Most users will not need to field calibrate. Aethair recommends sending gas sensor cartridges in for factory recalibration every 12 months, and that scheduled recalibration is the primary way to keep a cartridge accurate. The field calibration procedure in this guide is for correcting a cartridge that fails a bump test between scheduled recalibrations. If a cartridge is due for recalibration, or fails a bump test repeatedly, contact support@aethair.io rather than calibrating it in the field.
In this guide
This guide covers gas sensor cartridges first, then the same approach applied to non-gas parameters. Use the links below to jump to a section.
Overview
There are three related checks for an Aethair PRO gas sensor cartridge, listed here in order of rigor:
Quick response check confirms a cartridge is alive and reacting to gas. Informational only; never use its reading to calibrate.
Full bump test is a confidence check using zero gas and a known concentration of target gas, read in Environet. Confirms the sensor is reading within ±10% of the known concentration.
Field calibration is performed only when a bump test reading falls outside ±10% between scheduled recalibrations. Applies a correction multiplier in Environet so the sensor reports the correct concentration going forward.
Do not skip straight to calibration. Only calibrate a sensor after a full bump test shows it reading outside ±10% of a known gas concentration. Calibrating from an unverified reading, or from the quick response check, can make a good sensor read incorrectly.
What you need
Aethair PRO bump test bracket
Certified zero gas cylinder
Certified span (target) gas for the parameter under test, in date, at a known concentration
The safety instructions and Safety Data Sheet for each cylinder you are using
Regulator and tubing
Phillips screwdriver
Access to Environet to watch live readings and, if needed, create a calibration
Before you start
Confirm the Aethair PRO is powered on and reporting. The front LED should be solid blue.
Open the device in Environet and confirm the cartridge you are testing appears in the device details and/or the device calibration page.
Set the reporting interval short enough to capture the response. See Configuring Your Aethair PRO.
Test one cartridge at a time. Each gas sensor cartridge is held down by its own cartridge bracket, so only the cartridge under test is disturbed.
Understanding the bump test bracket
The bump test bracket fits over the cartridge bracket that already holds the cartridge in place. It does not replace the cartridge bracket. The four original screws are reused and pass through both brackets.
Four screw holes, one at each corner, aligning with the cartridge bracket screw holes
Two hose barbs on the outer face, positioned nearer one of the short edges
A recessed cavity on the opposite face, which seats over the raised top of the cartridge
Gas exhaust and ventilation
Follow the safety instructions and Safety Data Sheet provided with your calibration gas.Those documents are specific to the gas and concentration in your cylinder, and they take precedence over the general guidance below. Also follow your organization's own procedures for handling that gas.
The bump test bracket has two hose barbs: one inlet for gas from the regulator, and one outlet for gas leaving the sealed cavity.
Always connect tubing to both barbs. Routing the exhaust keeps test gas from collecting inside the enclosure or washing across the other installed cartridge, which can affect readings for parameters you are not testing.
Perform all bump testing in a well-ventilated area, regardless of which gas you are using. Where the exhaust goes depends on the gas:
Low-hazard gases (for example CO₂, methane, isobutylene for PID cartridges): route the exhaust hose away from the device and away from your breathing zone. A well-ventilated room is sufficient; a fume hood is not required. Note that methane and isobutylene are flammable, so keep the exhaust away from ignition sources and check the cylinder concentration against the gas's lower explosive limit before testing.
Toxic gases (for example CO, NO, NO₂, SO₂, H₂S, O₃, HF, HCl): route the exhaust outdoors, into a fume hood, or through a scrubber or activated carbon filter rated for the gas. Do not vent into an enclosed space such as a mechanical room, electrical room, or closet. Confirm the exhaust method against the handling instructions supplied with the cylinder.
Never plug or block the outlet barb. The bracket seals against the cartridge, so blocking the outlet pressurizes the cavity against the sensor face. This can damage the sensor and will produce an inaccurate reading.
Tubing material: For HF and HCl cartridges, use PTFE or PFA tubing. Both gases adsorb onto standard tubing, which slows the response and can make a functioning cartridge appear to fail.
Quick response check (optional)
Use this only to confirm a cartridge is alive and reacting, for example after an install, or before committing to a full bump test. It does not require the bump test bracket.
Apply a small flow of the target gas for 1 to 2 minutes at the air intake inlet on the right side of the Aethair PRO enclosure.
Watch Environet for a response on that parameter.
Not a calibration input. The cartridge is not isolated or flushed with span gas during this check, so the reading is not a verified concentration. Never create a calibration from this value. Use the full bump test procedure below instead.
Full bump test procedure
Step 1: Remove the Aethair PRO cover
Power off your Aethair PRO.
Unscrew the two screws on the rear of the device, above the power button.
Slide the cover upward and lift it off the enclosure.
Step 2: Install the bump test bracket
Remove the four screws from the cartridge bracket for the cartridge you are testing. Leave the cartridge bracket and the cartridge in place. The cartridge bracket is loose at this point, so avoid tilting or moving the device until the screws are back in.
Position the bump test bracket over the cartridge bracket, with the recessed cavity down toward the cartridge and the two hose barbs nearer the bottom of the socket. The barbs project straight out from the face of the bracket, toward you, not downward.
Reinsert the four original screws through both brackets and tighten them evenly until the bump test bracket is seated flush.
Leave the second cartridge and its bracket untouched.
Step 3: Apply zero gas
Connect the tubing from the zero gas regulator to the inlet barb, and connect a second hose to the outlet barb, routed as described in Gas exhaust and ventilation above.
Press and hold the power button on the back of the device until you hear a beep. The cover is off at this point, so the front LED is not visible; confirm the device is online and reporting in Environet instead.
Open the regulator and release the zero gas at an airflow rate of 0.3 liters per minute for 1 to 2 minutes.
Watch the reading in Environet and record the stable zero value.
Once complete, close the zero gas regulator and power off your Aethair PRO.
Step 4: Apply target (span) gas
Connect the tubing from the span gas cylinder to the inlet barb.
Power on your Aethair PRO. Listen for the beep, then confirm it is reporting in Environet.
Release the gas at an airflow rate of 0.3 liters per minute for 1 to 2 minutes.
Watch the reading in Environet and record the peak stable value.
Once complete, close the regulator and power off your Aethair PRO.
Step 5: Return to zero gas (recommended)
Switch back to zero gas following the same process and confirm the reading returns to the baseline recorded in Step 3. This confirms recovery as well as response.
Step 6: Remove the bump test bracket
Press and hold the power button until you hear a beep to power the device off.
Close the regulator and disconnect the tubing.
Remove the four screws and lift the bump test bracket off the cartridge bracket. As in Step 2, the cartridge bracket is loose while the screws are out.
Reinsert the four screws into the cartridge bracket and tighten them to secure the cartridge.
Power on your Aethair PRO, then confirm the cartridge is still reporting in Environet and that the reading has returned to ambient levels for the space.
Do not leave the bump test bracket installed after the test. While it is in place, the cartridge is sealed off from the surrounding air and the readings for that parameter do not reflect conditions in the monitored space.
Step 7: Replace the Aethair PRO cover
Align the cover rails with the grooves in the enclosure to ensure a proper fit. Once seated, replace the two screws on the rear of the device.
Interpreting the bump test result
Compare the span reading recorded in Step 4 against the known concentration of the gas you applied.
Within ±10% of the known concentration: the sensor is reading accurately. No calibration is needed and the cartridge is good to go.
Outside ±10% of the known concentration: record the known gas concentration and the sensor's reading, then follow the field calibration procedure below to correct it.
Record, for your maintenance log: the date, the gas concentration and lot number used, the zero reading, and the span reading.
If zero gas is not available on site, applying target gas alone still confirms that the cartridge responds. Treat that result as a functional check rather than a verified reading, since the baseline is unknown. Do not calibrate from it.
Field calibration: gas sensor cartridges
Perform this only after a full bump test shows a cartridge reading outside ±10% of a known gas concentration. Calibration applies a multiplier to the raw sensor output so it reports the correct concentration.
Before you begin, you need two numbers from the bump test: the known concentration of the gas you applied, and the reading the sensor gave while that gas was applied.
Step 1: Calculate the multiplier
Multiplier = known gas concentration ÷ sensor (instrument) reading
Two worked examples, both using a 100 ppm calibration gas.
Example: sensor reading low (needs to increase output)
Gas cylinder concentration: 100 ppm. Sensor reads: 90 ppm.
100 ÷ 90 = 1.11111, so the Calibration Params entry is 0,1.11111.
Example: sensor reading high (needs to decrease output)
Gas cylinder concentration: 100 ppm. Sensor reads: 110 ppm.
100 ÷ 110 = 0.90909, so the Calibration Params entry is 0,0.90909.
Step 2: Open the calibration editor
In Environet, open the device page for the Aethair PRO unit.
Click Edit on the device.
Find the Calibrations section and click + Create.
From the Parameters dropdown, select the parameter you are calibrating, for example Nitrogen Dioxide (NO₂).
Step 3: Enter the calibration parameters
The Calibration Params field shows two comma-separated values, 0,1, which represent the formula f(x) = 0 + 1*x. At those values the sensor output passes through unmodified.
Leave the first value at 0. Replace the second value with the multiplier from Step 1.
Step 4: Test the calibration
Click the Test button to reveal the Before and After fields.
In the Before field, enter the sensor reading from the bump test, which is the value Environet showed while the known concentration of target gas was applied.
Confirm the After value matches your known gas concentration.
If the After value does not land near your known concentration, recheck the multiplier before saving.
Calibration set to increase output: Before 90 → After ≈ 100
Calibration set to decrease output: Before 110 → After ≈ 100
Step 5: Save and verify
Click Create to save the calibration parameter to the device.
Re-run a short bump test to confirm the cartridge now reads within ±10% of the known concentration.
Record, for your maintenance log: the date, the parameter calibrated, the gas concentration and lot number used, and the before and after values.
This is a scaling multiplier, not a zero shift. With the first value left at 0, the formula runs through zero (f(x) = 0 + m*x), so it corrects the span response without adjusting the zero baseline. A zero correction is possible using the first value, but it is not part of the standard field procedure. If the zero reading was also off during the bump test, note that separately and contact support@aethair.io.
Custom calibrations do not survive a device reset. If the Aethair PRO is reset and a new initial configuration is created, saved calibrations are removed and must be re-entered. Keep your maintenance log so the values can be restored.
Field calibration: other parameters
Temperature, humidity, sound, and other non-gas parameters
The same field calibration approach applies to any other parameter the Aethair PRO reports, provided you have a certified reference instrument for that parameter.
At a high level:
Place a certified reference instrument for the parameter alongside the Aethair PRO, in the same conditions.
Let both readings settle, then compare the Aethair PRO reading to the reference instrument reading.
If the two agree within your acceptance tolerance for that parameter, no action is needed.
If they do not agree, calculate a correction multiplier and enter it as a field calibration parameter in Environet.
This does not override the factory calibration. A field calibration parameter is a correction layered on top of the sensor factory calibration, not a replacement for it. It can be edited or removed in Environet at any time without affecting the underlying factory calibration.
What you need
A certified reference instrument for the parameter you are checking, for example a calibrated thermometer/hygrometer or a calibrated sound level meter
Access to Environet to watch live readings and, if needed, create a calibration
A stable location where the Aethair PRO and the reference instrument will experience the same conditions at the same time
Before you start
Confirm the Aethair PRO is powered on and reporting, and that the parameter you are checking appears in the device details in Environet.
Position the reference instrument as close to the Aethair PRO sensor as practical, and allow both to acclimate to the environment before recording a reading. Avoid drafts, direct sunlight, or other localized effects that could make the two devices see different conditions.
Step 1: Compare the reference and Aethair PRO readings
Once both readings have stabilized, record the certified reference instrument reading.
At the same time, record the Aethair PRO reading for that parameter in Environet.
Record the date, the reference instrument identifier and calibration due date, and both readings, for your maintenance log.
If the two readings agree within an acceptable tolerance for the parameter and your application, no calibration is necessary.
Step 2: Calculate the calibration multiplier
If the Aethair PRO reading does not agree with the reference instrument, calculate a multiplier the same way as for a gas parameter:
Multiplier = certified reference reading ÷ Aethair PRO reading
Worked example, temperature. Certified reference instrument reads 50°F. Aethair PRO reads 45°F.
50 ÷ 45 = 1.1111, which is the multiplier you will enter in Environet. Because the Aethair PRO is reading low relative to the reference, the multiplier is greater than 1 to scale the output up.
The same logic applies in reverse. If the Aethair PRO reads higher than the reference instrument, the multiplier will be less than 1 to scale the output down. See the worked gas examples above for the increase and decrease pattern in more detail.
Step 3: Enter the calibration in Environet
In Environet, open the device page for the Aethair PRO unit and click Edit.
Find the Calibrations section click + Create.
From the Parameters dropdown, select the parameter you are calibrating, for example Temperature.
Under Calibration Params, leave the first value at 0 and replace the second value with the multiplier calculated in Step 2, which is 1.1111 in the example above.
Click the Test button to reveal the Before and After fields.
In the Before field, enter the Aethair PRO reading from Step 1, which is 45 in the example above.
Confirm the After value matches your certified reference reading, approximately 50 in the example above.
Click Create to save the calibration parameter to the device.
This is a scaling multiplier, not a shift. The formula runs through zero (f(x) = 0 + m*x), so it scales the reading proportionally. It does not add or subtract a fixed offset. If the parameter reads consistently off by a fixed amount rather than a proportional amount across its range, contact support@aethair.io before calibrating.
Step 4: Confirm the calibration
After saving, watch the parameter in Environet under normal conditions and confirm the reading looks reasonable.
If practical, re-check the parameter against the reference instrument once more to confirm the two now agree.
Record, for your maintenance log: the date, the parameter calibrated, the reference instrument used, and the before and after values.
Troubleshooting
If the cartridge does not respond
Confirm the cartridge appears in device details and on the configuration page of your Aethair PRO.
Check that the bump test bracket is seated evenly over the cartridge and that the four screws are tightened evenly. An uneven seal will let gas escape before it reaches the sensor.
Confirm the tubing is on the inlet barb and is not kinked.
Verify both cylinders are in date and the regulator is delivering flow.
Reseat the cartridge in its socket.
Repeat the test once with fresh gas.
If the cartridge still does not respond, or continues to read outside tolerance after calibration, contact support@aethair.io to arrange recalibration or replacement.
If a non-gas parameter still does not agree
Confirm the reference instrument itself is within its own calibration due date.
Confirm both devices were reading the same conditions at the same time, without drafts, direct sunlight, or other localized effects.
Allow more time for both readings to stabilize before recording them.
Repeat the comparison once more before adjusting the calibration parameter.
If a parameter continues to disagree with a certified reference after calibration, or the disagreement looks like a fixed offset rather than a proportional one, contact support@aethair.io for guidance.