text: * Due to the structure, the pressure difference is theoretically limited to atmospheric pressure (1 bar), and in practice somewhat lower.
  * Besides the drum, other accessories, for example, agitators and vacuum pump, vacuum receivers, slurry pumps are required.
  * The discharge cake contains residual moisture.
  * The cake tends to crack due to their air drawn through by the vacuum system, so that washing and drying are not efficient. 
  * High energy consumption by the vacuum pump.