From a water maintenance point-of-view there are several contributing tasks that will promote performance and overall service life of electromagnetic stirring units. Aside from the collective concern about maintaining the water temperature, these tasks are fundamentally divided into different camps for either internally cooled or externally cooled units. However, all piping considered should be stainless steel. If the unit is cooled internally, the most important factor is making sure that flow is maintained through the unit. This can be accomplished by a constant monitoring of the flow meter. Once flow is verified, conductivity of the water should also be confirmed. While there is no catch-all number that can be appropriate for all applications, most agree that conductivity should remain less than 25 mu s. As mentioned previously, verifying functionality of the bleeder valve and making certain that all make-up water is treated with a suitable anti-corrosive and anti-freeze element as directed by the original equipment manufacturer is important. If the unit is cooled externally, there are a few more factors to be concerned with and a bit more of an ambiguous conclusion. For starters, water pH should be maintained as close to neutral as possible. Although most water systems function well within the acceptable range for the insulation to function, the closer to neutral that is maintained, the better. Because of the nature of the units, water flow is not usually a problem but still must be monitored and verified. A remaining paradox still needs considered. If the water system is exclusive to the externally cooled stirring unit and not used for cooling a corresponding power supply, conductivity of the water may just be an enigmatic factor. As controversial as it may seem, if the unit is insulated properly, water conductivity could skyrocket and theoretically not cause any faults within the unit. The question is: Does the DeI water cause enough damage to the core and steel within the unit and the insulation of the coil that the benefit of low conductivity is lost? Note that Del water attacks bare copper more aggressively than regular tap water, so herein lies the other problem. Does the DeI water contribute to the degradation of the insulation faster than regular tap water? Perhaps, but this is not certain. The best remedy for this is to be diligent about the insulation used on the coils and that the type and quality water is considered when supplying for a specific application. Since no two systems are alike, a thorough evaluation of a particular system be performed to determine the proper insulation required. Beyond this, remember that the application for virtually all electromagnetic stirring units is severe duty and impossible to assess applying laboratory conditions.
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