Propane peak shaving systems operate as follows:

• Liquid is withdrawn from the storage tank and, if required, the pressure is raised via motor-driven pump.
  
  
• The liquid is heated in a vaporizer and converted to a super-heated vapor.
  
  
• Propane vapor is mixed or "blended" with air, producing a "propane-air" mix. The mix is injected into the natural-gas distribution system. The volume of propane-air is normally limited to less than about 50% of the combined natural gas / propane-air stream, keeping the specific gravity of the combined stream at less than 1.00 (Air = 1.00).