Fig. 4
From: In-situ monitoring of 3He/4He in summit gases of Kilauea Volcano (Hawaii) prior to the 2020 eruption
Schematic diagram of the Vent Gas Purification System (VGPS). All components fit within a portable Pelican™ case. Three removable chemical cartridges clamp onto the top layer (level 2) with two DC power supplies and a customized Teflon™ KNF diaphragm roughing pump located below (level 1). Internal Valcor™ Teflon™ solenoid valves direct gas flow; valves 1 (gradient), 3 (by-pass) and 5 (exhaust) are indicated. Pressure is measured with an InstruTec™ Stinger convection gauge. A custom command electronics board relays valve openings, temperatures, pressures and roughing pump on/off via a Rabbit™ microprocessor. A small heater assembly is used for extremely cold environments. The VGPS is also insulated with closed-cell foam. A detailed description of the working procedure for this instrument can be found in the text and in McMurtry et al. (2019a, b)