12 mm Test Tube Stoppers — LDPE, Orange, BD® Compatible | 1000/Bag (300-2912-E20)
These orange LDPE plug-in friction-fit stoppers are designed for standard 12 × 75 mm test tubes with a 12 mm OD, covering the widest range of clinical, microbiology, and research tube formats in a single SKU. Low-density polyethylene's inherent flex modulus allows the stopper plug to compress on insertion and spring back against the tube inner wall, maintaining reliable friction-fit closure across a working temperature range of −20°C to +60°C — from frozen archive through incubation without hardening or losing retention. Supplied non-sterile in 1000/Bag, these stoppers are a cost-effective solution for high-volume tube-capping programs in clinical laboratories, hospitals, and research institutions.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number (MPN) | 300-2912-E20 |
| Tube OD | 12 mm |
| Tube Format | Standard 12 × 75 mm |
| Cap Style | Stopper — plug-in friction fit |
| Material | Low-Density Polyethylene (LDPE) |
| Color | Orange |
| Temperature Range | −20°C to +60°C |
| Sterility | Non-Sterile |
| Pack Size | 1000/Bag |
| BPA / Phthalates | BPA-free; no phthalate plasticizers |
| Country of Origin | USA (California) |
Applications
- Microbiology culture tube capping: LDPE flexibility maintains a reliable seal on TSB, BHI, and LB broth tubes during 37°C incubation without stopper hardening or loss of fit.
- Specimen tube archiving: Prevents evaporation from serum, plasma, and urine specimens during extended refrigerated or frozen storage at temperatures as low as −20°C.
- Clinical chemistry sample handling: Seals 12 mm chemistry tubes pre-analysis; LDPE is chemically inert to serum and plasma matrices, ensuring no leaching into tube contents.
- Cell culture tube capping: Suitable for suspension cell culture and virus propagation tubes where a flexible, repeatable closure is required.
- Pneumatic tube transport: LDPE flex retention keeps stoppers engaged through the acceleration forces of hospital pneumatic transport systems.
- Color-coded batch routing: Orange is widely used in clinical laboratory color-coding conventions to designate STAT or priority specimens, enabling rapid visual identification of urgent tube batches in processing racks without scanning.
Compatibility
These stoppers are designed to fit standard 12 mm OD test tubes, including the 12 × 75 mm format commonly used across BD® and other major tube brands in clinical chemistry, hematology, microbiology, and research workflows. The plug-in friction-fit design accommodates the repeat insertion and removal cycles typical of clinical and research tube programs. Because tube inner-wall tolerances can vary slightly by manufacturer, verify fit against your specific tube lot before deploying across high-volume programs.
Chemical Resistance
| Reagent / Condition | Compatibility |
|---|---|
| Aqueous buffers / saline | Excellent |
| Serum, plasma, whole blood | Excellent |
| Urine | Excellent |
| Broth media (TSB, BHI, LB) | Excellent |
| Dilute acids and bases | Good |
| Ethanol (<70%) | Good — short-term contact |
| Chlorinated solvents (chloroform, DCM) | Not recommended |
| Aromatic solvents (toluene, xylene) | Not recommended |
Quality & Procurement
Made in USA at Caplugs® Evergreen's California facility, these stoppers are manufactured from BPA-free, phthalate-free LDPE resin under ISO 9001 quality management. LabSupplies.com is an authorized Caplugs® Evergreen dealer and ships from USA inventory, typically same business day for stocking items. Tiered volume pricing is available for institutional purchasers, hospital systems, and grant-funded laboratories — contact our procurement team for contract pricing on cases and pallet quantities.
Frequently Asked Questions
Are these stoppers sterile?
No — the 300-2912-E20 is supplied non-sterile in 1000/Bag bulk packaging. For applications requiring a sterile closure, consider gamma-sterilized alternatives or autoclave the stoppers separately, noting that LDPE has a maximum working temperature of +60°C and is not intended for steam autoclaving.
Will these stoppers fit tube formats other than 12 × 75 mm?
The friction-fit plug is sized for a 12 mm OD tube, which is the standard diameter for 12 × 75 mm tubes used across clinical chemistry, microbiology culture, and research workflows. Other lengths using the same 12 mm OD — such as 12 × 100 mm — may also accept this stopper, but fit should be verified against your specific tube lot and wall thickness before full deployment.
Why orange — does the color have a specific meaning in the lab?
Orange is widely used in clinical laboratory color-coding systems to designate STAT or priority specimens. Using orange stoppers on urgent tube batches allows processing staff to identify and route high-priority samples visually, without scanning, which reduces handling time at busy intake stations.
Can these stoppers be used at freezer temperatures for long-term specimen storage?
Yes — LDPE retains its flexibility down to −20°C, so these stoppers maintain friction-fit engagement through freeze-thaw cycles without becoming brittle or losing retention. For storage colder than −20°C (such as −80°C ultralow freezers), verify stopper performance under your specific conditions before committing archived specimens.