The Oudian floating Ball Valves have the following advantages:
Superior Sealing : Seat to ball sealing is further improved by allowing both the ball and seat to move. This provides a leak tight seal even at low pressures. The floating ball increases compression against the seat as system pressure increase.
Self Cleaning : The floating design allows entrapped fluid to be continually drawn from the valve cavity. The internal washing action keeps the seats free of contaminated ingredients and guarantees superior valve performance.  http://www.oudian-valve.com/