50 mL Centrifuge Tube Screw Caps — HDPE, Red, Falcon® Compatible | 1000/Bag (300-3541-R20)
These red high-density polyethylene screw caps are designed for Caplugs® Evergreen 50 mL centrifuge tubes, providing a leak-free threaded closure rated to IATA P650 standards for compliant specimen transport. Supplied non-sterile in 1000/Bag bulk packaging, part number 300-3541-R20 is engineered for the full range of large-volume clinical, biorepository, and molecular workflows that rely on secure, color-coded tube management. The red color mirrors the widely recognized CLSI H3 red-top serum/no-additive convention, making it immediately legible to clinical staff without additional labeling.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number (MPN) | 300-3541-R20 |
| Cap Type | Screw cap — threaded engagement |
| Material | High-Density Polyethylene (HDPE) |
| Color | Red |
| Tube Compatibility | Caplugs® Evergreen 50 mL centrifuge tubes |
| Thread Note | 50 mL thread — 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
- Large-volume specimen sealing: Secure, IATA P650-compliant closure for high-volume serum, plasma, and urine in 50 mL tubes destined for transport or archiving
- Clinical chemistry & immunoassay: Red color designation aligns with the CLSI H3 serum/no-additive convention for immediate tube identification in clinical routing workflows
- Biorepository & serum banking: HDPE maintains dimensional stability and seal integrity at −80°C ultra-low temperature storage
- Centrifugation: Threaded engagement retains the cap securely through centrifuge forces during serum and plasma separation spins
- Cell culture harvest: HDPE is compatible with standard culture media formulations in 50 mL harvest tubes
- High-volume nucleic acid extraction: Replacement caps for 50 mL extraction tubes used in DNA/RNA isolation and genomics banking workflows
- Color-coded batch routing: Nine colors across the 300-3541 family support visual differentiation of specimen type or processing batch without additional labeling
Compatibility
These caps are designed to fit Caplugs® Evergreen 50 mL centrifuge tubes and are dimensionally equivalent to standard 50 mL screw-cap centrifuge tube closures, making them suitable as replacement caps for Falcon® and similarly threaded 50 mL centrifuge tubes. The 300-3541 thread specification is specific to the 50 mL format and is not interchangeable with the 300-3532 cap family (20/30 mL tubes) or the 300-3010/300-3022 cap family (15 mL tubes). Validate cap-to-tube thread fit with a sample quantity before committing to bulk purchase, particularly when replacing caps on tubes from a third-party manufacturer.
Chemical Resistance
| Reagent / Condition | Compatibility |
|---|---|
| Aqueous buffers, saline, serum, plasma | Excellent |
| Dilute acids and bases | Excellent |
| Short-chain alcohols (brief contact) | Good — short-term exposure |
| Aromatic solvents (benzene, toluene) | Not recommended |
| Chlorinated solvents (chloroform, DCM) | Not recommended |
| Autoclave (121°C / 15 psi) | Compatible |
| Cryogenic storage (−80°C) | Compatible |
Quality & Procurement
Made in USA at Caplugs® Evergreen's California manufacturing facility, these caps are produced from BPA-free, phthalate-free HDPE resin under ISO 9001 quality management. IATA P650 compliance supports their use as primary container closures in regulated specimen transport programs. LabSupplies.com is an authorized Caplugs® Evergreen dealer, shipping from USA inventory with tiered volume pricing available for clinical labs, hospitals, biobanks, and grant-funded research institutions.
Frequently Asked Questions
Will these caps fit my existing 50 mL Falcon® tubes?
The 300-3541-R20 caps share the standard 50 mL centrifuge tube thread geometry used by Falcon® and most major brands in the 50 mL format. Because thread tolerances can vary slightly between manufacturers, we recommend testing a sample lot against your specific tubes before placing a bulk order.
Can these caps be autoclaved, and are they safe for −80°C freezer storage?
Yes to both. HDPE maintains its dimensional integrity through autoclave cycles at 121°C / 15 psi and remains stable at ultra-low temperatures down to −80°C, making these caps appropriate for biorepository and cryo-archiving applications.
Are these the same thread size as the 15 mL or 20/30 mL Caplugs® Evergreen caps?
No. The 300-3541 thread is specific to the 50 mL format and is larger than both the 300-3010/300-3022 family (15 mL) and the 300-3532 family (20/30 mL). These three cap families are not interchangeable, so confirm your tube format before ordering.
Is the red color clinically significant, or purely cosmetic?
Red is the color convention established by CLSI H3 for serum/no-additive tubes, the most widely recognized clinical tube color convention. Using red caps on 50 mL serum aliquot or banking tubes allows clinical and biobank staff to identify specimen type by color immediately, reducing sorting errors in high-throughput workflows.