Document 10dZNr74DgybLnwXd3JOLzkQX

American Society of Heating and Ventilating Engineers Guide, 1934 observing the outdoor air temperature. An accurate thermometer, calibrated in 1 deg divisions should be used. The thermometer should be mounted in the shade at about mid-height of the building and not too near the building wall or adjacent to an air outlet. The heat from a wall or roof which has been exposed to the sun is easily transmitted to a thermometer, with resulting high readings. Average Indoor Temperature. It is important to note that the capacity of an opening (such as roof ventilator) does not depend on the difference in the temperatures measured adjacent to the opening. It depends rather on the difference between the average temperature of the column of air inside the building and that outside. Indoor temperatures should therefore be observed at various heights to secure a good average. DAIRY BARN VENTILATION4 A successful barn ventilating system is one which continuously supplies the proper amount of air required by the stock, with proper distribution and without drafts, and one which removes the excessive heat, moisture, and odors, and maintains the air at a proper temperature, relative humidity, and degree of cleanliness. Barn temperatures below freezing and above 80 F affect milk produc tion. Milk producing stock should be kept in a barn temperature be tween 45 and 50 F. Dry stock, at reduced feeding, may be kept in a barn 5 to 10 deg higher. Calf barns are generally kept at 60 F, while hospital and maternity barns usually have a temperature of 60 F or somewhat higher. The heat produced by a cow of an average weight of 1000 lb may be taken as 3000 Btu per hour. The average rate of moisture production by a cow giving 20 lb of milk per day is 15 lb of water per day, or 4375 grains per hour. To set a standard of permissible relative humidity for cow barns is difficult. For 45 F an average relative humidity of 80 percent is satisfactory, with 85 per cent as a limit. Where the barn volume is within the limit that can be heated by the stabled animals, the air supply need not be heated. The air should be supplied through or near the ceiling. It is better to have the exhaust openings near the floor as larger volumes of warm air are then held in the barn and there is better temperature control with less likelihood of sudden change in barn temperature. If a cow weighs 1000 lb and produces 3000 Btu of heat per hour, arid if a barn for the cow has 600 cu ft of air space with 130 sq ft of building exposure, one cow will require 2600 to 3550 cfh of ventilation, depending'on the temperature zone in which the barn is located. The permissible heat losses through the structure, based on one cow and depending on the temperature zone, vary between 0.043 and 0.066 Btu per hour per cu ft of barn space, and 0.197 to 0.305 Btu per hour, per sq ft of barn exposure. ' For additional information oh this subject refer to Technical Bulletin, U. S." Department of Agriculture (1930), by M. A. R. Kelley. Dairy. Barn Ventilation, by F. L. Fairbanks (A.S.H.V.E. Transactions. Vol. 34. 1923). Cow Barn Ventilation, by Alfred J. Offner (A.S.H.V.E; Journal Section. Heating,. Piping and Air Conditioning, January, 1933). 68 Chapter 4--Natural Ventilation GARAGE VENTILATION On account of the hazards resulting from carbon monoxide and other nhvsiologically harmful or combustible gases or vapors in garages, the importance of proper ventilation of these buildings cannot be over emphasized. During 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 concentra tion runs high. Many garages can be satisfactorily ventilated by natural means6 par ticularly during the mild weather when doors and windows can be kept open. However, the A.S.H.V.E. Code for Heating and Ventilating Garages, adopted in 1929, states that natural ventilation may be em ployed for the ventilation of storage sections where it is practical 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 openings shall be equivalent to at least 5 per cent of the floor area. The code further states that where it is impractical to operate such a system of natural ventilation, a mechanical system shall be used which shall provide for either the supply of 1 cu ft of air per minute from out of doors for each square foot of floor area, or for removing the same amount and discharging it to the outside as a means of flushing the garage. Research Research on garage ventilation undertaken by the A.S.H.V.E. Com mittee on Research at Washington University, St. Louis, Mo., and at the University of Kansas, Lawrence, Kans., in cooperation with the A.S.H. V.E. Research Laboratory, and at the A.S.H.V.E. Research Laboratory has resulted in authoritative papers6 on the subject. Some of the conclusions from work at the Laboratory are listed below: 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 sCode for Heating and Ventilating Garages (A.S.H.V.E. Transactions, Vol. 35, 1929). Airation Study of Garages, by W. C. Randall and L. W. Leonhard (A.S.H.V.E. Transactions, Vol. 36. 1930). Carbon Monoxide Concentration in Garages, by A. S. Langsdorf and R. R. Tucker (A.S.H.V.E. Trans- actions, Vol. 36, 1930). , Carbon Monoxide Distribution in Relation to the Ventilation of an Underground Ramp Garage, by F. C. Houghten and Paul McDermott (A.S.H.V.E. Transactions, Vol. 38. 1932). -- Carbon Monoxide Distribution in Relation to the Ventilation of a One-Floor Garage, by F. C. Houghten and Paul McDermott (A.S.H.V.E. Transactions, Vol. 38, 1932). Carbon Monoxide Distribution in Relation to the Heating and Ventilation of a One-Floor Garage, by F. C. Houghten and Paul McDermott (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, July, 1933). Carbon Monoxide Surveys of Two Garages, by A. H. Sluss. E. K. Campbell and Louis M. Farber (A.S.H.V.E. Journal Section, Heating. Piping and Air Conditioning, December, 1933). 69