ESP Pressure Scanners are miniature electronic differential pressure measurement units consisting of an array of silicon piezoresistive pressure sensors, one for each pressure port. 

The sensors are mounted on a common hybrid glass substrate using a proprietary technique which maximizes long term stability.  The outputs of the sensors are electronically multiplexed through a single onboard instrumentation amplifier at rates up to 70,000 Hz using binary addressing.  The multiplexed amplified analog output is capable of driving long lengths of cable to a remote A/D converter.

The ESP scanners also incorporate a two position calibration manifold actuated by momentary pulses of control pressures.  When placed in the calibrate position, all sensors are connected to a common calibration pressure port.  A series of accurately measured pressures can be applied through this port to characterize the sensors, in place, at the condition to which they are being subjected.  Proper and periodic on-line calibration maintains static errors within +/-0.03% or better of the full scale (FS) pressure range.  The calibration manifold automatically switches between two common reference pressures to ensure a stable reference is applied during calibration.  The calibration manifold incorporates a visual position indicator and utilizes a dynamic o-ring seal design for high reliability and easy servicing in the field.

Options include purge capability, isolated from the pressure sensors, to clear measurement lines of moisture and contamination as well as to prevent closure of model pressure taps during application of pressure sensitive paint.  Other options include a nickel foil RTD output to monitor internal scanner temperature and Digital Temperature Compensation technology now incorporating PSI’s Gen-2 amplifier technology. 

The Digital Temperature Compensation (DTC) option incorporates the latest PSI innovations in ESP technology including temperature signal outputs from each silicon pressure sensor, embedded EEPROM retaining factory calibration information including temperature characteristics, programmable dual gain amplifier with optional dual range calibration, calibration manifold position sensing, and internal sensor excitation regulation with sense output.  DTC Series ESP scanners are supported by PSI’s DTC Initium System and the SDI configuration of the System 8400 to dramatically reduce calibration requirements. The ESP scanners are also supported bya variety of third party compatible systems.

Dated 10/09

1. Consult factory for pressure ranges not listed.
2. Maximum applied pressure without reducing sensor performance.
3. Static accuracy includes combined errors due to non-linearity, hysteresis, and non-repeatability.
4. Achievable static accuracy after span calibration. Consult applicable datasheets for DTC Series ESP specifications when used with PSI's System 8400 SDI configuration or DTC Initium system.
5. Typical performance using 2nd order equation of the form Px = C0 + C1 (Vx) + C2 (Vx)2
6. Typical performance using 4th order equation of the form Px = C0 + C1 (Vx) + C2 (Vx)2 + C3 (Vx)3 + C4 (Vx)4
7. Applicable when Dual Range Calibration is specified. Accuracy is expressed as a percent of the deranged Full Scale when dual range calibration is specified.
8. Each 16-HD supplied with intermediate cable terminating with 15-pin subminiature D-shell.
9. Heater chambers for DTC Series scanners are only required to maintain minimum operating temperature.

Specifications subject to change without notice.

ESP-Miniature Pressure Scanners User's Manual - August 1999

The Resistance Temperature chart below gives the characteristic of the temperature sensor used in the ESP Heater Chamber.

The following procedure can be used to adjust the heater to a different temperature (less than 80ºC scanner operating temperature).

1. Determine a control set point temperature fitting the application.
2. Connect an Ohmmeter to the two test points on the Heater Chamber.
3. Adjust the potentiometer until the value read from the chart is indicated on the meter.

   Note 1: This procedure results in a temperature setting within ±3º of the desired setpoint.

   Note 2: The heating element in the Heater Chamber can develop about 33 watts of power. The chamber provides insulation, however there are limitations for achievable regulation. The Heater Chamber reduces the temperature effect to the scanner by a factor of 10:1.

   Note 3: It is recommended to set the Heater Chamber temperature setpoint to 5ºC above the expected ambient temperature. Maximum scanner temperature environment is 80ºC.

   Note 4: For operation in a very cold environment (-50ºC), it is important to set the temperature to above freezing (0ºC), so water condensation does not occur.

   Note 5: Factory default temperature setpoint is 40ºC.

No. 0704