosilicate glass body and neck carry identical ASTM E-288 Class A certification and USP compliance as the glass-stopper 2306A Series — the only difference is the closure system. You get ±0.10mL accuracy at 100mL, machine-blown uniform wall thickness, a sharply defined graduation line, and "to contain" calibration at exactly 20°C. The snap cap adds drop protection by cushioning the neck from bench contact, and eliminates the stopper-matching problem when running multiple flask sizes simultaneously.Features and Benefits Full ASTM E-288 Class A certification — same accuracy as glass-stopper series: The snap-cap closure does not compromise volumetric accuracy. The 2303A Series carries identical Class A certification to the 2306A glass-stopper series, with the same tolerance values: ±0.05mL at 10mL, ±0.06mL at 25mL, ±0.10mL at 100mL, and ±0.40mL at 1000mL. Suitable for preparing primary standards, calibration solutions, and any quantitative analytical preparation requiring traceable volumetric accuracy. Snap cap included — fast, one-handed closure with drop protection: Each flask ships with a matching snap cap that secures with a single press and releases with a single lift. In high-volume settings — student benches, QC labs running many preparations simultaneously, or any workflow where speed of closure matters — this eliminates the per-flask overhead of threading and seating a ground-glass stopper. The snap cap also cushions the flask neck during incidental contact with bench surfaces, reducing the most common chipping failure point. Machine-blown borosilicate body with heavy-beaded, heavy-tubing neck: The flask body is machine-blown from Type 1 borosilicate glass with a low coefficient of thermal expansion, producing consistent wall thickness across every unit in the production run. The heavy-beaded neck profile is specifically designed for snap-cap engagement — providing the dimensional precision required for a secure, repeatable snap fit over the full service life of the flask. USP-compliant for pharmaceutical and compounding environments — snap-cap solvent limits apply: Like all SIBATA Class A volumetric flasks, the 2303A Series complies with United States Pharmacopeia glassware specifications. This makes it suitable for pharmaceutical QC, compounding, and regulated laboratory environments where USP compliance is audited — provided that the snap-cap material is compatible with the solution being prepared. For solutions requiring a fully inert closure (aggressive organic solvents, long-term storage), the glass-stopper 2306A Series is recommended instead. Calibrated "to contain" (TC) at 20°C with sharply defined graduation line: The single volumetric graduation mark is fired at uniform width into the glass neck — permanently visible and resistant to cleaning agents, solvents, and autoclaving. Calibration is TC at 20°C, marked on every flask. The large white marking square gives space for sample identification, concentration, date, and analyst initials. Autoclavable across all sizes: All eight sizes withstand standard autoclave conditions at 121°C, 15 psi, for 20-minute cycles. Remove the snap cap before autoclaving to prevent pressure buildup. This allows the flask body to be sterilized before use in biological or sterility-critical preparations, then capped after sterilization for storage of the prepared solution. Specifications Property Value SKU Series 2303A Series (2303A-10, 2303A-25, 2303A-50, 2303A-100, 2303A-200, 2303A-250, 2303A-500, 2303A-1000) Brand SIBATA Type Volumetric Flask, Class A, Snap Cap Calibration To Contain (TC) at 20°C (68°F) Accuracy Standard ASTM E-288 Class A; USP compliant Material Borosilicate Glass (Type 1) Closure Snap cap (included) Color Clear Country of Origin Taiwan Autoclavable Yes (remove cap before autoclaving) 10 mL Dims: 26 × 85 mm | Pack of 6 25 mL Dims: 37 × 110 mm | Pack of 6 50 mL Dims: 49 × 136 mm | Pack of 4 100 mL Dims: 58 × 164 mm | Pack of 4 200 mL Dims: 74 × 205 mm | Pack of 4 250 mL Dims: 78 × 225 mm | Pack of 4 500 mL Dims: 96 × 260 mm | Pack of 2 1000 mL Dims: 122 × 300 mm | Pack of 2 HTS Code 7017.20.0000 UNSPSC Code 41121803 Warranty 1 Year Laboratory Applications High-throughput analytical and QC labs: In environments where technicians prepare dozens of standards or solutions per shift, the snap-cap design reduces the per-flask handling time versus ground-glass stoppers. The snap cap stays with the flask by design — no searching for the right-size stopper when a bench has multiple flask sizes in use simultaneously. Class A accuracy is maintained throughout. Teaching labs — snap cap eliminates stopper-mismatch errors at student benches: The snap-cap closure is more robust against mishandling than a ground-glass stopper — student labs benefit from the drop cushioning and the lower risk of students using mismatched stoppers. Pack quantities of 6 (small sizes) and 4 (mid sizes) allow practical equipping of student benches at Class A accuracy without premium glass-stopper pricing. Standard solution preparation for aqueous and dilute-solvent applications: For preparing aqueous buffer solutions, water-based calibration standards, and dilute acid or base standards, the snap cap provides a practical, reliable seal. For concentrated organic solvents or long-term solvent storage, the glass-stopper 2306A Series is the appropriate choice — the snap-cap material has finite solvent exposure limits. Pharmaceutical compounding and QC at regulated volume sizes: USP compliance makes the 2303A Series suitable for licensed compounding pharmacies and pharmaceutical QC workflows preparing aqueous or compatible solutions. The 100mL and 250mL sizes are the most commonly required sizes for compounding standard preparations. Frequently Asked QuestionsIs the snap cap as accurate as a ground-glass stopper for volumetric work?Yes — the volumetric accuracy of the flask is determined by the glass body and the graduation line, not the closure. Both the 2303A (snap cap) and 2306A (glass stopper) Series carry identical ASTM E-288 Class A certification. The closure choice affects solvent compatibility and handling convenience, not the volume contained when filled to the graduation mark at 20°C.When should I choose the snap cap series vs. the glass stopper series?Choose the snap cap (2303A) for high-throughput workflows, teaching labs, aqueous or dilute solution work, and environments where faster closure and drop protection outweigh the need for full solvent inertness. Choose the glass stopper (2306A) when working with aggressive organic solvents, when long-term solution storage in the flask is required, or when a fully inert glass-on-glass seal is specified by your SOP or regulatory documentation.Can the snap cap be autoclaved along with the flask?Remove the snap cap before placing the flask in the autoclave. Autoclaving the cap in place can trap steam inside the flask and create pressure differentials that risk cracking the glass. Autoclave the flask body open, allow it to cool, then apply the snap cap after sterilization. The flask body itself is fully autoclavable at 121°C, 15 psi for standard 20-minute cycles.How many flasks are in each pack?The 10mL and 25mL sizes come in packs of 6, the 50mL, 100mL, 200mL, and 250mL sizes come in packs of 4, and the 500mL and 1000mL sizes come in packs of 2. Each flask ships with its matching snap cap included. All prices are per pack.Are these flasks interchangeable with Corning Pyrex or Kimax Class A volumetric flasks?Functionally yes for standard analytical applications — all are ASTM E-288 Class A certified borosilicate volumetric flasks with TC calibration at 20°C. The SIBATA 2303A Series uses a snap-cap closure rather than the traditional ground-glass stopper format used by Pyrex and Kimax. If your SOP specifies a ground-glass stopper, use the SIBATA 2306A glass-stopper series instead.Quality AssuranceSIBATA Scientific Technology has manufactured precision analytical glassware since 1932. The 2303A Series Volumetric Flasks are certified to ASTM E-288 Class A specifications and comply with USP glassware standards. Each flask undergoes individual calibration verification before shipment. SIBATA's ISO 9001-certified quality management system governs production and inspection across all volumetric glassware series. Every flask carries a 1-year manufacturer warranty.As an authorized dealer, we ship directly from USA inventory.
