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AD tank filling & design issues

AD tank filling & design issues. Liquid densities must be tightly controlled Feedback loops between liquid columns and pumps ˛ need column heights Overfill to rupture is possible Purge gas pressures must be equalized. AD Hydrostatics.

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AD tank filling & design issues

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  1. AD tank filling & design issues • Liquid densities must be tightly controlled • Feedback loops between liquid columns and pumps ˛ need column heights • Overfill to rupture is possible • Purge gas pressures must be equalized

  2. AD Hydrostatics • Each acrylic vessel is an enormous hydraulic cylinder acting on itself • The overflow columns function as hydraulic pistons • The acrylic vessels are elastic with a non-linear DV/V vs pressure. Overflow column heights are a balance between a) stiffness of acrylic c) column diameters b) liquid density difference d) mass pumped into detector

  3. Let r oil > r scintillator • Deflection of acrylic until forces balance • 450 kg force for every 1% density difference between scintillator and oil • Column height difference of 4cm for each 1% density difference • Diameter of overflow column is critical We need DV vs PRESSURE curve for both acrylic vessels DV/V at rupture is important parameter

  4. Acrylic vessels appear “stiffer” for small diameter overflow columns and “softer” for large diameter columns Same DV Conversely, filling an overflow column to a preconceived height is dangerous

  5. Divide detector into filling zones • Zone A: oil only • Zone B 106 kg force on acrylic bottom for each cm of height mismatch • Zone C: center vessel filled at constant rate while regulating other two flow rates • Zone D/E: overfill to breaking point possible even with a small difference in column height Level monitoring to cm accuracy is needed. Consider monitoring curvature of flat acrylic faces

  6. CONCLUSIONS • Acrylic vessels are highly elastic. Need DV/V vs pressure and DV/V at failure • Accurate liquid densities needed now---can have major impact on acrylic design • Want LARGE diameter oil overflow and SMALL diameter scintillator overflow • Flexing of acrylic tanks is desirable if filling to pre-specified mass • Rupture of acrylic during filling is possible • Regulation of heights during fill (and drain!) • N2 purging system pressures are critical (±10 mbar)

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