Protimeter MMS Moisture Measurement System Page 19
A1.2 Equilibrium Relative Humidity Measurements in Solid
Floors
Note: See section 2.3 for basic Hygrometer Mode instructions.
In Hygrometer Mode, the Protimeter MMS can be used to measure the
equilibrium relative humidity (ERH) value of solid floor slabs. In essence,
this procedure measures the relative humidity (%rh) of a pocket of air that is
deemed to be in moisture equilibrium with the material under investigation.
Slabs that have an ERH value of 75% or lower are considered to be in a safe
air-dry condition. Slabs that have an ERH value of 80% or greater are
generally considered to be in a damp condition. Please refer to local standards
such as ASTM F2170 (USA) and BS8203:1996 (UK).
Note: These tests must be performed with the Hygrostick sensor only.
IMPORTANT: Moisture sensitive coverings that are laid onto damp floors
may fail in service.
A1.2.1 Sub-Surface ERH Test Procedure
(without using Protimeter Humidity Sleeves)
To perform the sub-surface ERH test, complete the following steps:
1. Drill 1/2” (12 mm) diameter clearance holes to a nominal depth of 2”
(50 mm) at the required points of measurement (POMs) and remove all
debris from the hole. Plug or cover the holes with suitable impervious
material. Ideally, the holes should be drilled 24 hours before measurements
are to be taken.
2. Push the Hygrostick assembly into the pre-drilled
hole and twist firmly to seal (see figure at right).
Ideally, leave the Hygrostick in the hole for 60
minutes before taking a reading.
3. Use the extension lead (supplied in the MMS kit) to
connect the Hygrostick to the MMS instrument
(having previously removed the protective yellow
Hygrostick cap, if fitted).
4. Select the Hygrometer Mode of operation (as
detailed in section 2.3).
5. Measure the %rh in the hole. This is the ERH value of the floor slab.
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