The TQC DewCheck 4 – Dewpoint Meter (DPM)/ Dewmeter is an extremely versatile dewpoint meter to measure and record all climate parameters required to treat surfaces. This easy to use and robust dewmeter conforms to ISO 8502-4 & ASTM D3276-07 and measures the relative humidity (%RH), ambient temperature (Ta) and surface temperature (Ts) and calculates the dewpoint temperature (Td) and the difference between the dewpoint temperature and the surface temperature (ÄT).