## Common ground
All are filter plates and discs used in laboratory filtration processes.
## Options at a glance
**3926.90 – Plastic material**
- **Defining trait:** Made from synthetic polymer, often disposable and chemically resistant.
- **Typical examples:** Polypropylene or PTFE membrane filters, syringe filter plates.
- **Best fit when:** Used for low to moderate temperatures, non-corrosive chemicals, or single-use applications.
**6903 – Refractory ceramic**
- ****Defining trait:** High heat and chemical resistance; used in extreme conditions.
- **Typical examples:** Porous ceramic filters for high-temp or aggressive chemical environments.
- **Best fit when:** Applications involving high temperatures (>1000°C) or strong acids/bases.
**6909.1X – Ceramic (general)**
- **Defining trait:** Made from non-refractory ceramic; less heat-resistant than refractory types.
- **Typical examples:** Porous ceramic filter discs for general lab use, e.g., water or air filtration.
- **Best fit when:** Moderate temperature and chemical exposure; reusable in standard lab settings.
**7017 – Glass**
- **Defining trait:** Transparent, highly chemically inert, and heat-resistant.
- **Typical examples:** Glass frits, sintered glass filters for vacuum filtration.
- **Best fit when:** Need visual monitoring of filtration, high purity requirements, or moderate to high heat use.
## Key differences
| Feature | 3926.90 (Plastic) | 6903 (Refractory ceramic) | 6909.1X (Ceramic) | 7017 (Glass) |
|---------------------|-------------------|----------------------------|-------------------|--------------|
| Heat resistance | Low | Very high | Moderate | High |
| Chemical resistance | Good | Excellent | Moderate | Excellent |
| Transparency | Opaque | Opaque | Opaque | Transparent |
| Reusability | Often disposable | Reusable | Reusable | Reusable |
## How to choose
- Is the filter used at high temperatures (>500°C)? → 6903
- Does it need to be transparent for visual monitoring? → 7017
- Is it for single-use or non-corrosive chemicals? → 3926.90
- Is it for general lab use with moderate conditions? → 6909.1X
## Overlaps & pitfalls
- Some ceramic filters (6909.1X) may overlap with refractory types (6903) in heat resistance; priority should be based on actual operating temperature.
- Glass and plastic can both be used for similar applications, but glass is preferred when transparency or chemical purity is critical.
- If the product is reusable and handles strong chemicals, 7017 or 6903 may apply—choose based on heat and corrosion needs.
- No clear priority rule; use the **main function** (e.g., visual monitoring vs. high-temp use) to decide