RH Salt Solution Tests

The accuracy of RH BluePeg probes can be checked with RH test bottles, which contain saturated salt solutions to create a space with known relative humidities.

The most commonly used liquid is a saturated Sodium Chloride solution (NaCl) for 75% relative humidity. We also offer a 33% test bottle with Magnesium Chloride. Relative humidity values vary slightly with the ambient temperature.

Lignomat’s RH test bottles are equipped with Lignomat’s sleeves to accommodate RH BluePeg probes. A cable with sleeve-cover is included to make the connection to the RH probe and prohibit air from escaping during the test.

If the BluePeg probes are used for in-situ moisture testing of concrete, ASTM standard F2170 sets the requirements for calibration testing of RH probes. On-site testing with 75% salt solution bottles is allowed. Lignomat offers to check RH probes three times in-house free of charge during the first year.

Item Number: T-75/33


Product Description

A saturated salt solution can be used for checking the accuracy of RH probes. The science behind the test is, that a saturated salt solution will establish and keep a constant relative humidity in an enclosed space. Test bottles can be used multiple times if stored properly.

Most commonly used is a sodium chloride (NaCl) solution, which gives a nominal value of about 75%. This value is dependent on the ambient temperature. A chart comes with the test bottle showing, that for a temperature change between 60°F and 95°F, the relative humidity varies between 75.61% and 74.87%. 

The salt bottles have been adapted to fit Ligomat’s RH BluePeg probes. To accommodate the probes a shortened sleeve from Lignomat is inserted into the top of the bottle, another insert is placed at the bottom to stop the RH probe from dropping too low. The blue caps are used to close the bottle during storage. A cable with sleeve-cover is included with each test bottle.

After the cable is connected to the RH probe and the probe inserted into the bottle, the sleeve-cover is pushed into the lip of the sleeve to prohibit any air exchange and allow the air inside the bottle to reach the nominal RH value. Any of Lignomat’s RH meters can be used to measure the RH probes after acclimation:

— Ligno-Tec RH: RH only
— Ligno-DuoTec BW: RH and pinless
— Ligno-VersaTec: RH and pinless and pin 

If RH BluePeg probes are used for in-situ moisture testing of concrete in compliance with ASTM standard F2170, checking the calibration of the RH BluePeg probes with the 75% salt solution is allowed. Check for a difference of less than +/- 2% between the actually measured and the nominal RH value. For more requirements about RH probe calibration check see ASTM F2170 standard, available from the ASTM web-site.

Lignomat offers to check RH probes three times in-house free of charge during the first year.

For more information please contact Customer Service at 1-800-227-2105.

Lignomat USA Ltd, 14345 NE Morris Ct., Portland OR 97230, USA,
Email: sales@Lignomat.com, www.Lignomat.com