How to Test for Leaks in a Compressed Gas System

The first leak to check is within the regulator To see if there is gas leakage past the diaphragm, rotate the pressure adjusting valve CCW until it is fully open, then slowly open the main tank valve. If any gas leaves the regulator, the regulator is defective or broken and needs repair or replacement. 

To see if you have a leak within the line of your pressure system, close all normal outlets. Then, after opening the main tank valve and rotating the pressure adjusting valve (V-2 see Fig. 5.4) to the desired pressure, turn the main tank valve 

If you know you have a leak but are not sure of the location, do not use a flame to aid your search. If the gas is flammable, the dangers are obvious, but otherwise there is concern of burning parts and equipment. The best and safest technique is to spray, squirt, or drip a soapy water solution on the suspected area. Use either a diluted liquid dish soap or a commercial solution such as Snoop . The evidence of bubbles is a sure sign of a leak. However, be sure you witness bubble formation as opposed to bubbles just sitting there, which are likely to have formed during the application of the bubble solution. 

---