In 1979, the DAN-EX Valve by Daniel Valve Company was introduced in Texas. The first iteration of this valve was created to improve what was then the General Twin Seal Valve. Between the years 1979 and 2000 over 8,000 valves were produced and installed worldwide. WesternValve then purchased the DAN-EX Plug Valve Company and currently manufacturers the original design valve and its aftermarket parts at its plant in California.