Document Rj24vYxeBX8NZJ15ywoXa70bn

986 CHAPTER 48 1950 Guide COOLING WATER PIPING Many installations such as cooling towers, refrigeration systems and condensers require an adequate supply of cooling water. - For condensate piping, standard weight black pipe And cast-iron flanges are generally used. In refrigeration condensers, where water is the cooling medium, iron pipe is commonly employed. The friction loss may be determined from Fig. 4 for fairly rough pipe. If brine is the cooling medium, a correction for density should be applied. It has been found that a water velocity of about 6 fps gives the most economical results. Table 7. Maximum Daily (24-Hr) Requirements fob Hot Water in Gallons For. Apartments and Private Homes No. ov Rooms 1 2 3 4 .. 5 6 .7 8 9 10 < 20 1 60 70, 80 . 90 100 120 140 160 180 200 _ __ _____ .~ Room with basin................ ......... Room with bath--resident........... Public.basins-- ..................... Slop sink...................................... Number of Bathrooms 2 ,,- _ -- -- . 120 140 160 .180 200 220 240 260 280 800 _ ___ t 3 _ --. -- .-- -- 200 220.. .240 . 260 280. . 300 825 350 - 875 400 __ -- Hotels - 4 -- -- -- .-- . --. -- .. --; 250 ' 275 300 340380 '420 -460. 500 540 580 620 -- "7 5 -- -- -- .. -- -- -- -- -- -- 450 500 550 600 650 700 750 800 850 * Gal per 24 Hr ..................... 10 80 .. 100 .. 200. .. 150 -80 ' HEATING LOAD AND STORAGE CAPACITY The maximum daily and the maximum hourly hot.water demand form the basis for the selection of the,heater and the storage tank... Generally, in the residential dwellings, the maximum, daily, hot water.demand will be about 20-30 gal per person. The hot water used will ordinarily depend on the number of rooms and the number of bathrooms in any house or apartment. Table 7 gives estimates of the maximum hot water requirements in 24 In-in various types-of buildings. . In estimating the size of hot water storage tank required, and the heating capacity to be provided either from the boiler or from an independent domestic hot water heater, it is necessary to know the total quantity of water to be heated per. day, and the maximum amount which will be used in any one hour, as well as the duration of the peak load. . In cases where the requirements for hot water are reasonably uniform, Water Services 987 as in residences^ apartment buildings, hotels, and the like, smaller storage capacity is required than in the case of factories, schools and office build ings, where'practically the entire day's usage of hot water occurs during a veiy short period. Correspondingly, the heating capacity must be pro^ portionately greater with uniform usage of hot water than with inter mittent usage where there may be several hours between peak demands during which the water in the storage tank can be brought up to tempera ture. As a general rule it is desirable to have a large storage capacity in order that the heating capacity, and consequently the size of the heater, or the load on the heating boiler, may be as small as possible. In estimating the hot water which can be drawn from a storage tank, it should be borne in mind that only about 75 per cent of the volume of the tank is available, since, by the time this quantity has been drawn off, the incoming cold water has cooled the remainder down to a point where it can no longer be considered hot water. Table.8 Estimated Hot Water Demand per Person for Various Types of Buildings Type qp Building . Residences, apartments, hotels, etc. Office buildings Factory buildings Restaurants Restaurants 3 meals per day Restaurants l ineal per day Hot Water Required 40 gal per person per day* 2 gal per person per day* 5 gal per. person per day* 1.8 gal per person per mealb Max. Hourly Demand in- Rklatxon to Day's Use Duration op Peak Load Hours 1/7 4 . 1/5 2 1/3 1 1/10 . 1/6 8 2 Storage Capacity in Relation to Day's Use 1/5 1/5 2/5 1/10 1/5. 2/S Heating Capacity in Relation to Day's Use 1/7 - .1/8 1/8 1/10 1/10 1/6 At UO F bAt 180 F Where steam from the heating boiler is used to heat domestic hot water, , the computed load on the boiler should be increased by 4 sq ft EDR (equiva lent direct radiation) for every gallon of water per hour heated through a 100 deg rise. The actual requirement is (100 X 8.33)/240 = 3.48sq ft per gal of water heated 100 deg. The value of 4 allows for transmission losses, etc. There are two methods in common use for estimating the hot water requirements of a building: (1) by the number of people and (2) by the number of plumbing fixtures installed. Where the number of people to be served can be reasonably estimated, the data in Table 8 may be used. Example S. From Table 8, a residence housing five people would have a daily requirement of 5 X 40 = 200 gal per day, and a maximum hourly demand of 200 X 1/7 = 28-5 gal. The heater should have a storage capacity of 200 X 1/5 = 40 gal, and a heating capacity of 200 X 1/7 *= 28.5 gal per hr. The conditions given in Example 3 may be cited as average. It is pos sible to vary the storage and heating capacity by increasing and decreasing one over the other. - Such a-condition is illustrated in Example 4. _ ( i. Assume an apartment house housing 200 people. . From the data in Daily requirements 200 X .40 = 8000 gal. Maximum hours .demand b "- ' . /