The cold junction temperature of the channels on a multi-channel terminal block are accurately determined for each terminal pair without affixing a thermistor to each terminal. One embodiment provides accurate cold junction measurement of a six channel device (12 terminals) by mounting or directly affixing only three sensors (e.g., thermistors). The present technique decreases cost by reducing the number of sensors to less than the number of channels or terminals, while providing for accurate co...

A temperature probe assembly for reading heat gradients occurring in internal combustion engines or other components. The assembly has a plurality of separate thermocouples each having an inner junction mounted in an associated heat contact ring. These rings are mounted in spaced relationship on a tip of a cylindrical probe member to provide axially spaced and multiple heat pick-up points when the tip is mounted in a test bore in the cylinder head near the combustion chamber. Leads from the ther...

The apparatus which is located separately from the RTD includes means for measuring the resistance of a plurality of RTDs present at a selected site, the RTDs being those of a number of different RTD types. The module includes means for storing the resistance/temperature map for each of the plurality of RTDs and for determining the temperatures associated with said resistances from the resistance/temperature maps. The resulting plurality of temperatures for each RTD, respectively, is then transm...

A plug-type heat flux gauge can simultaneously measure heat flux on two opposite surfaces of thick or very thin convection or impingement cooled metal walls. The gauge is capable of continuously measuring transient and steady heat flux under transient and steady state gauge temperature operating conditions. The length of the gauge extends through the entire thickness of the material. A non-linear temperature gradient through the gauge can be measured by attaching 3-5 thermocouples along the leng...

A surface controlled subsurface safety valve is positioned in a well production tubing and an adjustable choke is installed in the surface production tubing. The safety valve is operated by the absolute pressure of the production fluids in the well tubing. The adjustable choke is controlled by a timer which periodically cycles the choke to reduce the flow area available for production of well fluids for a predetermined short period of time. The reduction in flow area causes a corresponding build...

A temperature monitoring device for measuring the temperature at a surface of a body, composed of: at least one first thermocouple and a second thermocouple; support members supporting the thermocouples for placing the first thermocouple in contact with the body surface and for maintaining the second thermocouple at a defined spacing from the body surface; and a calculating circuit connected to the thermocouples for receiving individual signals each representative of the temperature reading prod...

A downhole tool (34) comprising a housing (60), a mandrel (76) slidably disposed within the housing (60), the mandrel (76) having a fluid passageway (52) extending axially therethrough, a valve (50) disposed within the mandrel (76), the valve (50) having first and second positions to selectively permit and prevent fluid flow through the fluid passageway (52) of the mandrel (76) and first and second pistons (98, 104) slidably disposed between the housing (60) and the mandrel (76), the first and s...

A pack-off system for packing off an area of interest in a wellbore, the pack-off system comprising a body, two spaced-apart selectively settable packing elements on the body for sealing off the area of interest, selectively actuatable setting apparatus connected to the body for selectively setting the two spaced-apart selectively settable packing elements, the selectively actuatable setting apparatus actuatable by fluid under pressure introduced into the pack-off system. A method for packing of...

The invention is an assembly which is run into the wellbore to straddle pre-existing control line connections used normally for actuation of a sleeve for a single subsurface safety valve. The lower flapper is closed through the use of one of the control lines. It is then tested against formation pressure to make sure that it holds. Upon determination that the lower flapper is holding, the upper flapper is shut off using the other control line. By adding additional pressure to the control line fo...

The present invention is directed to a system for controlling a hydraulic actuator, and various methods of using same. In one illustrative embodiment, the system comprises a first hydraulic cylinder, an isolated supply of fluid provided to the first hydraulic cylinder, the isolated supply of fluid positioned in an environment that is at a pressure other than atmospheric pressure, an actuator device coupled to the first hydraulic cylinder, the actuator device adapted to drive the first hydraulic ...