Water Activity Meter (Precision Psychrometer, Extech RH390) – Free US Shipping!


In stock (can be backordered)

SKU: DraminskiTGPro-1 Category:


At Showroom Coffee and Crop to Cup Coffee Importer’s quality control lab, and across our global supply network of farmers, coops and exporters, we use and recommend this water activity meter for stability and shelf-life analysis on green coffee.

Coffee and cocoa farms, importers and exporters and roasting facilities use this meter to analyze water activity inside the coffee.  Water activity in coffee is the measurement of how much water in the coffee is “unbound,” i.e. how much water is available to take part in chemical reactions that may result in oxditation, staling and growth of mold/fungi/toxins.   Low/correct water activity is a sign of careful and proper drying and storage at the farm or mill, and can be used as an indicator of good shelf life for the coffee.

Traders and roasters can use this lightweight and compact device to analyze quality during coffee soucing travel. This meter works on both Arabica and Robusta coffee and is trusted by professionals around the world working in a variety of environments.

Measure humidity and temperature simultaneously with the RH390 Precision Psychrometer from Extech. A dual-illuminated readout can be alternated to display wet bulb and humidity, or dew point and humidity, or temperature and humidity. This handheld device registers temperatures from -22 degrees to 199 degrees F (-30 degrees to 100 degrees C) and measures the full spectrum of relative humidity with ±2% accuracy between 20 and 90% RH. Complete with carrying case and 9V battery.

To use this effectively on coffee, we recommend you use an 8oz Mason jar (straight wall canning jar) to hold the green coffee, and drill a hole in the lid to fit the sensor probe.

Use of this product is not limited to coffee, and it can be applied on any grains or other prodcuts that can be analyzed with a Psychrometer.

[Quickstart guide]

Humidity 0 to 100%RH
Temperature (Internal) -22 to 199°F (-30 to 100°C)
Basic Accuracy ±2%RH, ±1.8°F/1°C
Max. Resolution 0.1%RH, 0.1°F/°C
Dewpoint -22 to 199°F (-30 to 100°C)
Wet Bulb 32 to 176 °F (0 to 80°C)
Dimensions 7.8×1.7×1.3″ (200x45x33mm)
Weight 7oz (200g)

This product ships free within the US! 

WE SHIP SUPPLIES WORLDWIDE.  Please contact us for bulk discounts or a shipping quote to locations outside the US.

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