PMCQ 110-E_1210 final.pdf - EVAPCO Europe NV

E N G I N E E R I N G D ATA & D I M E N S I O N SApplicationsEVAPCO units are heavy-duty construction and designedfor long trouble-free operation. Proper equipmentselection, installation and maintenance is, however,necessary to ensure good unit performance. Some of themajor considerations in the application of a condenser arepresented below. For additional information, contact thefactory.Air CirculationIn reviewing the system design and unit location, it isimportant that proper air circulation be provided. Thebest location is on an unobstructed roof top or on groundlevel away from walls and other barriers. Care must betaken when locating condensers in wells or enclosures ornext to high walls. The potential for recirculation of hot,moist discharge air back into the fan intake exists.Recirculation raises the wet bulb temperature of theentering air causing the condensing pressure to rise abovethe design. For these cases, a discharge hood or ductworkshould be provided to raise the overall unit height evenwith the adjacent wall, thereby reducing the chance ofrecirculation. Good engineering practice dictates that theevaporative condenser’s discharge air not be directed orlocated close to or in the vicinity of building air intakes.Engineering assistance is available from the factory toidentify potential recirculation problems and recommendsolutions.For additional information regarding layout ofevaporative condensers, see EVAPCO Bulletin entitled“Equipment Layout”.PipingCondenser piping should be designed and installed inaccordance with generally accepted engineering practice.All piping should be anchored by properly designedhangers and supports with allowance made for possibleexpansion and contraction. No external loads should beplaced upon condenser connections, nor should any of thepipe supports be anchored to the unit framework. Foradditional information concerning refrigerant pipe sizingand layout, see EVAPCO Bulletin entitled “PipingEvaporative Condensers”.Water TreatmentIn some cases the make-up will be so high in mineralcontent that a normal bleed-off will not prevent scaling.In this case water treatment will be required and areputable water treatment company familiar with thelocal water conditions should be consulted.Any chemical water treatment used must be compatiblewith the construction of the unit. If acid is used fortreatment, it should be accurately metered and theconcentration properly controlled. The pH of the watershould be maintained between 6.5 and 8.3. Unitsconstructed of galvanized steel operating with circulatingwater having a pH of >8.3 or higher will require periodicpassivation of the galvanized steel to prevent theformation of “white rust”. Batch chemical feeding is notrecommended because it does not afford the properdegree of control. If acid cleaning is required extremecaution must be exercised and only inhibited acidsrecommended for use with galvanized constructionshould be used. For more information see EVAPCOBulletin entitled “Maintenance Instructions”.Control of Biological ContaminationWater quality should be checked regularly for biologicalcontamination, If biological contamination is detected, amore aggressive water treatment and mechanical cleaningprogram should be undertaken. The water treatmentprogram should be performed in conjunction with aqualified water treatment company. It is important thatall internal surfaces be kept clean of accumulated dirt andsludge. In addition, the drift eliminators should bemaintained in good operating condition.ENGINEERINGBleed-offEach unit supplied with a pump mounted on the side isfurnished with a clear bleed line for visual inspection anda valve which, when fully open, will bleed-off the properamount of water. If the make-up water supplying the unitis relatively free of impurities, it may be possible to cutback the bleed, but the unit must be checked frequentlyto make sure scale is not forming. Make-up waterpressure should be maintained between 140 and 340 kPa.21