Below is a list of Miniature Check Valves manufacturers from Portsmouth, New Hampshire. Miniature check valves are designed for precision fluid and gas flow regulation in small applications where unidirectional flow is needed. These micro valves operate with the same components as larger check valves but with each element scaled down considerably. Whereas the diameter of an industrial sized valve and attached piping could be as large as several feet, as the swing check valve can be, many miniature check valves boast diameters as small as a quarter inch.