Humidity Loggers 2YL-RH20-4M 2YL-RH20E-4M 2YL-RH23-4M 2YL-RH23E-4M 2YL-RH24-4M 2YL-RH24-E-4M
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External temperature and humidity sensors, 100mm long probe. 4 Million readings, operating range -40 to +90ºC, IP65 rated.

Supplied with YoyoLog View software, USB lead and long life battery.

Key Features
• Rugged IP65 housing
• Ideal for Ambient RH measurement
• Status LED: - Indicates Alarm - Low Battery Warning
• Internal Humidity and Temperature sensors

Download Brochure HERE

Dimensions (d x h)

50 x 130

Ambient temperature range -40 to +90
Measuring range -40 to +90
Accuracy ±2% RH and ±0.3
Internal sensor resolution 0.01 
Signal input
Memory capacity 4 million 
Active start • 
Sensor type 1 x 100mm Ext. Temperature + RH Steel Tube
Humidity Sensor
(Internal abd External)
0 to 100% RH/0.01% RH
Barometric Pressure Range & Resolution -
Intervals 1 second to 24 hours
IP rating 65
Battery type LITH-12

Battery life (Logging Speed)
1 minute

4 years
10 seconds 230 days
1 second 25 days
Robust, shock proof

Supplied with YoyoLog View software, USB lead and long life battery.

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Specs YY external T 20_23_25_61_90.jpg


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Wall Holder Enables you to securely install the logger onto walls. Complete with tamper-evident lead seal.

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Lead seal kit For Temperatue and Humidity LoggersContains 50 pieces of wire and 50 numbered lead tamper-evident seals for single use. These are manually closed around the wire and can only be released by cutting.


YoyoView Software In addition to the functionalities of the included basic software, the optional upgrade allows more complex analysis of data, creation of charts and calculation of data statistics.
» Three scaleable Y-axes
» Zoom function
» Cursor readings
» Display in spreadsheet format
» Combination of a series of measurements in one chart
» Definition of thresholds
» Y/T-charts (values over time)
» Statistics (min, max, and average values)
» Online metering (display actual values)

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Solar Radiation Screen Protecting the external humidity/temperature sensor from the effects of direct sunlight and rainfall when used in out-of-doors. Optimises measurement accuracy in eviromental / climatic data collection.

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Environmental monitoring

Room temperature monitoring, water temperature survey (rivers, lakes), outside temperature, research projects involving trees, ice


Logictics and transport

Monitoring of temperature and humidity conditions during transportation and warehousing for various goods such as frozen food, pharmaceuticals, live stock, chemicals


Drying processes

Food processing and manufacture; paint drying processes; curing monitoring



Storage rooms for medical, pharmaceutical products (qualification), chemical products



Humidity monitoring of seeds during production, pharmaceutical products