Category Archives: Pressure Sensors

THE MARS SCIENCE LABORATORY (MSL) ENTRY, DESCENT AND LANDING INSTRUMENTATION (MEDLI): HARDWARE PERFORMANCE AND DATA RECONSTRUCTION

(excerpt from Page 8)

The MEADS pressure transducers are manufactured by Stellar Technologies, Inc. and are derivatives of off-the-shelf transducers. They are strain gage-type transducers with a range from 0 to 5 psia, outfitted at the manufacturer with flight electrical connectors, pressure input fittings, and mounting brackets. The transducers are not thermally compensated and they contain no electronics (electronics functions are performed by the SSE.) The transducers were calibrated with the SSE, as a subsystem, in combination with thermal/vacuum qualification at Langley. The calibration coefficients from this testing were then used to convert millivolts to pressures when the MEADS flight data was obtained. All of the hardware-related uncertainties were used in an error budget to ensure that the MEADS subsystem would meet the science objectives listed above.4

process is described in detail in Reference 4. In order for the MEDLI project to be allowed to install the MEADS pressure ports in the thermal protection heatshield, MSL required flight-like testing to demonstrate that pressure ports would not adversely affect the MSL spacecraft performance. Since pressure ports have never been installed in an ablating, planetary entry heatshield to measure surface pressures during entry, an extraordinary amount of arc jet testing was required to demonstrate compliance with MSL requirements. In addition, the MEDLI project needed to determine if pressures could be accurately measured in an ablating, pyrolyzing heatshield material. This resulted in a research and development test effort in addition to a demonstration test program to verify both the “do no harm” and the performance requirements of the pressure ports in the MSL heatshield.

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Miniature Pressure Transducer has Flush Diaphragm, Zero Dead Volume

The Series FT290 pressure transducers are designed for those applications requiring both a standard NPTmale process connection and a flush diaphragm with zero dead volume. These pressure sensors are designed with a unique diaphragm design which reduces stress levels caused by torquing a tapered thread into the mating fitting. Besides their small size (only 3.5 oz.), these pressure sensors are constructed of all welded stainless steel and can withstand demanding application environments.

The FT290 covers ranges from 2,000 to 10,000 psia/psig and provides 3mV/V full scale output with 10vdc excitation. Static accuracy is ±0.25% (BFSL). The operating temperature is -100°F to +300°F, and the compensated temperature range is from -65°F to +250°F.

Additional design features include low sensitivity to shock and vibration, and infinite resolution. The compact size of the Series FT290 pressure transducer makes it ideal for many metering and dispensing applications. Standard units are designed with 1/4” NPTM pressure fittings; optional sizes are available. Each unit is shipped with a 19 point calibration record traceable to NISTas standard.

Subsea Wellbore Pressure Plus Temperature Transducer

Stellar Technology’s Model PT36XX subsea wellbore pressure and temperature transducer delivers long-term performance in harsh subsea oil and gas exploration environments. It has a total error band of ±1% of full scale output and is designed for working pressures to 15,000 psi and seawater depths to 17,000 ft.  Both temperature and pressure sensors are located at the flush-end of the wellbore probe, a design feature that improves dynamic response and alleviates clogging.

This wellbore sensor includes dual pressure containment rated to 20,000 psi for increased reliability. In addition, the PT36XX is constructed with no external load-bearing welds thus increasing service life and improving field serviceability.

The PT36XX is constructed of Inconel and 316 stainless steel. It can be configured as a pressure only or temperature only unit. The standard unit incorporates a 3 1/16 inch API flange although customers can specify their flange of choice. Probe lengths are available in lengths of 3” to 24”.  Both probe lengths and electrical terminations are customer-specified. PT36XX is also available with dual redundant pressure sensors for extremely demanding applications.

Customers can select from numerous available electrical outputs; 4-20 mA, 0-5 Vdc, 0-10 Vdc, as well as digital outputs including RS232, RS485, and CANbus. The PT36XX is field proven with years of reliable use. Each wellbore transducer is shipped with a multi-point calibration record, traceable to NISTas standard. Material traceability is also available on request. Due to various configurations and customer-specified features contact the factory for pricing and delivery.

Pressure Sensor Built to Survive with Field-Replaceable Diaphragm

Stellar Technology’s Model GT100 is a robust, heavy duty pressure transducer designed as a solution to severe applications like rocket engine testing that can ruin a typical pressure sensor. Model GT100 features a cleanable pressure cavity and a stainless steel diaphragm which can be replaced in the field as needed, renewing the sensor in just a few minutes.

The GT100 has a standard output of 3mV/V and delivers linearity and hysteresis of 0.25% across pressure ranges from 150 psig to 20,000 psig. Exceptional thermal isolation ensures reliable performance over an operating temperature of -100°F to +300°F. The compensated temperature range is -30°to +170°F, which can be extended to -65°to +250°F.

This rugged stainless steel sensor has built-in overpressure protection and low sensitivity to shock, vibration, and thermal influence. Wiring is through a heavy-duty 6-pin stainless steel connector, and 4 pressure fittings are offered, depending on the range.

High Pressure-Fatigue Rated Pressure Transducer

Stellar Technology’s Series GT320 and GT32XX pressure transducers incorporate a proprietary sensor design with innovative electronics to provide a new high pressure/fatigue rated pressure transducer with a standard accuracy of 0.25% and upgraded accuracy of 0.1%. With pressure ranges from 20,000 psi to 100,000 psi, the Series GT320 and GT32XX transducers are ideal for high cycle applications as well as ultra-high pressure applications. The GT320 offers mV/V output and the GT32XX series provides high level current or voltage outputs as well as digital outputs including CANbus, RS232 and RS485.

Both products have been designed to accommodate customer-specified process connections for high pressure and electrical terminations. These products feature all-welded stainless steel construction, are shock and vibration protected, and have a zero adjustment pot as a standard feature. Stellar Technology provides isolated voltage output for the Series GT3200.

Stellar Technology’s Series GT320 and Series GT32XX are excellent sensor solutions for homogenizing, fuel injection testing, water jet cutting, hot/cold isostatic powder press, and metal injection molding applications.

Flush Diaphragm Pressure Transducer Features NPT Threads, Amplified Output

Stellar Technology Inc, offers the new Model FT29XX amplified pressure transducer. This rugged all-welded stainless steel sensor combines a standard NPTmale process connection with a flush diaphragm.  In addition, the FT29XX pressure transmitter is designed with internal signal conditioning. Customers can select 4-20mAcurrent outputs, numerous voltage outputs, as well as digital outputs including RS232, RS485, and CANbus. The unique design of the isolation diaphragm reduces stress levels normally caused by torquing a tapered thread into the mating fitting. The FT29XX introduces zero dead volume to the fixturing and resists the accumulation of residue that can clog traditional pressure ports. The sensing element is machined from a single piece of steel, making the FT29XX insensitive to shock and vibration. This unit is ideal for metering and dispensing operations, for the application of sealants and paints, or anywhere a flush diaphragm unit is desired.

The FT29XX has an operating temperature range of -65°to 250°F (compensated: -30°to +170°F). Pressure ranges are available from 0-50psi through 0-10,000psig/a. Burst pressure is at least 3X FSO range. This compact sensor weighs about 8 ounces, and delivers a static full scale accuracy of ±0.25% (BFSL). Each unit is shipped with a 19-point calibration record, traceable to NIST. The FT29XX integrates with a standard ‘bayonet’ style electrical connector.  Options include alternative electrical terminations and NPTM pressure fittings.

Clean-In-Place Pressure Transducer Features Flush Diaphragm

The Series FT31XX clean in-place (CIP) pressure transmitters are designed specifically to meet the rigorous demands of the wet and hostile environments of industrial process applications that use a flush diaphragm and Tri-Clover flange clamps. These pressure transmitters incorporate a one-piece, non-welded diaphragm for reliable performance and long life in process applications such as homogenizers, heat exchangers, filters, pasteurizers, emulsifiers, surge tanks, and biopharmaceutical mixers. In addition, the FT31XX design does not use an oil fill, thus eliminating the possibility of process contamination.

Users can select from analog outputs of 4-20 mA, numerous voltage outputs, as well as digital outputs ranging from RS232 and RS485 to CANbus. The FT31XX offers isolated voltage output as standard for voltage output units. All internal electronics are fully potted for shock and vibration resistance and thermal stability.

The Series FT31XX is manufactured from all-welded stainless steel and available in 1.5 inch and 2 inch Tri- Clover flange sizes. Pressure ranges extend from 5 psig to 10,000 psig.  This unit delivers 0.25% static accuracy and offers a large selection of options including various electrical terminations, temperature compensation ranges, media materials, zero and span pots, true secondary containment, and intrinsically safe ratings.  Each unit is shipped with a standard 15 point calibration record traceable to NIST.