Parr offers a variety of accessories for its line of pressure reaction vessels to enable the investigator to accurately determine the amount of gas consumed in a reaction conducted at elevated pressures and temperatures. There are essentially two methods used to measure the amount of gas delivered to a reaction vessel. These are:
1. The measurement of the pressure drop in an auxiliary supply vessel of known volume.
2. The measurement and integration of the flow rates using an electronic mass flow meter.
Each of these methods has its advantages and limitations as discussed in the following sections.