Setting up a three-way pneumatically actuated ball valve on an Enviremedial Services sludge treatment system. |
Another problem inherent to most ball valve designs is that the ball is engaged at the top only, which allows some unintended movement at the bottom of the ball. This results in uneven wear to both the orifice and ball, and ultimately allows debris to lodge underneath the seals and cause premature failure.
The Trunnion Difference
For these reasons, the Enviremedial team wasn’t certain the Plast-O-Matic ball valve would be the best choice for their application but considered the corrosion-resistant material advantageous and proceeded with testing. The difference in the Plast-O-Matic offering turned out to be a combination of key features unique among thermoplastic valves: Trunnion design, and a super smooth, mirror-polished ball, all manufactured to extremely tight tolerances.
Trunnion design means that the ball is held at the top and the bottom. Unlike a ball that is held at the top only, the trunnion engagement eliminates movement at the bottom of the ball due to process pressure or debris impact. Because of the tolerances and finish, the mirror-polished ball acts like a wiper on the seals, essentially cleaning the sealing surfaces at every actuation. These features combine to prevent uneven seat wear, eliminate particle entrapment, and allow the ball valve to work for extended periods of time in heavy debris and sludge. It also eliminates the need for excessively high torque, and the problems inherent to that type of actuator.
Based on successful trials in debris and sludge contaminated liquids, as well as a number of reference cases where Plast-O-Matic ball valves had been used successfully for many years, Enviremedial Services rewrote their valve specs around the Plast-O-Matic True Blue Ball Valves. Keogh said they’ve been very pleased with the results. “We’ve been using Plast-O-Matic ball valves and actuators for years with no failures at all,” he said. “We have approximately 150,000 cycles on many of their air-actuated valves and have yet to see problems.”
In spite of ball valves’ bad reputation for handling solids, Keogh said the Plast-O-Matic product has proven otherwise. “The valves and actuators are bulletproof, easy to maintain and very easy to rebuild,” he said. “We actually cracked one manual valve ball strictly from abuse on a sludge application. We took the valve apart - it was filled with mud. We cleaned it, glued the ball back together and it’s working flawlessly again!”
Considering the nasty stuff that Enviremedial Services’ equipment encounters, Keough said, “It’s a lot less stressful when you don’t have to worry about a valve failing 7,000 miles away.”
More WaterWorld Current Issue Articles
More WaterWorld Archives Issue Articles