Abstract: The filter cartridge assembly has a valve body having an interior flow passage, a filter across the interior flow passage, and a check valve assembly in the valve body. The filter removes particulates as small as 0.003 microns. A check valve element adjacent to a valve seat in the interior flow passage has a check valve poppet and a stem. The check valve poppet has a relatively narrow neck, and the check valve poppet is tapered inwardly from the outlet end toward the neck at an oblique angle relative to the longitudinal axis of the valve body that is substantially equal to the oblique angle of the annular valve seat.

Abstract: A triaxial thermopile array geothermal heat flow sensor is designed to measure heat flow in three dimensions in a reconstituted or unperturbed subsurface regime. Heat flow can be measured in conductive or permeable convective media. The sensor may be encased in protective pvc tubing and includes a plurality of thermistors and an array of heat flow transducers arranged in a vertical string. The transducers produce voltage proportional to heat flux along the subsurface regime and permit direct measurement of heat flow in the subsurface regime. The presence of the thermistor array permits a comparison to be made between the heat flow estimates obtained from the transducers and heat flow calculated using temperature differences and Fourier's Law. The device is extremely sensitive with an accuracy of less than 0.1 Heat Flow Units (HFU) and may be used for long term readings.