Multis Hydro MJ810 series are suitable to equipment that is designed so that rotates at high speed and two fluids pass. This union was designed to carry two separate passage of media. This two passages union were designed to carry two different media in both passages. Having two separate sealing systems, even there were internal leakage, cross flow or mixing of the two media never occur. You may use this MJ810 when you have two different media which must not be mixed, or whose pressure differs a lot. If there were leakage, it can be out to the air through the Drain Port.