2018-11-1_PR Comm Packet - Laserfiche WebLink

Home

this could happen if brine cannot be better stabilized and residuals cleaned from the system. The current approach of leaving the brine alone if it is not corrosive is allowing residuals to build up in the system and we feel at some point this will eventually result in plugging of the cooling pipes and significant performance loss of the ice system cooling capabilities. A good program of testing should include: 1) regular testing; 2) results and analysis of the results; and 3) recommended adjustments to the brine. Key characteristics of the brine that should be monitored include: 1) level of inhibitor present; 2) dissolved copper and iron; 3) residual copper, iron and ammonia; 4) specific gravity; 5) pH; 6) clarity; 7) total Iron; 8) %calcium-chlorine; 9) freezing point; and 10) suspended solids concentrations. Recommendations for adjustment to the brine should be included with every test. Depending upon what improvements to the system are considered, it may be recommended that the brine be changed out when major improvements are made to the ice system. While disposal of the brine can be expensive, a well-balanced brine can provide for a more efficient operation. Other options to consider include a potential change to an ammonia/glycol system using a flat plate heat exchanger. Ethylene-glycol brine does not have the corrosion potential of calcium-chloride brine but is more expensive and has a reduced efficiency in heat transfer so overall efficiency cannot be determined without a more extensive study. The brine filtering system discussed earlier is constructed from iron materials and becomes challenging to operations due to excessive corrosion. We recommend a poly or fiberglass filtration system that is non-corrosive be installed with needed containment systems that would improve the efficiency of the brine filtration operation and result in a better stabilized brine. We suggest this upgrade occur only if calcium-chloride brine is used when major improvements are made to the ice system. Transmission Mains and Headers The buried transmission mains and headers are all fusion welded polyethylene from a Swedish manufacturer. The insulated transmission mains, ranging in size from four-inch diameter to eight-inch diameter, supply chilled brine from the refrigeration plant to the six zones of cooling found in the rink slab. The headers evenly distribute the brine from the transmission mains into the closely spaced one-inch diameter cooling pipes located in each zone of the rink slab. The pipe uses metric dimensioning and may require conversion fittings if connected to American- made pipe. There have only been a few leaks in the transmission mains over the past 25 years, with both occurring where the transmission mains connect to the headers for each end loop of the Oval. Both leaks occurred at the interface of the transmission main to the rink header and were the result of differential heaving of the rink slab and perimeter soils at that location that caused a shear stress on the pipe. We do not believe there has been any degradation of the polyethylene transmission pipe itself, but we have some concerns that the pipe may possibly be silting in from a slurry of precipitants, 151515