REP - Evapco

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STRUCTURAL STEEL SUPPORT MODELS REP 217-111 to REP 224-920 L Option A: Suggested Three “I” Beam Arrangement W 5-1/8" Gap Dimension End Elevation Plan View Three “I” Beams Required (By Others) Dimensions Model No. W L REP 217-111 to 911 17’ 4-1/8” 10’ 5-1/4” REP 217-412 to 912 17’ 4-1/8” 11’ 11-3/4” REP 217-214 to 914 17’ 4-1/8” 13’ 11-3/4” REP 224-018 to 918 24’ 1-1/8” 18’ 0” REP 224-720 to 920 24’ 1-1/8” 20’ 0” MODELS REP 217-111 to REP 224-920 Option B Option B: Suggested Two “I” Beam Arrangement In Option B, the two cells are supported by two steel “I” beams running across the width of the cells. Consult your EVAPCO representative for this alternate steel support and factory certified steel support drawings. UNIT OUTLINE STRUCTURAL BEAM Notes: Models REP 217-111 through 224-920 1. These are suggested arrangements for preliminary layout purposes. Consult your EVAPCO representative for factory certified steel support drawings. 2. The recommended support for option A is structural “I” beams located under the outer flanges and running the entire length of the unit. The unit should be elevated to allow access underneath the unit and to the roof below. Mounting holes, 3/4” in diameter, are located in the bottom flanges of the pan to provide for bolting to the structural steel. 3. Beams should be sized in accordance with accepted structural practices. Maximum deflection of beam under unit to be 1/360 of the unit length, not to exceed 1/2”. 4. Beams should be level before setting the unit in place. Do not level the unit by shimming between it and the “I” beams. 5. Support beams and anchor bolts are to be furnished by others. 6. Dimensions, weights and data are subject to change without notice. Refer to the factory certified drawings for exact dimensions. 7. For alternate layout arrangements please consult the factory. NOTE: OPTIONAL BOTTOM CONNECTIONS WILL REQUIRE THE UNIT TO BE ELEVATED TO ALLOW FOR PIPING. 8
APPLICATIONS System Design REP Cooling Towers are constructed of heavy duty materials and are designed for superior performance providing long, trouble-free operation. However, proper equipment selection, installation and maintenance is necessary to ensure optimum unit performance. Several of the major considerations when designing and operating a cooling tower installation are presented in the following paragraphs. For additional information, contact your local EVAPCO representative. Air Circulation The location of a cooling tower is an important consideration when reviewing system design. Since cooling towers consume large quantities of air, adequate spacing around the unit is necessary for it to perform properly. The best place to locate any cooling tower is on a roof or at ground level away from walls and other obstructions. Cooling towers that are located in wells, enclosures, or are adjacent to high walls must be properly located to avoid the effects of recirculation. Recirculation occurs when some of the hot moist discharge air leaving the cooling tower flows back into the fresh air inlet. When recirculation causes the inlet wet bulb temperature to the cooling tower to be increased, the capacity of the cooling tower is decreased. Refer to EVAPCO Bulletin 311, Equipment Layout Manual, for the recommended layout guidelines for cooling towers. Maintaining the Recirculated Water System A cooling tower removes heat by evaporating a portion of the recirculated spray water. As a general rule, a cooling tower evaporates 3 US GPM per 100 tons of cooling capacity. As this water evaporates, it leaves behind all of its mineral content and impurities. Therefore, it is important to bleed an amount equal to that which is evaporated to prevent the buildup of impurities. If this is not done, the mineral content in the water will increase until the solids eventually deposit in the unit, causing heavy scaling. The bleed line should be installed in the external piping of the unit. It must be properly sized for the application and be provided with a metering valve and flow measurement device to allow for field adjustment of the bleed rate. Water Treatment EVAPCO recommends that all cooling tower users should consult with a reputable water treatment company familiar with local water conditions in order to determine the extent and type of water treatment program recommended for each specific application. Any chemical water treatment used must be compatible with the galvanized construction of the unit. If acid is used for treatment, it should be accurately metered and the concentration properly controlled. The pH of the water should be maintained between 6.5 and 8.0. In order to prevent “white rust”, the galvanized steel in the unit may require routine passivation of the steel when the system is operating in the higher pH levels. Batch chemical feeding is not recommended because it does not afford the proper degree of control. If acid cleaning is required extreme caution must be exercised and only inhibited acids compatible with galvanized steel construction should be used. Consult EVAPCO’S Maintenance Bulletin 112 for additional information. Capacity Control The design wet bulb temperature for which a cooling tower is sized occurs only a small percentage of the time. Since the wet bulb temperature is lower than design much of the time, and cooling loads tend to fluctuate, some form of capacity control will be required. The simplest form of capacity control is to cycle the fans on and off. However, this type of control results in larger temperature differentials and does not provide close control of the leaving water temperature. A better method of capacity control is to use two speed fan motors, which add a second step of control. Two speed motors are an excellent method of capacity control for the REP Cooling Tower. This arrangement gives capacity steps of 10% (fans off), 60% (Fans at half speed) and 100%. A temperature controller can be supplied to set control at 5& F increments, so that close temperature control can be maintained without excessive cycling of the fan motor. Two speed motors also reduce operating costs. At half speed, the motor draws approximately 15% of the full load power. Since the maximum wet bulb temperature and maximum load very seldom coincide, the cooling tower will actually operate at half speed about 80% of the time. Therefore, power costs will be reduced by 85% during the major portion of the year. A third advantage of two speed motors is that noise levels are reduced by approximately 6 dB when operating at half speed. Since both the load and wet bulb temperature are normally lower at night, the sound generated by the cooling tower will be substantially reduced during the most noise sensitive time period. For multiple cell units, both fan cycling and two speed motors can be used to provide additional steps of control. The combination of fan cycling and two speed motors offers a simple and inexpensive means of controlling unit capacity along with substantially reducing the energy costs of the cooling tower. Piping Cooling tower piping should be designed and installed in accordance with generally accepted engineering practices. All piping should be supported by properly designing hangers and supports with allowances made for possible expansion and contraction of the piping system. No external loads should be placed on the cooling tower connections. Do NOT anchor any of the piping supports to the cooling tower or its framework. Control of Biological Contamination Water quality should be checked regularly for biological contamination. If biological contamination is detected, a more aggressive water treatment and mechanical cleaning program should be undertaken. The water treatment program should be performed by a qualified water treatment company. It is important that all internal surfaces be kept clean of accumulated dirt and sludge. In addition, the drift eliminators should be checked periodically to ensure that they are clean and have not been damaged. Note: The location of the cooling tower must be considered during the equipment layout stages of a project. It is important to prevent the discharge air (potential of biological contamination) from being introduced into the fresh air intakes of the building. 9
Page 1 and 2: ® C O O L I N G T O W E R S IDEAL
Page 3 and 4: TWO CELL END INLET COOLING TOWERS I
Page 5 and 6: THERMAL PERFORMANCE REP 217-111 to
Page 7: THERMAL PERFORMANCE REP 224-018 to
Page 11 and 12: MECHANICAL SPECIFICATIONS Furnish a

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