In chemical, pharmaceutical, and food industries, the tank bottom valve is a critical component for ensuring smooth production flow. Based on the movement direction of the disc, the two most common designs are Rising Disc and Lowering Disc valves. This article explores their differences and applications.
1. Structure and Working Principle
Rising Disc Valve (Put-up)
- Movement: The valve disc rises inward into the reactor vessel to open.
- Key Feature: Known as the “crust-breaking” design. As the disc rises, it physically breaks through any material cakes, sediment, or solidified solids at the bottom of the tank.
- Best For: Applications where materials tend to settle or crystallize during the reaction.
Lowering Disc Valve (Put-down)
- Movement: The valve disc lowers outward (away from the vessel) into the body to open.
- Key Feature: The disc does not occupy any internal space within the reactor. This ensures zero interference with the agitator’s rotation.
- Best For: High-speed mixing or low-clearance agitation systems.
2. Key Differences at a Glance
| Feature | Rising Disc (Put-up) | Lowering Disc (Put-down) |
| Space Utilization | Occupies space inside the vessel | Occupies space inside the valve body |
| Material Handling | Ideal for caking or viscous materials | Ideal for free-flowing liquids/slurries |
| Agitator Gap | Requires a larger bottom clearance | Compatible with ultra-low agitators |
| Sealing Logic | Pressure-assisted sealing (inward) | Actuator-driven sealing (outward) |
| Installation | Standard boss flange (D3) | Typically requires a larger flange (D3) |
3. How to Choose the Right Valve?
Choose a Rising Disc (Put-up) Valve if:
- Your material tends to sediment or form a “crust” during the synthesis process.
- There is sufficient safety clearance between the tank bottom and the agitator blade (clearance must exceed the valve stroke).
- You want to leverage the internal vessel pressure to assist in tight valve sealing.
- Typical Scenario: API synthesis where crystallization occurs at the end of the batch.
Choose a Lowering Disc (Put-down) Valve if:
- Your agitator (e.g., anchor, scraper, or frame type) is positioned very close to the bottom for maximum mixing efficiency.
- The material is free-flowing and does not require physical “breaking” to discharge.
- You prioritize the smallest possible footprint within the vessel to maximize volume.
- Typical Scenario: High-viscosity mixing where the scraper must clear the entire tank bottom.
4. Conclusion
Whether you require a Rising or Lowering design, the ultimate goal is “Dead-Space-Free Discharge.” The Rising Disc valve is your best tool for handling tough sediments, while the Lowering Disc valve is the perfect partner for compact, high-efficiency agitation systems.
At VANVEO, we provide a wide range of GMP-standard Bottom Valves with 20KV spark-tested glass lining or stainless steel cladding, ensuring your process remains safe, clean, and efficient.
