Upgrades to Direct Digital Control System (DDCS)

Relative Humidity Sensors/Transmitters: a. Provide sensor as solid state, resistance type relative humidity sensor of the Bulk Polymer Design. Provide the sensor element as washable and resists surface contaminations. b. Equip humidity transmitter with non-interactive span and zero adjustments, a 2- wire isolated loop powered, 4-20ma, 0-10.0 VDC linear proportional output. c. The humidity transmitter in accordance with the following overall accuracy including lead loss and A to D conversion. (1) Room Type Sensor: plus or minus 2 percent RH (2) Duct Type Sensor: plus or minus 2 percent RH d. Install outside air relative humidity sensors in a rain proof, perforated cover. Install the transmitter in a NEMA 3R enclosure with conduit fittings and stainlesssteel bushings. e. Provide a single point humidity calibrator, if required, for field calibration. Transmitters to ship factory pre-calibrated. f. Construct duct type sensing probes of 304 stainless steel and equipped with a neoprene grommet, bushings, and a mounting bracket.

Division 27 -	Communications, Common Work Results for Communications.
Division 28 -	Electronic Safety and Security, Common Work Results for Electronic Safety and Security.