What are the considerations for the illustrated system regarding safety of the mechanical components? There is no low limit or high limit shown. Install low limits after preheat and cooling coils. The compressed air supply pressure must be under the ratings of the actuators as there are not relief valves shown for the PRV's. The upstream temperature of the preheat must be known. Add 30# relief valves after each PRV. What are the considerations for the illustrated system regarding energy use? The actuator spring ranges should be known. Pilot positioners or ratio relays will be required to sequence the four functions. Time actual time it is required to run must be known. What is a typical application of the type of system illustrated? Hospital OR's, school classroom supply, cafeteria/kitchen supply, for area with large exhaust requirements. How would you manually operate this fan system to address ventilation, comfort and energy use requirements under these different conditions? (1) At unoccupied times when the outside air (OSA) temperature is below 35F? Shut down if not required, with OSA damper closed and steam valve controlled from pneumatic low limit with automatic reset at 55°F. (2) At occupied times when the OSA temperature is below 35°F? Maximize heating with preheat coil and adjusting face & bypass dampers. Use reheat coil only after preheat arrangement is unable to attain desired supply emperature. (3) At unoccupied times when the OSA temperature is above 35°F? Same as number one. (4) At occupied times when the OSA temperature is above 35°F? Same as number 2, but shut down heating completely before gradually opening the cooling coil valve. 10-185 PRV1 PRV2 PRV3 STEAM CONDENSATE CWR CWS HWR HWS COOLING COIL HEATING COIL SUPPLY FAN PRV4 PRV5 DM1 DM2 NC NC NO PREHEAT COIL FACE & BYPASS DAMPER C NC NO NC C NO MAIN AIR SUPPLY SUPPLY AIR NO V1 V2 V3 OUTDOOR AIR
RkJQdWJsaXNoZXIy ODY1ODQy