50 mL Centrifuge Tube Screw Caps — HDPE, Green, Falcon® Compatible, 1000/Bag (300-3541-G20)
These green High-Density Polyethylene (HDPE) screw caps are designed for Caplugs® Evergreen 50 mL centrifuge tubes, supplied non-sterile in a convenient 1000/Bag pack for high-volume clinical, research, and biorepository workflows. The threaded engagement provides a leak-free primary container seal that meets IATA P650 transport requirements, and the green color enables immediate visual differentiation of specimen types, processing batches, or collection-site categories across centrifuge racks and processing areas. HDPE construction delivers reliable performance from -80°C ultra-low temperature storage through autoclave sterilization at 121°C.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number (MPN) | 300-3541-G20 |
| Cap Type | Screw cap — threaded engagement |
| Material | High-Density Polyethylene (HDPE) |
| Color | Green |
| Tube Compatibility | Caplugs® Evergreen 50 mL centrifuge tubes |
| Thread Note | 50 mL format only — larger than 300-3532 (20/30 mL) and 300-3010/300-3022 (15 mL) families; not interchangeable |
| IATA P650 | Compliant — leak-free primary container seal |
| Cryogenic Storage | Compatible to -80°C |
| Autoclave Compatibility | 121°C / 15 psi |
| Sterility | Non-Sterile |
| Pack Size | 1000/Bag |
| BPA / Phthalates | BPA-free; no phthalate plasticizers |
| Country of Origin | USA (California) |
Applications
- Color-coded specimen routing — green caps visually distinguish specific specimen categories, processing rounds, or collection-site types from other tube batches in shared centrifuge racks
- Large-volume serum, plasma, and urine collection and transport with IATA P650 compliant leak-free closure
- Biorepository and biobank archiving of 50 mL tubes at -80°C ultra-low temperature storage
- Capped centrifugation for sample separation — threaded engagement retains the cap through centrifuge forces
- Cell culture harvest in 50 mL centrifuge tubes with HDPE compatibility across common culture media formulations
- High-volume DNA/RNA extraction prep and genomics banking using 50 mL nucleic acid extraction tubes
- Replacement caps for existing 50 mL Caplugs® Evergreen tube programs
Compatibility
These caps are engineered for the Caplugs® Evergreen 50 mL centrifuge tube format and are compatible with Falcon®-style 50 mL centrifuge tubes sharing the same neck thread geometry. The 300-3541 thread is specific to the 50 mL format and is larger than both the 300-3532 cap family (20/30 mL tubes) and the 300-3010/300-3022 cap family (15 mL tubes) — these cap families are not interchangeable. Customers switching from OEM or alternate-brand 50 mL tube caps should validate fit with a sample quantity before committing to bulk purchase. The green cap (300-3541-G20) is one of nine colors available in the 300-3541 range, all sharing identical HDPE thread specification; other available colors include Natural (300-3541-020), Blue (300-3541-B20), Orange (300-3541-E20), and Lavender (300-3541-L20).
Chemical Resistance
| Reagent / Condition | Compatibility |
|---|---|
| Aqueous buffers / saline | Excellent |
| Serum / plasma / urine | Excellent |
| Dilute acids and bases | Good |
| Ethanol and common alcohols | Good — short-term contact |
| Culture media formulations | Good |
| Chlorinated solvents (e.g., chloroform) | Not recommended |
| Aromatic solvents (e.g., toluene, xylene) | Not recommended |
| Cryogenic storage (to -80°C) | Compatible |
| Autoclave (121°C / 15 psi) | Compatible |
Quality & Procurement
Made in USA at Caplugs® Evergreen's California manufacturing facility, these screw caps are produced from BPA-free, phthalate-free HDPE resin under ISO 9001 quality management. The 300-3541-G20 is compliant with IATA P650 requirements for leak-free primary container transport closures, providing confidence for both domestic and international specimen shipment programs. LabSupplies.com is an authorized Caplugs® Evergreen dealer, shipping from USA inventory with tiered volume pricing available for hospitals, clinical reference laboratories, biotech companies, and research institutions placing recurring or high-volume orders.
Frequently Asked Questions
Will these caps fit Falcon® 50 mL centrifuge tubes?
These caps are compatible with Falcon®-style 50 mL centrifuge tubes that share the standard 50 mL neck thread geometry. Because thread tolerances can vary slightly between manufacturers, we recommend validating fit with a sample quantity before a full bulk purchase.
Can these caps be autoclaved?
Yes — HDPE is autoclavable at 121°C / 15 psi, making these caps suitable for workflows that require sterilization of capped tubes or caps alone before use.
Are these caps compatible with -80°C freezer storage?
Yes — HDPE maintains structural integrity and thread seal integrity down to -80°C, making these caps appropriate for biorepository and biobank archiving in ultra-low temperature freezers.
Why are there nine cap colors in the 300-3541 range, and do they all fit the same tubes?
All nine colors in the 300-3541 family are produced from the same HDPE thread specification and fit the same Caplugs® Evergreen 50 mL centrifuge tube format. The color range exists specifically to support color-coded specimen management programs, allowing labs to visually separate specimen types, processing batches, or collection sites without any additional labeling step.