Document baKMjne01XKe9bYEjkXY12QwO

I p* i- 1?1 ;! 222 CHAPTER 10 1950 Guide Swine Bams Community swine bams, because of the extent of slop feeding and the absence of daily cleaning of the pens, are the most difficult farm buildings to ventilate satisfactorily. Farrowing pens, to which supplemental heat is supplied, present less of a problem. In all cases, good floor drainage to remove urine and excess spilled water is important. Temperatures of from 50 to 55 F are usually recommended for farrowing pens. It is desirable to maintain temperatures.above freezing in all other pens in community houses. For bams that are well stocked and adequately ventilated, this requires walls with an overall thermal resistance of from 3 to 6, and ceilings with 40 to 50 per cent greater resistance. Outlets. The outlet flue should draw air from a level of 15 to 18 in. above the floor. Equation 8 is the basic-formula for flue area, and gives reasonably good results when modified according to the chart, Fig.' 6: 5 X At A = ~vr (8) Inlets. At least one inlet flue should be used for each pen. Swine are given or select definite nesting places, and care must be exercised to avoid having inlets located over them. Total inlet area should be approximately 70 per cent of outlet area. The area of individual inlets is best determined from the total area re quired and the number that can be so installed as to meet previous speci fications. Inlets should deliver air from points 12 to 15 in. below the ceiling, or from a level deflector on a sloping ceiling. Poultry Laying Houses From the standpoint of ventilation, poultry laying houses may be divided into cold houses and warm houses. The former are uninsulated, except in the ceiling. The inside-outside temperature difference is seldom more than 5 F deg. In the warm house, because of insulation or supple mental heat, the temperature seldom falls below 32 F, and is usually above 45 F. Outlets. The outlet flue is best placed near the middle of the pen. It is advisable to limit the length of pens to 80 ft. The area of the outlet flue may be determined from Equation 9 and modified according to the chart, Fig. 6. ,, 2.5 X A,s A~ Vh (9) For a cold house the bottom of the flue should be at the level of the insulated ceiling. In warm houses the bottom of the flue should be 12 to 15 in. above the level of the floor litter. Inlets. Inlets may be approximately 60 sq in. in area. The total inlet area may be equal to 70 per cent of the outlet area. Inlets in cold and in warm houses should deliver air from points 12 to 24 in. above the floor._ In cold houses which normally do not have storm sash, windows may be" raised enough to give the desired area and be fitted with baffle boards to direct the air straight upward. In houses less .than 20 ft' in width, all inlets may be on one side. In wider houses, a rather uniform distribution of inlets is essential. Infiltration and Ventilation 223 GARAGE VENTILATION Because of hazards resulting from carbon monoxide and other physi ologically harmful or combustible gases or vapors in garages, the importance of proper ventilation of these buildings cannot be over-emphasized. Dur ing the warm months of the year, garages are usually ventilated adequately because the doors and windows are kept open. As cold weather sets in, more and more of the ventilation openings are closed, and consequently on extremely cold days the carbon monoxide concentration runs high. Many garages can be satisfactorily ventilated by natural means, par ticularly during the mild weather when doors and windows can be. kept open. However, the A.S.H.V.E. Code of Minimum Requirements for Heating and Ventilating Garages, adopted in 1935, states that natural ventilation may be employed for the ventilation of storage sections where it is practicable to maintain open windows or other openings at all times. The code specifies that such openings shall be distributed as uniformly as possible in at least two outside walls, and that the total area of such open ings shall be equivalent to at least 5 per cent of the floor area. The code further states that where it is impracticable to operate such a system of natural ventilation, a mechanical system shall be used and shall provide for either the supply of 1 cfm of outdoor air for each square foot of floor area, or for removing the same amount and discharging it to the outride as a means of flushing the garage.10 Research Cooperative research on garage ventilation, undertaken by the A.S.H.VJE. Committee on Research at Washington University, St. Louis, Mo., and at the University of Kansas, Lawrence, Kans., and tests conducted at the A.S.II.V.E. Research Laboratory, have resulted in authoritative papers on the subject. Some of the conclusions based on work at the Laboratory are: 1. Upward ventilation results in a lower concentration of carbon monoxide at the breathing line and a lower temperature above the breathing line than does downward ventilation, for the same rate of carbon monoxide production, air change and the same temperature at the 30-in. level. .. 2. A lower rate of air change and a smaller heating load are required with upward than with downward ventilation. 3. In the average case, upward ventilation results in a lower concentration of carbon monoxide in the occupied portion of a garage than that obtained with mixing of the exhaust gases and the air supplied. However, the variations in concentration from point to point, together with the possible failure of the advantages of upward ventilation to accrue, suggest the basing of garage ventilation on complete mixing, and an air change sufficient to dilute the exhaust gases to the allowable concentration of carbon monoxide. 4. The rate of carbon monoxide production by an idling car is shown to vary from 25 to 50 cfh with an average rate of,35 cfh. 6. An air change of 350,000 cfh per idling car is required to keep the carbon mon oxide concentration down to one part in 10,000 parts of air. REFERENCES 1 A.S.H.V.E. Reseakch Report No. 786--Infiltration Through Plastered and Unplastered Brick Walls, by F. Ci Houghten and Margaret Ingels (A.S.H.y.E. Transactions, Vol. 33, 1927, p. 377). No. 826--Air Infiltration Through Various .Types of Brick Wall Construction, by G. L. Larson, D. W. Nelson and C. Braatz (A.SH.V.E. Transactions, Vol. 35,1929, p. 183). No.851--Air Infiltration Through Various Types of Brick Wail Construction, by G. L. Larson, D. W. Nelson and C.