The Mark 618 is a spring-loaded pressure regulating valve for use in maintaining precise pressure set points in low pressure gas and liquid services. With inlet pressures up to 150 psi (10 bar), the Mark 618 maintains the downstream pressure at settings from 1" water column to 7 psi (3mbar to 0,5 bar). The Mark 610 is completely self-operated and requires no external source or air supply for operation.