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Ventilation Rate |
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| Q: |
What is Ventilation Rate? |
| A: |
It represents how much air is introduced into the indoor space from the outside. Low values indicate low |
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ventilation rate and potentially poor air quality. High levels indicate excessive ventilation and potential. |
| Excessive energy usage. |
| Q: |
How does CO2 Monitor measures Ventilation Rate? |
| A: |
If one person in a room exhales out 18.5cc CO2 per breath and frequency is16/ min, then one person in a |
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room exhales out 300cc CO2 per minute. |
| - CO2 outside is usually 400ppm → X; CO2 in the room → Y |
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- The CO2 monitor can calculate the Vent Rate as 300/(Y-X) |
| Q: |
What is L/s/p or lps? |
| A: |
It's "liter per second per person". |
| Q: |
What is Cfm/p? |
| A: |
It's "cubic feet per minute per person". |
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Calibration |
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| Q: |
Preparation: before calibrating , you need standard gas or semi-standard gas. There are 3 methods |
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to get standard gas. |
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Method A: use CO2 in office/building |
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- Use two monitors (One is for calibration, one is calibrated (new). |
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- Use ambient room gas for calibration in office, wait at least 10min, until the CO2 reading doesn't |
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change.
(notice: user must not breathe toward the device, CO2 from the user will affect the reading) |
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- Use the reading of the new device as the standard. |
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- Calibrate the device using the process below. |
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Method B: use CO2 outsides |
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- Use ambient room gas for calibration outsides, wait at least 10min, until the CO2 reading doesn’t |
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change. (notice: user must not breathe toward the device, CO2 from the user will affect the reading) |
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- Use 380~420ppm as the standard reading. |
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- Calibrate the device using the process below. |
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Method C: use standard CO2 in the bottle |
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- Pump the standard CO2 gas (0~1000ppm, flux = 0.1~0.2 liter/min) into the ZG monitor from the Gas |
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Entry Hole, wait about 2~3min. |
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- Calibrate the device using the process below |
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Calibration process – can be found in the User Manual |
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The CO2 monitor has been calibrated in the factory and is suggested to recalibrate every12 months for |
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professional applications. Please follow below steps. |
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- If battery icon shows low power, please replace new batteries or use AC adapter.
- Press the Mode button(5), until CALI flashes.
- Press Enter(2), CALI shows on display.
- Adjust the lower display to ambient CO2 value by Up/Down (4/3) Button.
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Press Mode button (5) more than 10 sec., CALIBRATING flashes.
- Calibration will be done after 5 min and LCD will appear "PASS". If LCD appear "FAIL",
please calibrate once again.
- Press Enter(2), return to UserMode.
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| If user thinks the calibration result is not fine, he can use RcFS (Recover Factory Setting) to recover the |
| previous accuracy. |
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ABC (Automatic Background Calibration) |
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| Q: |
Do you have ABC for the CO2 monitors? |
| A: |
We use dual channel (beam) NDIR, thermopile from PerkinElmer, the sensor drift is less than 15ppm/ |
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year, so ABC is not necessary for our CO2 monitor. |
| Q: |
What is ABC? |
| A: |
The CO2 level drops to the outside level during unoccupied periods which eliminates the need of manual |
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calibration; but this will not work properly for applications in spaces without long unoccupied periods. |
| Q: |
How to ensure the CO2 long-term stability if without ABC? |
| A: |
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Many sensors experience long-term drift which may be resulted from various causes including gradual |
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chemical changes, exposure to water vapor, smoke, dust; and variations in the electrical power supply |
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like battery degradation, etc. |
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The problem of uncompensated drift is especially serious in NDIR sensors. For carbon dioxide |
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sensors that are used in fire detectors and in ventilation monitors the difficulty is much higher because |
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these devices are expected to operate for ong periods of time, even for years, without attention. These |
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applications require long-term stability to avoid of excessive false alarm rates and erratic ventilation. |
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The classic approach to solve this problem is to provide within the sensor a reference channel that |
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specifically measures the degradation caused by above mentioned factors. This increases the cost |
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and complexity of the sensor. We use dual-channel design, the sensor drift is <15ppm/year, which |
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helps to compensate the drift to maintain the long-term stability. |
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