Delmhorst Instrument HT-4000 - Manual (Page 6)

5
TO HOLD METER READINGS ON-SCREEN
1. To hold a reading on-screen while in measuring mode, press the SELECT
key.
2. Press the SELECT key again to resume taking continuous readings.
MEASURING RELATIVE HUMIDITY IN CONCRETE FLOOR SLABS IN
ACCORDANCE WITH ASTM STANDARD F2170
– USE SENSOR RH/T-S2
:
Select test locations to provide information about moisture distribution across the entire
concrete slab, especially areas of potentially high moisture, or if the slab is thick (>4 in.)
and air circulation is poor. For slabs on-grade and below-grade, include a test location
within 3ft of each exterior wall. Perform minimum three tests for the first 1000 ft sq and at
least one additional test for each additional 1000 ft sq.
1. Drill a 5/8” hole to a depth of 40% of the slab thickness using a rotary hammer
drill. Use a drill bit specially designed for rotary drills and with 3 or 4 cutting
edges to insure a smooth, round hole. Surface preparation is not required.
2. Vacuum the hole thoroughly, then use a wire brush to clean and loosen any
concrete remaining in the hole. Vacuum again and repeat the process a second
time.
3. Insert the yellow sleeve into the hole. Use silicone (or other water-resistant
sealant) to seal the interface between the collar of the sleeve and the concrete
surface. Use a hammer to insure the sleeve is fully inserted into the hole and
sealed to the concrete.
4. Insert the protective yellow cap into the sleeve and let the hole acclimate for 72
hours.
5. Remove the cap and immediately insert the sensor to full hole depth. Wait
minimum 1h and then take RH readings by connecting one end of the RH/T-C1
cable to the top of the meter and the other end to the exposed connector on the
sensor housing. Check for drift. The meter reading must not drift more than 1%
RH over 1 hour.