When El Paso Natural Gas Company first decided to gather some data from two or three outlying points and relay that information to a central location, there did not appear to be any great or insurmountable problems involved. We are still convinced of the veracity of the original conclusion, but we are also now aware of some of the myriads of small problems and able to give the reader a feel for our particular problems and their solutions.

As originally planned, there were some 41 quantities of analog information (15 second pulse duration) to be gathered from the locations of Phoenix, Tucson, and Casa Grande, Arizona. (See Figure 1). These quantities were to be relayed to a central Despatching location in El Paso, Texas. So far, how they were to be relayed, was open to good engineering practice, economics, and growth requirements.

ANALOG TELEMETER

The most straight forward method would be to relay the signals, or quantities, as they were, in analog form to the El Paso Dispatcher. Assuming that the Dispatcher could live with a time shared reading, three quantities could be displayed on a single recorder in the El Paso office. This would also necessitate 14 leased lines between El Paso and the outlying points. This requirement did not seem to fulfill our need of economics or future growth, to say nothing of good engineering. Just the array of recorders would eventually outgrow the wall space available.

USE OF INFORMATION

At this point it would be well to digress a moment and outline the use to which these particular readings will be used in order to clarify the following points.

The information to be gathered is natural gas pipeline static pressures and differential pressures obtained across orifice plate meters. The information is used to calculate instantaneous flow rates, accumulate gas volumes, figure line packs, to monitor pipeline conditions and to note trends.

The information was previously recorded on circular charts at the outlying locations and periodically the required information was phoned or teletyped to the Dispatcher in El Paso. The Dispatcher at the outlying point calculated all of the volumes and merely transmitted the end result.

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