Stirred-tank internals: in a standard baffled tank bioreactor, what is the typical width of baffles relative to the tank diameter?

Introduction / Context:
Baffles suppress swirling and improve mixing and gas dispersion in stirred tanks. Their geometry—especially width relative to vessel diameter—has strong effects on power draw and flow pattern. This item asks for the standard design range.

Given Data / Assumptions:

• Four radial baffles uniformly spaced are assumed.
• Impeller type and clearance are within common practice.
• Goal is to avoid vortex formation and increase turbulence.

Concept / Approach:
Classic design guidelines recommend baffle width around 0.1*D (roughly 1/10 of the tank diameter). Some specifications accept down to about 1/12 depending on viscosity and foaming behavior. Wider baffles (e.g., 1/3*D) overly restrict flow; much narrower baffles permit vortexing.

Step-by-Step Solution:
1) Start from the rule-of-thumb: baffle width ≈ 0.1*D.2) Convert to fractional range: approximately 1/10 to 1/12 of D.3) Select the option that captures this accepted range.

Verification / Alternative check:
Chemical engineering design texts and vendor datasheets list 0.08–0.12*D as common baffle sizing to mitigate vortex and improve mixing.

Why Other Options Are Wrong:
1/3–1/4 D is excessively wide; 1/15–1/25 D is too narrow; 1/2 D is unrealistic.

Common Pitfalls:
Ignoring that viscous or non-Newtonian media may need modified internals; the stated range is the baseline for general service.

Final Answer:
Between 1/10 and 1/12 of the tank diameter