293. Different Kinds of Meters. The housewife has need to be familiar with three kinds of meters—water, gas and electric. These are devices for measuring water, gas or electric current.
294. Construction of a Gas Meter. The interior of one type of gas meter (Fig. 158) is somewhat like a water wheel—the pressure of the gas pushes the wheel around. Every time a compartment full of gas passes a certain point, the gas flows out and the flange on the wheel trips a lever which moves the hand of the dial ahead, thus counting the emptying of the compartment. The gas in the compartment back of this then moves to this place. The emptied compartment is filled with more gas as it passes the inlet.
Fig. 158. Gas meter.
Fig. 159. Water meter.
295. Reading the Gas Meter. A gas meter is a device for measuring the number of cubic feet of gas which flows thru a pipe. Small dials with the numbers from one to ten and a hand for an indicator show the number of single feet, tens of feet, and thousands of feet, which have passed thru the meter. The reading on any date is the total amount of gas which has passed thru. To tell how much has passed thru the meter during any period of time, take the reading of the meter on the first date, as indicated in Fig. 158, and then take the reading on the later date and subtract reading one from reading two—the resulting figure is the amount of gas passing thru the meter between these two dates. When buying gas, always keep the readings of meters at the time when the gas man takes them. Gas meters often register more or less gas than is actually consumed. Gas companies are allowed a variation or tolerance of one per cent fast or slow, to two per cent fast or slow. Gas is paid for at a stated rate per thousand feet in most places.
296. Water Meters. The water meter (Fig. 159) is a device for measuring the number of gallons or cubic feet of water which pass thru a pipe. The reading of the meter indicates the total amount of water which has passed thru the pipe since the meter was installed. Water is paid for, unless purchased at a flat rate, at so many cents a thousand gallons or thousand cubic feet. One cubic foot is called in commercial transactions 7-1/2 gallons.
Fig. 160. Electric meter.