Regulator assembly and test method

A method of testing a regulator, comprising:

• introducing a test fluid into a plurality of test regulator assemblies, wherein:
• the test fluid has a molecular weight that is between 80% and 110% of a molecular weight of a selected fluid to be supplied by a fluid supply package, and
• each of the plurality of test regulator assemblies includes a first regulator and a second regulator, the first regulator of each of the plurality of test regulator assemblies having a predetermined outlet pressure;
• monitoring a flow of the test fluid through the second regulator of each of the plurality of test regulator assemblies;
• determining a number of spikes in the monitored flow through the second regulator for each of the plurality of test regulator assemblies;
• and
• assembling a regulator assembly for the fluid supply package, the regulator assembly including the first regulator and the second regulator selected from one of the plurality of test regulator assemblies that exhibited fewer than two spikes in the observed flow.