Protectoseal Series No. 16240 Vacuum Relief Vents are intended for use where only vacuum relief is required. They are designed to be side mounted to the tank structure or piping. A pallet in the vent housing retards air intake as the tank normally breathes in due to atmospheric temperature changes or emptying of the tank. The pallet opens and closes to permit only that intake relief necessary to avoid tank damage under normal operating conditions. Series No. 6240 is offered for end-of-line applications.