Swedish Defence Research Agancy (FOI) has, on behalf of the Swedish Fortifications Agency (FortV), performed experiments with air blast against blast valves and subsequent functional control of the airflow through the valves. The purpose of the experiments was to investigate the valves' ability to withstand blast load while maintaining function. The experiments were performed in shock tube IV at Botele Udd in Märsta. Experimental objects for this study have been two types of blast valves: PSV-350 and PV-KK-6. The PSV-350 can withstand what the experiments can find out three blast loads with 2.7 MPa, 15.7 kPas and 53 ms duration. At this load, a blast load with a duration of 3.6 ms is let through the valve before it closes completely. The PV-KK-6 can withstand what the experiments can find out three blast loads with 1.25 MPa, 11.1 kPas and 54 ms duration. At this load, a blast load of approximately 1.7 ms duration is let through the valve before it closes completely.