Installing your EMs
Read the EM Product Materials:
EM Install Best Practices:
- EM21 and EM22 sensors are IP67 waterproof rated, meaning they are safe for splashes, mist, and dust exposure. They are not designed for prolonged submersion. If you wish to monitor temperatures of liquids, use the EM22, which has an external probe to measure the liquid temperatures.
- Sensors can be made water resistant with the addition of a silicone cover (purchase separately).
- Once you install your EM and it is powered on and activated in the Cloud, it will automatically connect to the IG that is either closest or has the best connection. Go to "Sensors" to see which Gateway it is connect to:
3. As a best practice for naming your Sensors, use this naming format: "ASSET NAME - MACHINE NAME." For example, "Site 1 - Fan 2." If you have multiple sensors on one asset, You can name them as such: ""Site 1 - Fan 2 - Sensor 1" and "Site 1 - Fan 2 - Sensor 2."
Connecting your EM21s and EM22s
Samsara Environmental Monitoring (EM21 and EM22) Sensors continuously measure environmental conditions and the data is instantly available in the Samsara Dashboard.
The EM21 is a wireless, waterproof, data logging environmental monitor with temperature and humidity sensors.
The EM22 adds an external temperature probe, which is to measure temperature in liquids and extremely hot and cold environments.
The EM21 and EM22 sensors have the following basic features:
- Continuous data upload to the cloud and Samsara Dashboard
- IP67 waterproof and dustproof
- Small, light-weight, ruggedized design
- 3-5 year battery life
- 100ft (30m) wireless range, depending on conditions
- 90 days backup data storage
EM21 Wireless Environmental Monitor (EM21)
The EM21 environmental monitor is a data-logging wireless monitor capturing temperature and humidity. The EM21 has built-in sensors to detect:
- Ambient Temperature between -40 and 60 Degrees Celsius (-40 to 140 Degrees F)
- Relative Humidity between 0 and 95%
Environmental Monitor with Probe (EM22)
The EM22 is a data-logging wireless temperature monitor. The EM22 uses an external probe to detect temperatures between -55 and 100 Degrees Celsius (-67 to 212 Degrees F).
Sensor operating temperature
Samsara Environmental Monitors are powered by lithium batteries that can operate within a wide range of temperatures without sacrificing battery life. Samsara sensors can be placed in most residential, commercial and industrial environments without adversely affecting their performance.
Samsara sensors can be placed in refrigerators and freezers for accurate temperature and humidity readings in those environments.
For temperatures below normal freezer temperatures (approximately -20 Degrees C or -5F), the EM21 will operate, however, for prolonged battery life we recommend installing an EM22 sensor outside the appliance and using the included probe to monitor the temperature inside the freezer.
Assigning Sensors to Gateways
To manually pin a sensor to specific Industrial Gateway, go to Settings > Sensors in your Samsara dashboard and select the Edit button on the sensor. In the Edit prompt, you can select a gateway you want your sensor assigned to and select Save.
Are EM sensors waterproof?
EM21 and EM22 sensors are IP67 waterproof rated, meaning they are safe for splashes, mist, and dust exposure. They are not designed for prolonged submersion. If you wish to monitor temperatures of liquids, use the EM22, which has an external probe to measure the liquid temperatures.
EM11 and EM12 sensors can be made water resistant with the addition of a silicone cover.
How are temperature sensors calibrated?
Samsara’s temperature monitoring sensors use thermistor-based temperature sensors to reliably monitor temperature without the need for periodic recalibration. The sensors use a Silicon Labs 7013 module which is factory calibrated and tested in a controlled environment.
This attached document certifies that each Samsara EM sensor has been calibrated and may be relied upon to read temperature and humidity according to the specifications noted in the EM series data sheet.
What does the "time constant" specification mean?
EM21 and EM22 environmental monitors specify a time constant in their datasheets.
A time constant is defined in science and engineering as the time it takes for a physical system to reach 62.3% of its total value. After 5 time constants, the system is considered to be at 100% value.
The actual time constant will vary based on the medium being measured.
For example, the EM datasheet defines the EM22 temperature probe's time constant as 5.00s.
If we imagine that the temperature in the air is 20ºC, the probe reads 20ºC, and then the probe is inserted into a stream of 10ºC water that is flowing at 1 m/s, it will take 5.00s to drop 62.3% of the way from 20 - 10º (in other words, after 5.00s the probe will read 13.77º).
After 5 time constants (25s), the probe will be considered to have reached the 100% value of 10ºC.
Do you have to recalibrate the EM sensors over time?
No - The temperature element in Samsara EM-family sensors is a thermistor. Thermistors are temperature sensitive elements with high sensitivity and accuracy, excellent repeatability, and resistance to drifting over time. Therefore, they do not need to be re-calibrated once deployed.
The thermistor elements are factory calibrated for the life of the sensor and will not drift or lose calibration unless exposed to extreme conditions outside the operating range specified on device datasheets.
Static temperature monitoring, such as logging and alerting on temperature and humidity in fridges and freezers, in restaurants and food preparation facilities, laboratories, factories, storage facilities and any other location where temperature is important.
Place multiple sensors around large spaces to more effectively monitor temperature and avoid hot spots. Place sensors near doors and other openings to see the effect of loading and unloading on temperature.
Temperature graphs can also reveal fridge and freezer compressor run times and cycle lengths, allowing you to adjust settings for higher efficiency or more stable temperatures. Combine this with Samsara power monitoring for ultimate visibility..
Easily log and review temperatures during shipment by third parties with Samsara environment monitors.
Send an EM21 along with your shipment to log temperature during the entire duration (up to 90 days) and the data will automatically upload to the Samsara Cloud as soon as the sensor comes within range of a Samsara gateway.
Place gateways at the source and destination to know exactly when your shipment leaves and arrives. Configure notifications to alert you of departure and arrival. Temperature violations will be alerted on as soon as the sensor arrives in range of a gateway.