Various U.S. and Foreign patents and patents pending.
D/A's patented cone spring design maintains a pre-load on the packing from the bottom side to fully compensate for temperature and pressure fluctuations. This provides a maintenance free fugitive emission control system. Use of a high-tech, ceramic ball - results in reliable, self-healing, bubble-tight closure.
D/A's bonnetless valve design prevents dangerous process blow-outs caused by broken off or accidentally unscrewed bonnets. This superior design eliminates the necessity for a bonnet locking device...because there is no bonnet.
The packing nut is provided with a locking bolt that maintains the factory tested seal loading. Seals above and below stem threads keep out contamination and seal in lubricant, thus controlling the number 1 cause of valve failure ... lubricant failure.