Recommendations For Measurements With The Vapo Meter - Delfin VapoMeter SWL5 User Manual

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ECOMMENDATIONS FOR MEASUREMENTS WITH THE APO ETER
The VapoMeter produces reliable results when the person-related, environmental and
instrument-related variables are controlled. The person-related and environmental
variables affect the absolute water loss. The instrument-related variables affect the
measured water loss value.
Guidelines for TEWL measurements (references 1-3 on page 12) are useful for
controlling the person-related and environmental variables, but the instrument-related
variables do not apply to the closed chamber method. The following recommendations
guide the measurement with the VapoMeter.
Instrument-related variables
Pre-measurement conditions of the unit
Relative humidity and temperature in the measurement chamber have to equal the
ambient conditions. Make sure that the VapoMeter is acclimatized to the measurement
conditions before operation. Take the unit out of the case to acclimatize. Make sure
that the measurement chamber is not exposed to humidity from skin, moist tissue or
water between the measurements. Do not hold the probe continuously in the hand or
near any source of heat or cold (pocket, electrical device, draft).
Timing of skin contact
Timing of the skin contact at the long tone is important. The VapoMeter uses the
ambient relative humidity right after the start command for calculating TEWL. The
calculated evaporation rate is not reliable, if the VapoMeter is very close to or touches
the skin too early.
Contact pressure
The probe needs to be against the skin to seal the measurement chamber. If there are
gaps between the skin and the adapter, causing airflow in the chamber, the measured
value is not reliable. Hard pressure on the skin may increase the TEWL. Thus,
maintain a constant light pressure, but make sure that the chamber is totally closed by
the measured surface. The measurement is orientation-free, horizontally positioned
surface is not needed.
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