Safety cut-off for fluid heating natural gas pre heater - has all energy for operation of device generated by flow medium itself

A safety device for cut off of fluid in or out flow to or from a natural gas pre-heater device, has the energy required for the operation or activation of the safety type device used to regulate or cut off the flow of heat medium generatedly and removed from the fluid medium itself. A further characteristic of this system is that the cut off point for the safety device is defined by the expansion of the operation space of a pressure cylinder. The safety device can thus be operated directly by the flow medium itself and does not required any external powering device or system.