Calculating Reaction Force

[commissioning]

When Executing an air blow through a circuit of piping at high volumes and resonable pressures. How would you calculate the reaction force that the piping circuit will generate by the open end exit blow of air? Need a detailed method of how to calculate and what the numbers used represent and mean.

[Studiot]

Reaction force = rate of change of the momentum of the escaping gas.

[commissioning]

I know that but how do I calculate. For example. Pipe area x average blow pressure x 100? I mean how?