Valves Instrumentation valves and couplings are used in process and measurement & control applications to direct and regulate flow, to isolate and protect instruments, and/or to take samples of gases or liquids. These valves are most often manual or mechanical in operation, size proportionate to the instrument lines, and manufactured to the same tight-tolerance specifications as the tube, pipe, and adapter fittings used alongside them in the instrument system. FloLok SSP Valves