NE74 Differential Pressure Sensors from Celsum Technologies

Pressure ranges ±150mbar to ±100 bars (2 to 1500 psi)
Over-range up to 10 x full scale
400 bar (5800 psi) line pressure for differential mode
Wet/Wet Differential, Absolute versions
Variable Reluctance stability & reliability
Insensitive to shock & vibration
Wide operating temperature range (-45 to +200°C)
All-welded stainless steel construction

The NE74 Series was initially developed for oil and gas exploration applications, but has also many other uses.

Typical applications include differential pressure measurement in down-hole installations with a very high over-range capacity, and depth measurement in high temperature and high vibration applications.

The NE74 pressure sensor uses the variable reluctance technique and consists essentially of a diaphragm made from a magnetic material mounted centrally between two end pieces, Each end piece consists of a fixed coil potted in high temperature resin and sealed by means of a welded stainless steel shim to completely isolate the coil from the pressure medium. The diaphragm is machined from a solid forged section and electron-beam welded to the end pieces. This produces an extremely rugged assembly with superb environmental characteristics and very good reliability figures (100,000 hours MTBF).

On the application of a differential pressure, the diaphragm is deflected, resulting in the inductance of one coil and a decrease in the other. This is detected by simple AC circuitry.

The LVDT amplifier that we supply has been used to condition the signal by some users. Also, the ADP15 range of process controllers has an LVDT input option.

Technical Specifications

Full Scale Ranges:

150, 350, 700 mbar
1, 2, 3.5, 7, 10, 20, 30, 70, 100 bar
5, 10, 15, 30, 50, 100, 150, 300, 500, 1000, 1500 psi

Over-Range:

10 x Full Scale

Line Pressure in Differential Mode:

<400 bar (5800 psi)

Performance:

Linearity:                    ±0.25% of Full Scale
Hysteresis:                ±0.15% of Full Scale
Repeatability:            ±0.1% of Full Scale

Electrical Characteristics:

Supply Voltage:         5V RMS 1kHz to 10kHz
                                     (optimum 3kHz to 4kHz)
Sensitivity:                 25mV/V ±50% at 3kHz
Output Impedence: 37.5 Ohms, approx 8mH
                                     (2 coils in parallel)
Input Impedence:    150 Ohms, approx 32mH
                                     (2 coils in series)
Insulation:                  > 100 Megohms at 250V

Mechanical Characteristics:

Electric Connections:      Solder pins
Pressure Connections:   Manifold mounting using
                                            O-ring seals
                                            Option of mounting plate with
                                            threaded pressure ports.
Wetted Materials:            17-4PH Stainless Steel
                                            Teflon® O-ring
Weight:                              100 grammes approx
Dimensions:                      Nom 27 x 27 x 30 mm Standard
                                            Nom 45 x 33 x46 mm Threaded Port Option

Environmental Characteristics:

G Sensitivity:                   <0.15P^(-2/3)% per G
                                           (where P is the pressure range of
                                           the capsule in psi)
Mechanical Shock:         1,000g for 1ms in each mutually                                            perpendicular axis will not affect
                                           the capsule

Temperature Coefficients:

Sensitivity:                      <0.05% of reading/°C nominal
Zero Offset:                    <0.03% of Full Scale / °C nominal
Operating Range:          -45 to +200°C
Storage & survival:       -60 to +220°C

ORDERING CODES:

NE74/A/BBBB/C/D/EE

where

A = Temperature Range: -45 to +200°C = H

BBBB = Pressure Range

C = Reference: True Differential = TD Absolute = A

D = Units: bar or mbar = B psi = P

E = Pressure Fitting* (Optional)

AA	1/8 BSP Male	HH	7/16 UNF3A Female
BB	1/8 BSP Female	SS	M8x1x4H Female
CC	5/16 UNF3A Male	TT	M8x1x4H Male
DD	5/16 UNF3A Female	UU	M10x1x4H Female
EE	3/8 UNF3A Male	VV	M10x1x4H Male
FF	3/8 UNF3A Female	WW	M12x1x4H Female
GG	7/16 UNF3A Male	XX	M12x1x4H Male

*NB Male = male 60° cone seat; female = 60°cone seat
All threads are male/external

For applications requiring specifications outside those listed,
please contact us.