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Sensit Wind Eroding Mass Sensor |
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Erosion monitoring solutions |
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August 2007: (sorry about the formatting, ask usoft!)
Sensor Sets New Standard
The new model H11-LIN replaces the model H11B,C
Outputs:
 | Particle count (PC) is simply a pulse indicating one particle impact, |
| Kinetic energy (KE) is a pulse representing a fixed amount of energy that has impacted the sensor. |
| NEW: Pulse height analysis (PHA) output is a pulse varying in amplitude with individual particle impacting energy. |
Inputs:
| +12VDC power |
| Gain select (1X, 10X) Can be selected via data logger output or hardwired (1X) by connecting this wire to ground or +12V (10X). |
Model H11-LINWiring Color Code
New Model Number -
H11-LIN
Outputs
| (brown) KE (mass flux) - pulse |
| (white) PC (particle counts) - pulse |
| (green) PHA (energy) - variable pulse height |
Input
| (blue) GAIN - 1X, 10X. |
Power
| (red) Power + 12VDC @ 70ma |
| (black) Ground |
Earlier Models - H11B or C
(Replaced by Model H11-LIN)
Outputs
| (brown) KE (mass) - pulse |
| (white) PC (particle counts) - pulse |
Alternate outputs (seldom used)
| (green) KE (mass) - variable pulse width |
| (blue) PC (particle counts) -variable pulse width |
Power
| (red) Power + 12VDC @ 90ma |
| (black) Ground |
Wind Eroding Mass Sensor
Backward Compatibility:
The new Model H11-LIN provides the same PC and KE outputs as previous Sensit sensors. It does not provide the seldom used toggled version of these outputs. The electrical current requirement is about 10% less than previous sensors.
Model H11-LIN improvements:
| New data output: The model H11-LIN has an additional output providing the kinetic energy of every individual particle impact. This data is in the form of a variable pulse height signal. A pulse height analyzer (PHA) module to capture this data should be available by the 1st quarter 2008. |
| Programmable Gain: Sensitivity can be increased by 10X externally via data logger or by physically connecting a wire to +12V. |
| Superior seal: The crystal mounts now extend over the ends of the crystals providing a superior seal and protecting the edges. |
| Lower power: The new sensor draws 70ma versus the previous 90ma current requirement. |
| Symmetrical response: Uniform radial response has now been achieved by chrome plating the crystal surface. |
| No multiple counts: Large energy impacts do NOT produce erroneous multiple counts. |
About the pulse height analyzers (PHA)
Background analogy – A PHA produces a graphical representation of a spectrum of pulse heights. The PHA is most commonly used in the field of nuclear scintillation. It is simply the counting and sizing of radioactive particle energy. The energy spectrum of radioactive atomic particles clearly defines a radioactive isotope similar to a mass spectrometer or gas chromatograph.
A pulse height analyzer is an instrument with a large number of counters. The number of counters typically vary from 128 to 4095 or more. Each counter is assigned to a small voltage range and is capable of counting up to 216 -> 220 per counter. Example: If the voltage range for incoming pulse heights is 4.095 Volts, and there are 4095 counters, a separate counter is assigned to count pulse heights over every 1mV portion of the 4.095 Volt range.
Sensit PHA data
The amplitude of each Sensit PHA output pulse is proportional to the energy transferred from one particle impact. A pulse height analyzer data acquisition module is being developed to acquire the large amount of data produced. It is anticipated this module will acquire up to 1000 sequential energy spectrum. This data may provide size fraction separation throughout an erosion event or other advanced data.
Sensit expects to have a PHA module available 1st quarter 2008. Alternatively, if your facility is technically inclined, you could build your own pulse height analyzer. The standard Sensit PC output pulse can be used as a “sync” pulse for your PHA. All you need to do is build a PHA performing a D/A conversion of the Sensit PHA output (0->4.095 Volts) within 40uS after the rising edge of the PC output. Your D/A resolution (8, 10, 20 bit A/D) determines the number of counters your memory must support. Use this A/D value to address a memory location where you read the value in that address, add one to it, and put it back. That’s all there is to it, except for dumping the memory via RS232, USB or whatever into your computer. They are really quite simply in their elementary form.
Gain Selection
Note: The dynamic range of the pulse height output covers fine to medium particle impact energies encountered during typical erosion events. The total dynamic range (105) of all possible eroding particle energies is too great to be covered by a single linear A/D system so we incorporated the selectable gain (X1, X10) to increase the sensors capability. This also allows superior application specific sensor operation.