Mechanical seal designers face opposing challenges when developing dual seals. The requirement to provide optimised seal face cooling conflicts with the need to provide a seal that is tolerant of pressure reversal and abrasive or congealing fluids. Poor seal face cooling can potentially reduce reliability. The American Petroleum Institute mechanical seal standard (API682 ISO 21049) offers users a choice of three different configurations. Advantages and disadvantages are discussed of each type. Elegant designs are now available that can satisfy these opposing requirements. The use of CFD and testing has optimised these solutions. Field studies provide verification for these design concepts.
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