HGM300 Refrigerant Gas Leak Monitor
NDIR Bench Measurement Description
Pyroelectric Detector
Sample Flow
| | NDIR Source | Dual Optical Bandwidth Filters | | |
| | |
Gas passing through the bench absorbs some I-R energy. Each of the 24 gasses in the onboard library has a very specific absorption signature defining the amount of energy any of these gasses will absorb in relation to the concentration present at the time of measurement. In order to increase accuracy and eliminate false alarms a narrow (8.1 to 9.4 uM) optical bandwidth filter is used to limit the optical spectrum to only those gasses listed in our library. All gasses outside of this bandwidth are ignored. The output voltage from the pyroelectric detector is processed to eliminate any extraneous noise, amplified, and digitized. This information is then sent to the onboard microcontroller, which analyzes and displays the data. The unit is purged automatically which brings in a clean air sample. This air sample contains no refrigerant gas, therefore, does not absorb any I-R energy. The energy measured in this purge sample is used as a reference or baseline, when calculating PPM values for actual input channels, which allows us to compensate for any changes that may occur over time in the measurement electronic circuitry, I-R source, or I-R detector. This also eliminates for field calibration of the unit. All measurements are temperature and pressure compensated to standard conditions to eliminate reading variability due to the climate or altitude of the unit.
What specifically makes the HGM300 Single-Beam-Single-Wavelength NDIR measuring bench so different?
1.) We gold plate the inside of the sampling tube. Gold is virtually untarnishable so this improves the reflecting properties of the optical path, which improves overall measurement bench sensitivity and accuracy.
2.) Because the optical properties have been improved we can reduce lamp intensity thereby improving the I-R source life, which improves long-term reliability. We estimate source life to be beyond 5 years.
3.) I-R source modulation is required of all such devices. We do this electronically thereby eliminating any mechanical parts and improving long-term reliability.
4.) Sample temperature changes can directly affect short-term measurement stability. Our auto rezeroing function engages every 10 minutes or whenever the sample temperature changes by more than 0.2 deg. C, or the enclosure interior temperature changes by more than 2.0 deg. C. Thereby, improving measurement stability and accuracy, and completely eliminating the effects of sample- component temperature drift anywhere in the monitor.
