Document 58w8rBzzE7Nwa88a96gL7GEV

American Society of Heating and Ventilating Engineers Guide, 1930 A = the Effective Temperature Difference, or the amount of variation from the ideal effective temperature. B = Dust Particles per Cu. Ft. C = Bacteria. D = Percentage of freedom from objectionable odors. E = Carbon Dioxide,, parts per 10,000. F = the Distribution Percent. The last column is the Percent of Perfect column used for plotting the final percentage. Each of these main columns is further divided into three smaller columns, the center one of which is left blank for recording the test data. To the left of this is the scale for the individual factor, effective temperatures in degrees, dust in particles per cubic foot, carbon dioxide in parts per 10,000, etc. On the right of each central column is the penalization scale. This is arranged with main graduations of 1 per cent which are numbered. Each graduation is further subdivided into fifths so that the scale may be read to 0.2 of 1 per cent on the scale, or by interpolation to 0.1 per cent. The chart gives not only final percentage of the test as a whole, but also indicates at a glance which factors are satisfactory and which at fault. In this way it is a con-' venient guide in correcting bad conditions, and bringing the final percentage up to the point desired. Making the Test In making a Synthetic Air Chart test the observer first divides the room by imaginary lines into small sections, each section having an area of approximately 200 sq. ft. of floor space. He locates an observation station in the center of each section. Taking a school classroom for example, the room should first be divided into four equalrec- tangular areas by imaginary lines bisecting at right angles through the center of the room. (See Fig. 11.) Four stations are now selected, one at the center of each rectangle. These stations are numbered 1, 8,3 and 4- It is always well to use a standard method of numbering stations, so that whoever reads the report can visualize each location. 106 Chapter 3--Standards of Ventilation . Standing at the rear of the room facing the teacher's desk No. 1 is the station nearest the teacher at her right. No. 8 is the one directly back of No. 1. No. S is the station nearest the teacher at her left, and No. 4 the remaining station. The tests are conducted in the following manner: Column A.--A Psychrometer reading is taken at each station beginning with 1, following with 8,3 and 4 The wet and dry bulb readings are separately recorded on the data sheet (Fig. 12) for each station. Column B.--Dust determinations are next made at stations 1, 8, S and 4, and the count of particles per cubic foot recorded from each station. The scale of the chart is arranged for a direct reading dust counter. If some other type of instrument is used, a correction factor is, of course, necessary. Column C.--Culture plates are next exposed to determine the bacterial content of the air. One plate is exposed at each station for two minutes, incubated, and the colonies that develop are counted and recorded for each plate. The average of all plates is plotted on the chart. mtUHO---------------------------------------------------------------- TEST DfJTfJ TEMfXPfTWPt m rtsit mm / c s 4 .1 6 7 t 9 19 . // FHX m MOWN MSI BffCTCJ&N ODO CO. DUtmiST KttfJTOa man C.F.M. tmf moan cr.M. !4 PRIfMUt JtMX IMPFCA.'JCH.______________________ NOTCA taoatrtBfr* physical srrnz /xjffxzrat occupant TOTAL (St -SUPPLY Cf CO. ax simr pet occupant er co.. ....................................................... MM me asmsunori X *900*3 m TYPE flee/? UAOce tBTu^aicafrmr two?enonrmason Munroro TYfK to. r* * tOBU. 7YMPDBY OtT manor. TWWt MY CKtCKID PV to. Fig. 12. Data Sheet for Synthetic Air Chart Test Oft. Column D--Odor determinations are made of the room as a whole. The observer should go outside of the room or preferably outside of the building for a few moments previous to making the test. He then enters the room quickly, and makes his determinations of the air in the classroom by means of the olfactory sense, recording the results whether perfect, very faint, noticeable, etc., in accordance with the following table. Freedom from Odors 100% Perfect 95% Very Faint 90% Faint 85% Noticeable 80% Distinct 75% Decided 70% Strong An Odorometer consists of a case of six vials each containing an odor substance in varying strength. It adds materially in classifying and standardizing odor perception. Its use, however, is not imperative. 107