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more susceptible to changed pressure conditions than heating operations.

It may not be amiss to emphasize that the time element in many cooking operations is of much more importance than intensity.

WHAT IS USABLE NATURAL GAS PRESSURE.

The pressures carried by most natural gas companies have been too high for efficient service. This has had the further undesirable feature of teaching the consumer to believe that he was not receiving service unless the gas could be heard hissing through the orifice in the gas mixer. It has been demonstrated that 1—

1. Satisfactory cooking operations in frying potatoes, boiling potatoes, frying beefsteak, and pan-broiling beefsteak can be carried on with 0.2 ounce natural gas pressure. This merely requires that the short flame and cooking vessel be brought together. The changes in vessel position necessary to permit satisfactory operation at pressures as low as 0.2. ounce are easy to make, require no special changes in existing stoves, and consist merely, with drilled burners, in placing three nails in three of the drilled holes, and, with slotted burners, of placing three small pieces of tin in three of the slots, in order to support the cooking vessel at the proper distance from the burner, and close enough so that the short flame can do effective work.

2. Better results are obtained with pressures in the neighborhood of 2 ounces than at 4 ounces.

3. Less gas is used at pressures in the neighborhood of 2 ounces than at 4 or 5 ounces.

4. Manufactured gas range gives better results than natural gas range because the former is designed for low pressures.

5. There is very little difference in the time required to carry on cooking operations with pressures of from 1 to 5 ounces.

Therefore, if the consumer will use proper appliances, satisfactory cooking operations can be carried on with pressures as low as 0.2 ounce and the gas passing through the meter will perform a usable service.

With heating appliances, if the mixer is properly adjusted the combustion at low pressures can be made substantially as thorough as at high pressures, and the consumer can have the benefit of all the heat generated by the burning gas, although if the pressure is low he will invariably not have nearly as much as he would like to have or as he needs. However, all of the gas measured by the meter and burned in the heating appliance is used for a useful service, so far as it goes, although under extreme low pressure conditions there is not enough to give all consumers all they want.

1 Ohio State University Bulletin, vol. 22, No. 28, May, 1918: Effect of Gas Pressure on Natural Gas Cooking Operations in the Home.

ACCURACY OF METER REGISTRATION AT LOW AND VARIOUS GAS PRESSURES.

The popular belief is that meters run faster when the pressure is low than when the pressure is high. This is contrary to the facts. Variation in pressure makes no appreciable difference in the registration of the meter, the meter merely registering, within a reasonable limit of tolerance, the amount of gas that passes, and this is neither increased nor decreased by changes in pressure.1

EFFECT OF GAS PRESSURE ON GAS LEAKAGE.

A summary of gas leakage laws is given on page 58. From these it will be seen that the leakage at 4-ounce pressure is twice as great as at 1-ounce. For this reason the leakage in the city distributing plant and on the consumer's premises, which is paid for by the consumer because the gas must pass through the consumer's meter in order to leak away on his premises, will be substantially less if the distributing plant and consumer's fixtures are adjusted for low pressures rather than high pressures.

GAS METER FACTS.

The following features regarding gas meters should be borne in mind:

1. Gas meters have no power within themselves to register. The only way they can be made to register is by the passage of gas through the meter. The gas company has absolutely nothing to do with the operation, nor can it in any way control the registration of the meter. However, many times gas meters register when gas is not being used, due to leakage in house fixtures.

2. The gas consumption will not be increased by the use of a large meter.

3. The gas consumption will not be decreased by the use of a small meter. In fact, if the meter is too small the gas service will be unsatisfactory.

4. Gas bills are not made out regardless of gas consumption. While it is possible for the meter reader to make an error for one month, this will be automatically rectified in the reading of the following month.

5. High gas pressure does not increase or decrease the rate of registration of meter.

1 The same conclusion was reached in: Engineering Bulletin No. 2 of the University of Kansas, on Natural Gas: Its Properties, Its Domestic Use, and Its Measurement by Meters, under date of July 1, 1912. Paper on Value of Gas Delivered at Varying Pressures, by Charles V. Critchfield, of the Ohio Public Utilities Commission, read at the Pittsburgh meeting of the Natural Gas Association of America, May, 1918. Ohio State University Bulletin, vol. 22, No. 28, May, 1918: Effect of Gas Pressure on Natural Gas Cooking Operations in the Home.

6. Low gas pressure does not increase or decrease the rate of registration of the gas meter.

7. It is impossible for a gas meter to register twice. When the gas has passed through the meter it can not pass through the second time. 8. Meters do not always register fast. There are just as many times when they register slow, and this is to the detriment of the gas company.

DISTINCTION BETWEEN LUXURY AND NECESSITY IN NATURAL GAS SERVICE.

To the average family for cooking, hot water boiler heating, lighting, and incidental house heating service, natural gas is a necessity, but when used in larger quantities or for house-heating furnace work it becomes a luxury. Furthermore, the peak load characteristics of house heating furnace service make this service cost more to the natural gas company. An equitable schedule of rates ought, therefore, to provide for a fixed net price per thousand cubic feet for a large enough monthly consumption to permit of the cooking, hot water boiler heating, lighting, and incidental house heating service necessary in the average family. If this fixed consumption is exceeded, then the price of a thousand cubic feet for such excess consumption ought to be increased so as to make the consumer pay for the higher priced service he is receiving.

It is a trite observation that the luxuries of one day tend to become the necessities of the next. Most complaints for inadequate service during the few peak load hours, usually less than 1 per cent of the total 8,760 hours in the year,1 are based on the fallacy that a service that is purely a privilege has become a prerogative; that is, natural gas consumers as compared with other fuel users who have to use solid fuel or manufactured gas are a privileged class enjoying a luxury that is seldom appreciated until it becomes difficult to obtain, and on account of the limitations fixed by nature they do not possess and can not ask any inalienable rights of service, under conditions that are physically impossible to meet.

CONSUMER IS RESPONSIBLE FOR ECONOMIC USE OF GAS.

The consumer's use of gas has an important bearing on the efficiency of results that may be obtained, as discussed on page 40. Few. people appreciate that even in an ordinary frying operation effective results can not be obtained unless the vessel position is close enough to the flame so that the tip of the flame can deliver the heat generated in an effective manner. Even with high pressure and long flames, if a strong draft should deflect the flame the cooking service will be unsatisfactory.

1 Few people appreciate that even if the service averages below normal 5 hours a day for 17 days, the total period of normal service is still more than 99 per cent.

When mantle burners are opened so as to admit more gas than is necessary, the familiar "hissing" or blowing sound is produced. This has, first, a tendency to break the mantle and chimney; second, waste the gas; and, third, lowers the candlepower of the lamp. The majority of natural gas consumers do not appreciate that gas burners need care and attention and that periodic cleaning is absolutely essential if satisfactory results are to be obtained.

The data given on page 40 show the marked differences in results that may be obtained in using natural gas in the fire pot of an ordinary coal furnace, as against a specially built natural gas furnace.

BAROMETRIC CHANGES MAKE MORE DIFFERENCE ON TOTAL PRESSURE THAN GAGE PRESSURE VARIATION.

On account of the changing atmospheric conditions, the barometric pressure varies from day to day and from hour to hour on the same day. Thus, the atmospheric pressure. at Louisville, Ky., on January 21, 1918, was 30.47, and on January 11 was 29.19 inches, this difference of 1.28 inches of mercury being the equivalent of 0.627 pound to the square inch, or 10 ounces to the square inch, or considerably more than the entire range of variation in gage pressure.

ATMOSPHERIC TEMPERATURE CHANGES HEATING VALUE OF GAS MORE THAN CHANGES IN GAGE PRESSURE.

The variation in mean monthly temperature of natural gas at Louisville, Ky., is shown on page 45.

The variation in temperature of natural gas in the underground mains makes more difference in the heating value than the variation in gage pressure. The maximum fluctuation in temperature produces a difference in heating value of about 5 per cent, while the maximum fluctuation in pressure produces a difference in heating value of less than 4 per cent. Furthermore, these variations work in opposite directions; that is, in winter time when the pressure is low, therefore tending to decrease the heating value, the temperature is low, tending to increase the heating value. This increase due to low temperature will always be more than the decrease due to low pressure.

EFFECT OF PRESSURE OR TEMPERATURE CHANGES ON HEATING VALUE OF GAS.

These will produce changes in volume, but will neither destroy nor create any heat units, and hence will neither increase nor decrease the total number of heat units contained in the gas. However, the volumetric changes will always alter the distribution of the total number of heat units, as follows:

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FIG. 17.-MEAN MONTHLY TEMPERATURES OF NATURAL GAS IN GAS MAINS.

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