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Operation and Maintenance Instructions The water basin should be checked monthly and flushed quarterly to remove any accumulation of dirt or sediment which normally accumulates in the basin. Sediment can become corrosive and cause deterioration of basin materials. When flushing the basin, it is important to keep the suction strainers in place to prevent any sediment from entering the system. After the basin has been cleaned, the strainers should be removed and cleaned before refilling the basin with fresh water. Operating Level of Cold Water Basin During initial or seasonal start-up the cold water basin must be filled up to the overflow level. After the initial fill the pump may be started and the float valve should be adjusted to set the operating level for the unit. The normal operating level for MSS and AFT units is about 140 mm below the bottom of the air inlet louvre frames. The operating water level in the basin will vary slightly depending on the system specifics. The system load, bleed rate and make-up water pressure can all affect the operating level. If there are significant variations in seasonal ambient temperatures, it is possible that the water level may be higher in the winter time due to less load and evaporation. If an overflow condition occurs in the winter time it may be necessary to readjust the float valve to a slightly lower setting until overflowing no longer occurs when the pump(s) cycle off. The operating water level should be checked monthly and the float adjusted as necessary to maintain the recommended operating level. The ideal setting for operating level should yield a water level that rises to within 25 mm of the overflow when the pumps cycle off. Water Make Up Valve A mechanical float valve assembly is provided as standard unless the unit has been ordered with an optional electronic water level control or for use with field constructed basin. The makeup valve is easily accessible from outside the unit through the access door or removable air inlet louver. The makeup valve is a bronze valve connected to a float arm assembly and is activated by a large foam filled plastic float. The float is mounted on an all thread rod held in place by wing nuts. The water level in the basin is adjusted by repositioning the float and all thread using the wing nuts. Figure 8: Mechanical make up valve assembly Page 20 of 34 www.evapco.com.au sales@evapco.com.au
Operation and Maintenance Instructions The float position can be adjusted up or down as needed to achieve the correct operating level. The makeup valve and assembly should be inspected monthly and adjusted as necessary. If the valve shows signs of leakage the valve seal may need to be replaced. It is important to note that the make-up valve is sized to operate with supply pressures between 140 kPa and 350 kPa. If subjected to make-up water pressures in excess of 350 kPa the valve seals may fail prematurely. If make-up pressure is greater than 350 kPa it is suggested to install a pressure reducing valve ahead of the make-up valve. Pressurized Water Distribution System All EVAPCO units expect for AQXD and AQXS are supplied with wide orifice spray nozzles which should seldom need cleaning or maintenance however the water distribution should be inspected on a monthly basis to make sure that it is operating properly. Before doing anything, make sure the fan system is off and properly locked-out to prevent it from automatically or accidentally starting. The spray system can be checked for proper spray pattern with the pumps on, The spray system on LRTF, LRCF, and LRWF units can be seen after removing a few of the eliminators. For MSS, MEC and MFC the spray system can be viewed after opening the access port. If the spray nozzles appear to be getting low flow it may be due to a blocked strainer in the basin or debris that has lodged in the spray piping. If the nozzles have a build-up on them they can be cleared by using a metal spatula or flat-head screw driver to dislodge the accumulation. If an extreme build up of dirt or foreign matter occurs remove the spray branches to flush the debris from the header pipe. After the water distribution system has been cleaned the suction strainer should be checked to make sure it is in good operating condition and positioned properly so that cavitation or air entrapment does not occur. When inspecting and cleaning the water distribution system always check for proper orientation of the nozzles such that they are sprayed over the fill and not directed at the sidewall. Bleed-Off Valve The bleed-off valve, whether factory or field installed, must be checked weekly to make sure it is functioning and set properly. Keep the bleed-off valve wide open unless it has been determined that it can be set partially open without causing scaling or corrosion. Pump (When Supplied) Evaporative condensers and closed circuit fluid coolers are normally provided with a spray pump. The pump and pump motor should be lubricated and serviced in accordance with the pump manufacturer’s instructions as supplied with the unit. The spray pump should not be used with a VSD or as a means of capacity control. Excessive cycling of the spray pump increases the tendency for scale formation. Water Treatment and Water Chemistry of the Recirculated Water System Proper water treatment is an essential part of the maintenance required for evaporative cooling equipment. A well designed and consistently implemented water treatment program will help to ensure efficient system operation while maximizing the equipment’s service life. A qualified water treatment company should design a site specific water treatment protocol based on equipment (including all metallurgies in the cooling system), location, makeup water quality, and usage. sales@evapco.com.au www.evapco.com.au Page 21 of 34
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For Evapco Fibreglass Cooling Towers, Closed ... - EVAPCO.com.au

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