50 mL Centrifuge Tube Screw Caps — HDPE, Yellow, Falcon®-Compatible | 300-3541-Y20 | 1000/Bag
These yellow HDPE screw caps are designed for Caplugs® Evergreen 50 mL centrifuge tubes, providing a secure threaded closure rated for IATA P650 leak-free transport, −80 °C cryogenic storage, and autoclave sterilization at 121 °C. Supplied non-sterile in 1000/Bag, part number 300-3541-Y20 supports high-throughput clinical, biorepository, and molecular biology workflows where color-coded specimen routing is essential.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number (MPN) | 300-3541-Y20 |
| Cap Type | Screw cap — threaded engagement |
| Material | High-Density Polyethylene (HDPE) |
| Color | Yellow |
| 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
- Sealing high-volume serum, plasma, and urine specimens in 50 mL centrifuge tubes for IATA P650-compliant transport
- Color-coded batch routing using yellow caps to designate large-volume blood culture, SPS-anticoagulated, and ACD specimen sets per CLSI H3 convention
- Biorepository and genomics archiving of 50 mL tubes at −80 °C, where HDPE maintains dimensional stability and thread integrity
- Capped centrifugation for serum/plasma separation — threaded engagement retains the cap through centrifuge forces
- Cell culture harvest and DNA/RNA extraction prep using 50 mL centrifuge tubes, where HDPE is compatible with culture media and standard extraction buffers
- Replacement caps for 50 mL extraction and biobank tubes requiring a secure, re-sealable closure
Compatibility
These caps are engineered for the 50 mL centrifuge tube neck thread used on Caplugs® Evergreen 50 mL tubes, and the thread geometry is also consistent with standard 50 mL conical centrifuge tubes — including Falcon®-style formats widely used across clinical and research labs. It is important to note that the 300-3541 thread is specific to the 50 mL format: it is larger than both the 300-3532 cap family (20/30 mL tubes) and the 300-3010/300-3022 family (15 mL tubes) and is not interchangeable with either. Customers switching from OEM or competitor caps are encouraged to validate thread fit with a sample quantity before placing a bulk order. The full 300-3541 range is available in nine colors — including Natural (300-3541-020), Blue (300-3541-B20), Orange (300-3541-E20), and Green (300-3541-G20) — all sharing the same HDPE thread specification.
Chemical Resistance
| Reagent / Condition | Compatibility |
|---|---|
| Aqueous buffers, saline, PBS | Excellent |
| Serum / plasma / urine | Excellent |
| Dilute acids and bases | Excellent |
| Short-chain alcohols (ethanol, isopropanol) | Good — suitable for short-term contact |
| Cell culture media | Good |
| Chlorinated solvents (chloroform, DCM) | Not recommended |
| Aromatic solvents (toluene, xylene) | Not recommended |
| Autoclave (121 °C / 15 psi) | Compatible |
| Cryogenic storage (−80 °C) | Compatible |
Quality & Procurement
Made in USA (California), these Caplugs® Evergreen caps are produced from BPA-free, phthalate-free HDPE resin under ISO 9001 quality management. IATA P650 compliance confirms the threaded closure meets international standards for leak-free transport of primary liquid specimens. LabSupplies.com is an authorized Caplugs® Evergreen dealer and ships from USA inventory; tiered volume pricing is available for hospitals, reference laboratories, and research institutions managing high-throughput tube programs.
Frequently Asked Questions
Will these caps fit standard Falcon® 50 mL conical centrifuge tubes?
The 300-3541 thread geometry is consistent with standard 50 mL conical tube neck threads, including Falcon®-style formats. Because thread tolerances can vary between manufacturers, we recommend confirming fit with a sample quantity before converting from your current OEM supply.
Can these caps be used at −80 °C for long-term biorepository storage?
Yes. HDPE maintains its structural integrity and thread engagement at ultra-low temperatures down to −80 °C, making these caps suitable for cryogenic biobank and genomics archiving applications.
Are these caps autoclavable?
Yes — HDPE is autoclavable at 121 °C / 15 psi. This allows the caps to be sterilized for use in sterile culture or processing workflows prior to tube assembly.
Why yellow? Is there a standard color convention for 50 mL centrifuge tube caps?
Yellow caps in the 300-3541 range align with the CLSI H3 color convention designating large-volume SPS-anticoagulated and ACD specimen batches in 50 mL tube formats. Using the correct color allows clinical staff to route specimen types visually without relying on label reading alone. Nine colors are available in the 300-3541 family to cover the full range of common clinical routing conventions.