CHAPTER 3 UTILITY TRANSMISSION AND DISTRIBUTION SYSTEM


FIGURE 3.20 A bank of bellows meters for a commercial multi-occupancy property. Diaphragm or Bellows—The most common meter that responders will en-


counter is the bellows meter. It is found in most residential and small com- mercial properties. Inside the meter there are chambers separated by a diaphragm that creates a bellows. The gas causes the bellows to fill and exhale as gas travels through the meter, running a counter device similar to an odometer. Rotary—Rotary meters can handle


larger volumes of gas and are usually found on commercial properties. They spin a blade as the gas travels through the meter, spinning faster with larger flows. Rotary meters also drive mech- anisms that calculate the volume of gas the customer is using like an odometer /counter.


FIGURE 3.21 A commercial rotary meter. Service Regulators


Service regulators are found at the customer meter. The controls lower the distribution pressure to a constant pressure to meet the customer’s de- mand. Customer delivery pressure


in residential services is normally 1


/4 pound of pressure or, as gas compa-


nies refer to it, 7 inches of water column. When there are no regulators at the meter the pressure has been already reduced to the 1 pressure.


/4 46


pound of


FIGURE 3.22 Service regulator.


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