*** Our Vented cap WILL LEAK. The cap is vented by machining a groove into the threads and below the gasket allowing the gasket to be bypassed. Tanks that are not stationary (Like in the back of a truck) will leak fuel as is sloshes back and forth. We recommend using a NON Vented cap in all situations and utilize a vent port on the tank itself.
What does NPSM Loose Mean? NPSM stands for National Pipe Straight Mechanical. Loose means that we machine these on the higher end of the tolerance to account for Weld distortion to the neck and expansion and contraction throughout the seasons.
