A bottom discharge is designed to be fitted at the bottom of a tank or tanker to ensure loading and unloading. It generally consists of a footvalve, followed by a second closure valve (a ball valve or butterfly valve), and lastly an outlet nozzle with cap or a coupling. The footvalve can have an internal or external spring. Perolo offers both mechanic and pneumatic actuated footvalves. For ISO tank containers, footvalves have an angle of 45° or 30°, whereas with Road Tankers or Offshore tanks an angle of 90° is more common.