## Common ground
All options are types of drying tubes used for gas drying or moisture removal in laboratory settings.
## Options at a glance
**3926.90 – Plastic**
- **Defining trait:** Made from plastic, typically polyethylene or PTFE, offering chemical resistance and low cost.
- **Typical examples:** Plastic desiccant tubes for general lab use, disposable drying columns.
- **Best fit when:** Chemical compatibility with acids/bases is needed, or low-cost, single-use applications.
**6903 – Refractory ceramic**
- **Defining trait:** Made from high-temperature-resistant ceramic, suitable for extreme heat and harsh environments.
- **Typical examples:** Drying tubes in industrial furnaces, high-temp gas handling systems.
- **Best fit when:** Operating temperatures exceed 800°C or exposure to aggressive thermal/chemical conditions.
**6909.1X – Ceramic**
- **Defining trait:** General ceramic material, less heat-resistant than refractory types; used for moderate conditions.
- **Typical examples:** Lab drying tubes in standard chemical setups, non-thermal applications.
- **Best fit when:** Moderate temperature and chemical exposure; cost-effective alternative to glass.
**7017 – Glass**
- **Defining trait:** Made from borosilicate or soda-lime glass, offering visibility and high purity.
- **Typical examples:** Standard lab drying tubes in distillation setups, analytical instruments.
- **Best fit when:** Visibility of process is essential, or high chemical purity is required.
## Key differences
| Feature | 3926.90 (Plastic) | 6903 (Refractory Ceramic) | 6909.1X (Ceramic) | 7017 (Glass) |
|---------------------|-------------------|----------------------------|--------------------|--------------|
| Heat resistance | Low | Very high | Moderate | Moderate |
| Chemical resistance | High (varies) | Very high | Medium | High |
| Visibility | None | None | None | Yes |
| Typical use | Disposable, lab | Industrial, high-temp | General lab | Precision work |
## How to choose
- Is the tube exposed to high temperatures (>800°C)? → 6903
- Do you need to see inside during operation? → 7017
- Is chemical resistance or low cost most important? → 3926.90
- Is moderate use in standard lab conditions expected? → 6909.1X
## Overlaps & pitfalls
Plastic (3926.90) and ceramic (6909.1X) may both be used in general labs, but plastic is more chemically resistant to acids; ceramic is more durable. Refractory ceramic (6903) is a subset of ceramic—use 6903 only for extreme heat. If the product’s main function is visibility or purity, prioritize glass (7017). No option is clearly dominant—choose based on the **primary function** or **environmental conditions**