Leakage values

For comparison purposes, aitemate methods of air leakage estimation may be used. Figure 6-21. Maximum air leakage values for commercially tight systems. Reprinted by permission [11]. 

SYSTEM VOLUME-CUBIC FEET MAXIMUM AIR LEAKAGE VALUES FOR COMMERCIALLY TIGHT SYSTEMS... 

The helium leakage value was tested on the half cells in the oxidized state before the coating of cathode. Helium is suitable to be used as the test gas because its molecular is smaller than all the gases under the operation condition of SOFC cells. The helium flowed through the half cell at a pressure difference of 1000 hPa. The shown values in this test were normalised to the measurement area and to a pressure difference of 100 hPa, which was typical for an SOFC stack. One large squared area of 16cm was measured per cell. The leak rate value of samples without polymeric sol-gel layers was around 5-10" (hPa dmV(s cm ). By applying a polymeric sol-gel layer on top of the colloidal-sol-derived intermediate layers, the leak rate value of samples was improved to 1.5-10 (hPa dm ( s cm ). 

The seat leakage ofthe regulator. This is the tendency of the regulator to leak across the seat with the regulator valve closed fully and high pressure upstream of the valve. A low leakage value is preferred. 

Shielding Effect (a) , dB EMI Leakage (%) Value Judgement (technical)... 

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