> For the complete documentation index, see [llms.txt](https://docs.aethlabs.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.aethlabs.com/microaethalometer-tm-ma450/quick-start-guide/important-information-before-getting-started.md).

# Important Information Before Getting Started

**1) The microAeth® Manager application** for MacOS and Windows can be used to modify all instrument settings; only some settings can be modified using the on-device user interface on the front panel of the MA450. For unattended outdoor deployments, the MA450's built-in WiFi (802.11 b/g/n) also enables remote data access once the instrument is configured.

**2) Timebase:** The MA450 can acquire data on timebase settings of 1, 5, 10, 30, 60, or 300 seconds. The 1, 5 and 10 second timebases should only be used under special circumstances where a decreased signal-to-noise ratio is acceptable; at these settings instrumental noise is larger and typically requires the highest flow rate and/or post-processing. For outdoor monitoring we recommend starting at the **60 second** timebase; longer timebases such as 300 seconds further reduce noise for stationary, long-term deployments.

**3) Flow Rate:** The MA450 pump can operate at flow rate settings of 100, 125, 150, 170 or 200 ml/min. A higher flow rate can contribute to greater measurement sensitivity but will use more filter tape and more power. **150 ml/min** is the recommended starting flow rate for the MA450.

**4) The lowest wavelength light source enabled will typically trigger the attenuation (ATN) tape advance threshold.** For example, if 5 wavelengths are enabled, the UV channel should always trigger the tape advance.

**5) Measurement Wavelengths:** What are you trying to measure? What wavelengths are important for your measurements? **More is not always better. Operating with the IR channel only will increase tape life by at least 2.3x** — worth considering for remote outdoor sites where tape changes are less frequent.

**6) Tape advance ATN threshold:** If DualSpot® is enabled, a higher ATN threshold can be used, as DualSpot will help correct for aerosol composition dependent loading effects.

**7) DualSpot® vs SingleSpot™:** A flow rate of 100 ml/min or greater is highly recommended when using DualSpot® loading compensation (the MA450's recommended 150 ml/min satisfies this). Using **DualSpot®** will allow measurements at higher ATN loadings (longer sampling at each filter tape location) as the data are compensated in the BCc data column.

{% hint style="info" %}
Due to the flow split between Spot 1 and Spot 2, the measurement sensitivity in DualSpot® mode will be lower than in SingleSpot™ mode for the same total flow rate. When the DualSpot calculation and compensation is active (when ATN for BC1 ≥ 3) the data will have more noise; this is expected behavior. Simple smoothing can be applied to reduce the noise, or the smoothed columns in the data file can be used if helpful.
{% endhint %}

**8) Protect the instrument, inlet, and outlet ports from water and other contaminants.** The MA450 is designed for outdoor deployment, but the inlet and outlet ports and all connections must still be protected from the environment:

* Install the included **MA450 Inlet Protection Kit** (or [Inlet Protection Kit WPK-20-25](https://github.com/AethLabs/aethlabs-manuals/tree/main/gitbook/accessories/inlet-protection-kit.md)) with its water/bug trap and rain protection at the inlet.
* Shield the instrument from **direct solar radiation** and mount it using the rear sun shield mounting locations.
* Carefully route all inlet and outlet hoses so that water cannot enter the ports.

{% hint style="warning" %}
Be sure that the aerosol inlet is at atmospheric pressure and that there is no differential pressure between the aerosol inlet and the operating environment. If sampling from a plenum or chamber, it must be at the same pressure as the instrument. If other instrumentation is measuring in parallel, always use a dedicated sampling line for the MA450.
{% endhint %}

For high-humidity environments, an optional built-in **Nafion dryer** is available to manage moisture in the sample stream.

**9) Power:** The MA450 is powered by **external 12V DC** and is intended for continuous outdoor operation. Connect the 12V outdoor-rated power adapter to the sealed M8 connector labeled 12V DC IN. If the optional built-in Nafion dryer is installed, a **second** 12V supply must be connected to the connector labeled DRYER 12V DC IN.

**10) Verify and calibrate flow.** Verify flow rates using the on-device **Test Flow** menu and an external AethLabs Flow Calibration Kit before deploying. The instruments are initially calibrated near sea level; only calibrate the flow system if there is an error in the measured flow. Calibrate at the deployment location, especially at **higher elevations**, to compensate for the change in altitude.

**11)** To get the best data from the MA450, we highly recommend that the instrument warm up for approximately **30 minutes** so that it can equilibrate.

**12)** If you change sampling settings or download data (non-streaming data), you must **stop the instrument measurement** before being allowed to make a change. Every time the measurement starts into the sampling mode, the filter tape cartridge automatically advances to a clean spot. Stopping and starting the instrument unnecessarily will therefore consume more tape than sampling continuously.