I have an air leak somewhere in a coil or 20 feet of pipe in a mechanical room next to a transformer. I have 160 psi of air on the system and it dropped 30 psi in two days. I have tried to find the lead with 60 psi of water currently but no success. I do not want to put a lot of water pressure on the system and have the leak show itself in a marvelous fashion and ruin the transformer. My question is: How can I calculate how much water pressure is needed to identify the air leak at 130 psi of air? I know the viscosity information and the surface tension for water and the viscosity for air but I have no idea on how to apply them to an equation. I have zero success finding anything online about this, so any help would be greatly appreciated. Thank you.