Measurement of gas yields and flow rates using a custom flowmeter

A simple gas collection apparatus based on the principles of a Torricelli tube has been designed and built to measure gas volume yields and flow rates. This instrument is routinely used to monitor and collect methane gas released during methane hydrate dissociation experiments. It is easily and inexpensively built, operates at ambient pressures and temperatures, and measures gas volumes of up to 7 L to a precision of about 15 ml (about 0.0025 mol). It is capable of measuring gas flow rates varying from more than 10(3) to less than 10(-1) ml/min during gas evolution events that span minutes to several days. We have obtained a highly reproducible hydrate number of n=5.891 with a propagated uncertainty of +/-0.020 for synthetic methane hydrate. (C) 2001 American Institute of Physics.