20 mL Centrifuge Tubes, Screw Caps, HDPE, Dark Green — 300-3532-DG20 | 1000/Bag | Caplugs® Evergreen

20 mL Vial & 30 mL Centrifuge Tube Screw Caps — HDPE, Dark Green, 1000/Bag (300-3532-DG20)

These dark green High-Density Polyethylene screw caps are designed to close Caplugs® Evergreen 20 mL screw-neck vials and 30 mL centrifuge tubes, providing an IATA P650 compliant leak-free seal for biological specimen transport. The 300-3532-DG20 uses a larger thread specification than the 15 mL cap family (300-3010 / 300-3022), sized specifically for the wider neck of 20 mL and 30 mL tube formats. Supplied non-sterile at 1000 caps per bag, these caps support cold-chain storage down to -80°C and are autoclave compatible at 121°C.

Technical Specifications

Applications

• Capping 20 mL screw-neck vials for large-volume specimen collection and storage
• Sealing 30 mL centrifuge tubes during serum and plasma separation workflows
• Leak-free closure for courier and air transport of serum, plasma, and urine in large-format tubes (IATA P650)
• Ultra-low temperature biorepository archiving of 20 mL and 30 mL format tubes at -20°C and -80°C
• Pre-sterilized cap supply for cell culture and pathogen programs requiring autoclave-compatible closures
• Color-coded batch routing and specimen-type differentiation — the distinct dark green color visually separates these tubes from lighter green variants without requiring secondary labels
• Environmental and field sample collection workflows where a visually unique cap color identifies sample set or processing batch

Compatibility

These caps are sized for the wider neck of Caplugs® Evergreen 20 mL screw-neck vials and 30 mL centrifuge tubes. The thread specification is intentionally larger than that of the 300-3010 plain cap and 300-3022 sprocket cap used on 15 mL tubes, so the two families are not interchangeable. Before placing a bulk order, validate thread fit against your specific tube format — particularly if your lab uses multiple tube sizes from the 300-series range.

Chemical Resistance

Quality & Procurement

Made in USA at Caplugs® Evergreen's California facility, these caps are manufactured from BPA-free, phthalate-free HDPE resin. The IATA P650 compliant thread design has been validated for leak-free transport of biological specimens in primary containers. LabSupplies.com is an authorized Caplugs® Evergreen dealer and ships from USA inventory, typically same business day for stocking items, with volume pricing available for hospitals, biorepositories, and clinical reference laboratories procuring at scale.

Frequently Asked Questions

Will these caps fit my existing 15 mL centrifuge tubes?
No — the 300-3532-DG20 uses a larger thread specification designed for 20 mL vials and 30 mL centrifuge tubes. The 15 mL tube family uses the 300-3010 or 300-3022 caps, which have a smaller thread diameter. Mixing cap families will result in a poor or non-existent seal.

Are these caps safe for ultra-low temperature freezer storage?
Yes. The HDPE material retains dimensional stability and thread engagement through repeated freeze-thaw cycling at both -20°C and -80°C, making these caps suitable for long-term biorepository archiving programs.

Can I autoclave these caps before use in sterile cell culture or pathogen work?
Yes — the caps are autoclave compatible at 121°C / 15 psi. They are supplied non-sterile, so autoclaving prior to use is the recommended approach when a sterile closure is required.

Why choose dark green rather than standard green caps?
Dark green provides a visually distinct color from lighter green variants within a color-coding system, allowing labs to designate specific tube types, processing batches, or environmental sample sets by cap color alone — reducing reliance on secondary labels and minimizing sorting errors in high-throughput workflows.