Abstract: A pressure sensitive valve 10 comprises a valve body 12 defining a bore 14, an inlet port 16 and an outlet port 18. The inlet port 16 is in fluid communication with the outlet port 18 and defines a fluid flow path 20. The fluid flow path 20 is in communication with the bore 14. A reverse buckling member 22 extends at least partially across the bore 14, the member 22 being adapted to reverse its conformation when a set pressure has been exceeded. The valve 10 includes means for actuating inversion of the reverse buckling member 22 when the set pressure has been exceeded. The valve 10 also includes means for sealing the reverse buckling member 22 from the fluid flow path 20.