1535 Relative Humidity Transmitter - Novatech Controls

!13. TIME BETWEEN Set the time between purgesPURGESeg. a two hourly purge or a 100 hourly purge.Range:1–199 hours14. PURGE DURATION Set-up purge duration to a number between three and ten seconds. The filter is actually purgedin less than one second but three seconds are required for the purge flow switch to check thatthe filter is not blocked.Range:3–10 seconds15. PURGE FREEZE TIME After the purge period, the transmitter output will remain fixed (frozen) for an adjustableperiod. To allow the probe reading to return to the correct process level and avoid output‘bumps’. The freeze period time required will depend on the probe response time and thus itsdesign and whether it has a filter or not. To determine the required freeze time, manuallyperform a purge while the plant is in operation and note the time required for the reading toreturn to the correct process level within a reasonable tolerance.Refer to section 2.23, 'Calibration Gas Set-up Procedure'.Range:100–1000 sec. in 10 second steps16. CAL GAS Select 'Cal Gas' to have automatic system calibration checking. For example a check gas of 8% could be used to test a large scale signal calibration, and alarm if the result is out of thetolerance values in set-up #18 & 19.Options:No Cal GasCal GasDuring the timed calibration periods, the transmitter outputs will be frozen and the transmitterwill alarm if readings are not within the accuracy limits set in set-up 17 and 18 If autocal is notrequired enter ‘No Cal Gas’ and the transmitter will step to set-up step 23.17. OXYGEN CONTENT OF Enter value of Cal Gas 1 (to one decimal place).CAL GASRange:0.0–20.9 % oxygen18 MAX. ACCEPTABLE Maximum positive error above which the ‘AUTOCAL ERRORPOSITIVE ERROR HIGH’ alarm will be initiated after timed period in set-up 21.Range:0.1–3.0 % oxygen19. MAX. ACCEPTABLE Maximum negative error below which the ‘AUTOCAL ERRORNEGATIVE ERROR LOW’ alarm will be initiated after timed period in set-up 21.Range:0.1–3.0 % oxygenNOVATECH HUMIDITY TRANSMITTER Page 41