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American Society o/.Heating and. Ventilating Engineers Guide, 1932 Two types of condensation meters are in general use; the tilting bucket meter and the revolving drum or rotor meter of which there are several makes on the market. ' . Condensation meters should not be operated under-pressure. They are made for either gravity or vacuum installation. Continuous flow traps and vented receivers ahead of gravity type meters are desirable. A typical gravity installation for a condensation. meter is shown in Fig. 5, while Fig. 6 is a gravity installation using a vented receiver ahead of the meter. Fig. 7 shows a vacuum instajlation without a master trap. The pipe discharge from the meter should be of ample size and pitched so as to rapidly remove the condensate from the meter. It is advisable to follow the instructions of the meter manufacturer in installing a meter- as the successful operation of any meter depends upon its being properly connected. Chapter 22--District Heating. load above 20 per cent of the capacity of the meter. This is desirable for accuracy as the differential pressure at light loads is too small to properly actuate the meter. A few general points to be considered in installing a meter of this type are as follows: 1. It is desirable to place the differential medium in a horizontal pipe in preference to a vertical one where either location is available. 2. Reservoirs should always be on the same level and installed in accordance with the instructions of the meter company. 3. The meter body should be placed at a lower level than that of the pressure differ ential medium. Special instructions are furnished where the meter body is above. 4. Meter piping should be kept free from leaks. 5. Sludge should not be permitted to collect in the meter body. " Fig. 6. Gravity Installation for Condensation Meter Using Vented Receivers Flow Meters Steam flow meters are available in many types and combinations as indicated in the subdivision of fluid meters on page 322. The orifice and plug meter is one in which the steam flow varies directly as the area of the orifice. The vertical lift of the plug, which is proportional to the flow, is transmitted by means of a lever to an indicator, and to a pencil arm which records the flow on a strip chart. The total flow over a given period is obtained by . plani-metering the area on the chart and applying the meter constant, Flow meters using an orifice, venturi tube, flow nozzle, or Pitot tube as the primary device are made by a number of manufacturers and can be obtained in either the mechanical or electrically operated type. The electric flow meter makes it possible to locate the instruments at some distance from the primary element which is not always possible with the mechanical flow meter. Flow meters employing the orifice, venturi tube, flow nozzle or Pitot tube should.be so selected as to keep the lower operating range of the: 324 Fig. 7. Vacuum Condensation Meter Installation without Master Trap 6. The meter body and meter piping should be kept from freezing temperatures. 7. It is best not to connect a meter body to more than one service. 8. Special instructions are furnished for metering a turbulent or pulsating flow. STEAM PER SQUARE FOOT OF HEATING SURFACE The following factors are used in New York City for the different classes of buildings listed. The factors are based on maintaining an inside temperature of 70 F for certain hours with a minimum outside tempera ture of 0 deg F, and an average of 43 F for the heating season of eight months (October 1 to June 1). In this group are six types of buildings: For manufacturing or commercial loft type where steam is used to heat the premises during the day hours to maintain 65 to 68 F from 9 a.m. to 5 p.m. No Sunday or holiday use and no night use. Factor: 325 lb per square foot of heating surface per season. 325