The small size Double Block and Bleed valves are handwheel operated and the larger sizes are equipped with waterproof of gearing but operate in the same manner, proportionately requiring more turns. Turning the handwheel rotates the wedge 90 degrees, aligning the seating slips. The elastomer seal rings are Seating integrally bonded within the machined groves of each slip.

As the wedge lowers, it force the seating slips outwards, pushing the seals against the body and compressing them with in the grooves. With the slips solidly against the body, a secondary metal-to metal seat is formed on both sides of each seal, providing double protection. The wedging forces the seating slips outwards against the valve body and is perpendicular to the seats and the body. This eliminates all scraping and rubbing forces on the seals.

When opening, the wedge moves upwards and the dove-tailed (slips) are pulled away from the body. The wedge is guided by an upper and lower trunnion, and the wedge is rotated 90 degrees, aligning the seating slips. In the open position, the seals are completely out of the flow. Again, This action eliminates all scraping and rubbing forces on the seals.