sentences:  To achieve steady flow, the pump system consists of
  two pump chambers such that each one supplies fuel for half of 
  each cycle.The pump is powered by pressurized gas which acts 
  directly on the fluid.For each half of the pump system, a chamber is 
  filled from the main tank under low pressure and at a high flow 
  rate, then the chamber is pressurized, and then the fluid is 
  delivered to the engine at a moderate flow rate under high 
  pressure.