Name: Round-Bottom Graduated Centrifuge Tube
Brand: RichTech

Specifications

Round-Bottom Graduated Centrifuge Tube · Specifications

The following are standard capacity options with graduation ranges. Custom capacities or special graduation intervals are available upon request.

Request custom specs

Nominal Capacity (mL)	Graduation Range (mL)	Graduation Interval (mL)	Approx. Diameter (mm)	Approx. Height (mm)	Bottom Type	Packaging (pcs/case)	Material
50	5 – 50	2.0	30	100	Round	400	Borosilicate 3.3
100	10 – 100	5.0	36	130	Round	300	Borosilicate 3.3

* Diameter and height are approximate values. Actual dimensions may vary slightly.
* Custom graduation intervals available upon request.
* Non-graduated versions (standard round-bottom tubes) and custom markings also available.

Rotor Compatibility: The 50ml size fits standard 30mm rotor apertures; the 100ml size fits 36mm rotor apertures. Verify rotor compatibility before use. For high-speed or large-volume applications, rubber cushions or adapters are strongly recommended.

Product Description

Round-bottom graduated centrifuge tubes are a versatile upgrade to standard round-bottom tubes, incorporating precise volume graduations directly on the tube body. Manufactured from high-quality borosilicate glass 3.3, the rounded bottom promotes even pellet distribution and facilitates resuspension — particularly valuable for cell washing and bacterial pellet resuspension applications. Available in 50ml and 100ml large-volume capacities, these tubes eliminate sample transfer steps between centrifugation and volume measurement, reducing sample loss and handling errors.

Key Features

Borosilicate Glass 3.3: ISO 3585 compliant · Low thermal expansion · Thermal shock resistance up to 280°C · Resistant to acids, alkalis, and organic solvents
Round-Bottom Design: Even pellet distribution · Facilitates resuspension · Compatible with a wide range of rotors
Precise Volume Graduations: Permanent white enamel markings · Key volume points verified for accuracy
Large-Volume Capacities: Available in 50ml and 100ml — ideal for large-volume sample processing
High Mechanical Strength: Uniform wall thickness · Reliable under standard centrifugation conditions
Superior Clarity: High-purity glass enables clear visualization of pellet formation
Autoclavable: 121°C / 15 psi / 20 minutes steam sterilization
Integrated Design: Centrifugation and quantification in a single vessel — reduces sample transfer

Round vs Conical Bottom: Round-bottom tubes feature a rounded base that promotes even pellet distribution and facilitates resuspension — ideal for cell washing and bacterial pellet resuspension. Conical tubes are better suited for pellet concentration and micro-volume collection. Round-bottom tubes also offer broader rotor compatibility.

Quality Assurance

Each round-bottom graduated centrifuge tube undergoes rigorous dimensional inspection, graduation accuracy verification, and mechanical strength testing. The white enamel markings are permanently fused to the glass surface, remaining legible through repeated washing and autoclaving cycles.

Note: Graduations are intended for rapid estimation. For precise volumetric measurements, use calibrated volumetric flasks or pipettes. Always inspect tubes for cracks or chips before centrifugation, and use appropriate adapters or cushions.

Applications

Typical Application Areas

Biopharmaceutical

Large-volume cell culture pellet collection · Protein precipitation · Vaccine production centrifugation steps

Clinical Diagnostics

Large-volume body fluid (ascites, CSF, etc.) concentration · Sedimentation rate determination

Microbiology

Large-volume fermentation broth cell collection · Cell washing and resuspension (round-bottom design facilitates resuspension)

Environmental Monitoring

Suspended solids collection from large-volume water samples · Sediment quantification

Food Testing

Solid-liquid separation in large-volume sample preparation

Round-Bottom vs Conical Graduated Comparison

Pellet Collection Conical is better for micro-volume pellet concentration; Round is better for even distribution and resuspension
Resuspension Round-bottom design facilitates easier resuspension with less pellet sticking
Rotor Compatibility Round-bottom tubes offer broader compatibility with more rotor types
Capacity Both offer 50ml and 100ml — choose based on your application
Selection Choose round-bottom for resuspension/washing applications; choose conical for pellet concentration

Tip: Round-bottom graduated centrifuge tubes are particularly suitable for cell washing and resuspension applications — the rounded base makes resuspension easier and more complete. For best results, pair with RichTech pipettes and graduated cylinders for a complete sample preparation workflow.

Round-Bottom Graduated Centrifuge Tube Operation Guide

03

Preparation Before Use

Inspect for cracks, chips, or rim damage — damaged tubes must never be used
Verify graduations are clear and legible
Wash with mild detergent and soft brush — rinse 3 times with distilled water
Autoclave at 121°C / 15 psi / 20 minutes
Dry at 60°C or air dry inverted before use

04

Centrifugation Procedure

Counterbalance precisely: Symmetrical placement with weight deviation ≤ 0.1g
Fill volume: Do not exceed 80% of nominal capacity
Rotor matching: Ensure tube fits rotor aperture — use rubber cushions or adapters when necessary
Centrifuge settings: Recommended RCF for glass tubes: ≤ 5,000 × g
Acceleration/Braking: Use medium acceleration/deceleration settings

05

Post-Centrifugation Reading & Handling

Allow tubes to stand for 2–3 minutes before opening
Read volume at the bottom of the meniscus (standard graduated cylinder technique)
Record pre- and post-centrifugation volumes
Resuspension: The round bottom is ideal for resuspension — add resuspension buffer and pipette up and down repeatedly to resuspend the pellet. The rounded design provides no dead corners for more complete resuspension
For supernatant collection, carefully aspirate with a pipette without disturbing the pellet

06

Cleaning & Maintenance

Clean immediately after use to prevent residue adhesion
Routine cleaning: Mild detergent + soft brush — rinse 3 times with distilled water
Stubborn residues: Soak in dilute nitric acid or specialized cleaning solution for 2–4 hours
Avoid strong alkaline cleaners or abrasive brushes that may damage graduations
Air dry inverted or place in oven at 60°C
Store upright in dedicated tube racks

Care & Notes

Show care & notes

Safety Precautions

Always secure caps or seal with Parafilm during centrifugation
When working with biohazardous, corrosive, or highly toxic samples, use a biosafety cabinet or fume hood
Glass centrifuge tubes are not suitable for dry-heat sterilization (above 160°C) — use autoclaving
If unusual vibration or noise occurs during centrifugation, stop immediately and inspect

Do not

Never use cracked or damaged centrifuge tubes
Take volume readings under consistent lighting conditions to avoid parallax error