Butylparaben is a one of the parabens. It has the formula C4H9(C6H4(OH)COO). It is the butyl ester of p-hydroxybenzoic acid. It is the ester of butyl alcohol and p-hydroxybenzoic acid and is classed as esters and phenols. It can be used as a fragrance ingredient, as well as a preservative.
By-Pass valves are designed to maintain a minimum flow rate in heating systems fitted with thermostatic radiator valves. It is open under normal low-load engine running conditions, and closes firmly when positive pressure is present in the inlet manifold. When on-boost and changing gear, a sudden lower pressure condition is created in the manifold and the valve pulls open again directing pressurized air back to the turbo inlet.