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  V/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  oil >  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  V/V at rupture is important parameter We need  V vs PRESSURE curve for both acrylic vessels

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

5. Divide detector into filling zones Level monitoring to cm accuracy is needed. Consider monitoring curvature of flat acrylic faces 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

6. CONCLUSIONS Acrylic vessels are highly elastic. Need  V/V vs pressure and  V/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)