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
| Specification | Value |
|---|---|
| Part Number (MPN) | 300-3532-DG20 |
| Cap Type | Screw cap — threaded engagement |
| Material | High-Density Polyethylene (HDPE) |
| Color | Dark Green |
| Tube Compatibility | Caplugs® Evergreen 20 mL screw-neck vials; 30 mL centrifuge tubes |
| Thread Note | Larger thread specification than 300-3010 / 300-3022 (15 mL cap family) |
| IATA P650 Compliance | Yes — leak-free primary container seal |
| Cryogenic Storage | Compatible to -20°C and -80°C |
| Autoclave Compatibility | 121°C / 15 psi |
| Sterility | Non-Sterile |
| BPA / Phthalates | BPA-free; no phthalate plasticizers |
| Pack Size | 1000/Bag |
| Country of Origin | USA (California) |
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
| Reagent / Condition | Compatibility |
|---|---|
| Aqueous buffers / saline | Excellent |
| Dilute acids and bases | Excellent |
| Short-chain alcohols (ethanol, isopropanol) | Good — suitable for working concentrations |
| DMSO (working concentrations) | Good — suitable for working concentrations |
| Chlorinated solvents (chloroform, DCM) | Not recommended |
| Aromatic solvents (toluene, xylene) | Not recommended |
| Cryogenic storage (to -80°C) | Compatible — no thread deformation |
| Autoclave (121°C / 15 psi) | Compatible |
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.
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.
