Once the strains are isolated from each other, any leakage must go to empty without any risk of one medium becoming blended with another. The valve is retained open from the liquid movement in the right direction. If your movement stops, the valve plug is forced in opposition to its http://valvesandfittings74173.thezenweb.com/Not-known-Factual-Statements-About-valves-and-fittings-28805751