A system and a method of providing PUR/PIR foam using flammable blowing agent. The flammable blowing agent is introduced to PUR/PIR manufacturing equipment via an independent feed-line. This enables a flammable blowing agent storage vessel to be located off site from the foam manufacturing equipment. The independent flammable blowing agent feed-line couples the off-site flammable blowing agent storage vessel with the foam production system. The preferred flammable blowing agent is pentane.