Dear Boyu,Joshi,

Please see the revised drawing of Bottom Tank for  ATFE-Ib and ATFE-II  REV-4 Model (1). The angle is kept 45 deg because if we make it to 60 deg, the holdup volume will increase significantly.
The level switch will be float type. It might trap the viscous liquid. Our question to Mr. Joshi: Should we use a vibration fork type level switch instead? 
Please approve the drawing if you do not have any other doubts.

Regards,

Atul
