Systems, components, and methods for low pressure delivery of plural component systems such as polyurethane foams from unpressurized supply sources

Various examples are provided related to low pressure delivery, e.g., less than 250 psi at the point of application, of plural component system from unpressurized parts A and B material supplies. In one example, a system includes a polyurethane spray foam ("SPF") raw material supply including parts A and B and a fluid handling system that can deliver the SPF raw material at low pressure to a metal spray gun in metered amounts through separate material fluid paths/conduits via a heated hose length and a whip hose. The fluid handling system can also deliver air at low pressure to the spray gun through separate air stream paths so that the air is communicated to the part A and B material conduits forward of the part A and B material input locations, where they are supplied separately to a mixing nozzle that is engaged at an end of the spray gun.