0 5 20 25 30 10 15 -40°F TO 160°F 0°F TO 100°F 50°F TO 100°F 40°F TO 240°F RESTRICTOR 0 5 20 25 30 10 15 0 5 20 25 30 10 15 0 5 20 25 30 10 15 9.9 PSIG 5.1 PSIG 12 PSIG 9 PSIG RESTRICTOR RESTRICTOR RESTRICTOR 40 60 160 200 240 80 140 180 100 220 120 -40 -20 80 120 160 0 60 100 20 140 40 50 80 90 100 60 70 0 10 60 80 100 20 50 70 30 90 40 75°F 75°F 75°F 75°F #1 #2 #3 #4 15 PSIG 100°F 100°F 160°F 240°F 12 PSIG 87.5°F 75°F 110°F 190°F 9 PSIG 75°F 50°F 60°F 140°F 6 PSIG 62.5°F 25°F 10°F 90°F 3 PSIG 50°F 0°F -40°F 40°F #1 #2 #3 #4 PNEUMATIC TRANSMITTERS Most commercial pneumatic transmitters are one pipe, as illustrated; however, two pipe transmitters do exist. Note that they all have a 3 PSIG to 15 PSIG range regardless of their temperature, humidity, static pressure, etc. range. They only report the condition; they do not do the controlling. They are all direct acting; therefore, when the element loses its gas, a low value is simulated on the transmission signal. Most transmitters use restrictors in the range of .007”, but some use restrictors in the range of .005”. The graphs on pages 4.29 and 4.30 illustrate the relative air consumption of most of the manufacturers’ restrictors. Transmitters’ operational characteristics are very useful in energy conservation efforts. For Example: If the outside temperature is 10°F, the –40°F to 160°F transmitter will be sending a 6 PSIG signal to the control system, resetting the main heat to the building. If the area requiring the most heat over-rides that 6 PSIG signal with a 9 PSIG signal, via a selector, the control system will believe that the outside air temperature is 60°F rather than the true 10°F. This is the means of matching the main heat source temperature to the actual requirement of the coolest area of the building. 4.28
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