1. Balanced tank method Filling scintillator to  M/M ≈10 -4

2. Filling requirements Three liquids simultaneously Level control during filling Total mass to few x10 -3 (~20 kg) Paired mass to few x10 -4 (~2 kg) Stable against a) power interruptions b) bubbles Redundant measurement

3. 1. Fill two 5 ton tanks to specified weight using equalization lines and LOAD CELLS. 2. Pump into detectors 3. Refill & pump to opposite detector 4. Total of four fills EQUALIZATION LOAD CELLS CORIOLIS FLOW METERS

4. Advantages of method Primary reliance on WEIGHT Load cells commercially available (class C3 1x10 -4 ) Filling errors cancel to 10 -5 level

5. Paired mass vs total mass Balanced tanks matched to only 2% Load cell repeatability & drift become second order Flow meters are backup Must prime & drain lines and pumps AD acrylic tanks matched to within 10-20% of  V/V at rupture Load cell & flow meter repeatability & drift are first order errors Must prime & drain lines and pumps Load cell calibration service is available Paired accuracy Total mass accuracy

6. Possible balanced tank arrangement Low pressure & equalization Pumps & flow Dry N2 purge gas Switch yard Load cells