Understanding Dead Volume for a static mixer can be a little tricky. Variables include type of element, qty of elements with the sanitary static mixer and the connection ends. In sanitary tubing systems (e.g., Tri-Clamp fittings used in pharmaceutical, food, or biotech applications), dead volume typically refers to the residual volume of fluid that remains trapped or stagnant in the system after draining or flushing.
This is critical for minimizing contamination risks during cleaning (CIP/SIP) or product changeovers. For a straight tube segment, dead volume is essentially the full internal volume, as there’s no easy drainage path. The helical mixer inside the tube is a static mixing element (e.g., alternating right- and left-hand helices) designed for low shear and high-viscosity blending. Based on ProMixUSA product designs, these mixers have an open geometric structure with no intentional dead spots—fluid flows continuously through the helical channels, promoting full drainage. Thus, the dead volume is effectively the total internal hold-up volume of the assembly, with negligible additional trapping due to the mixer’s design.
Key Specifications
- Tube Size: 1/2″ OD sanitary tubing (standard wall thickness ≈ 0.035 inches).
- Internal Diameter (ID): ≈ 0.430 inches (≈ 10.92 mm), yielding a cross-sectional area of ≈ 0.145 in².
- Length: 6 inches (Adjusted to the Customers Requirement)
- Mixer Impact: The helical elements occupy space but maintain open flow paths (typical void fraction > 90% for helical static mixers), so volume reduction is minimal (< 5–10%). For precision, we approximate as the full tube volume.
CalculationThe internal volume ( V ) is calculated as:
V=π×(ID2)2×LV = \pi \times \left(\frac{ID}{2}\right)^2 \times LV = \pi \times \left(\frac{ID}{2}\right)^2 \times L
where
ID=0.430ID = 0.430ID = 0.430 inches
and
L=6L = 6L = 6 inches.
- Radius: r=0.430/2=0.215r = 0.430 / 2 = 0.215r = 0.430 / 2 = 0.215 inches.
- r2=0.046225r^2 = 0.046225r^2 = 0.046225 in².
- π×r2≈3.1416×0.046225≈0.1452\pi \times r^2 \approx 3.1416 \times 0.046225 \approx 0.1452\pi \times r^2 \approx 3.1416 \times 0.046225 \approx 0.1452 in² (cross-sectional area).
- V=0.1452×6≈0.871V = 0.1452 \times 6 \approx 0.871V = 0.1452 \times 6 \approx 0.871 in³.
Conversions:
- ≈ 0.0040 US gallons.
- ≈ 0.0143 US fluid ounces.
- ≈ 0.423 mL (most relevant for lab/pharma contexts).
The dead volume is approximately 0.87 cubic inches (or 0.42 mL). If the helical mixer significantly occupies space (e.g., >10% void reduction) or if fittings add volume, this could be slightly lower—consult the specific mixer datasheet of ProMixUSA for exact hold-up data.