Document ZJXnVZx9VDVBoKB54Z2EoZOp8

American Society of Heating and Ventilating Engineers Guide The majority of the meters used by district heating companies f0 ,, sale of steam to their customers are of either the condensation meter type. Condensation Meters The condensation meter is a popular type for use on small and mi sized installations, where all of the condensate can be brought to a mon point for metering purposes. Its simplicity of design, ease in tes accuracy at all loads, low. cost and adaptability to low pressure di bution has made it standard equipment with many heating companies Two types of condensation meters are in general use; the tilting b meter and the revolving drum or rotor meter of which there are se makes on the market. Condensation meters should not be operated under pressure. They VvTf-. Chatter 24--District Heating - which records the flow on a strip chart. The total flow over a is obtained by plani-metering the area on the chart and --CP*n',S.npeertiohttdeersmisueosteiunrwgcoa--nn--s-toarnif-*tic. e. , venturi tube, flow nozzle, or Pitot tube !iW rimary device are made by a number of manufacturers and can e. P gj jn either the mechanical or electrically operated type. The "flow meter makes it possible to locate the instruments at some rlge from the primary element which is not always possible with the anicmaeltfelorswemmeptleory. ing the orifice, venturi tube, flow nozzle or Pitot should be so selected as to keep the lower operating range of the AIR. bv-pass Fig. 5. Gravity Installation for Condensation Meter Using Vented Receivers . made for either gravity or vacuifm 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. 4, while Fig. 5 is a gravity installation using a vented receiver ahead of the meter. Fig. 6 shows a vacuum installation 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. Flow Meters Steam flow meters are available in many types and combinations as indicated in the subdivision of fluid meters on page 379. 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 380 I* \ VACUUM LINE FROM radiators VACUUM TYPE CONDENSATION METER. w - -TO VACUUM PUMP V Fig. 6. Vacuum Condensation Meter Installation without Master Traf ,;I6ad 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 V 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 ?- ins3tr.uTcthioenms oeftethr ebomdeytesrhcooumldpbaenyp.laced at a lower level than that of the pressure differential medium. Special instructions are furnished where the meter body is above. .. > 4. Meter piping should be kept free from leaks. r;- , 5. Sludge should not be permitted to collect in the meter body. 6. The meter body and meter piping should be kept from freezing temperatures- 381 /