The challenge with sealing pneumatically actuated control valves is to find the right balance between sealing performance and stem friction control. A higher packing stress would naturally lead to better sealing performance but at the same time lead to higher friction on the valve stem.
High stem friction is an issue particularly in pneumati-cally actuated valves due to the combination of a relatively low actuation force in combination with a need for high actuation accuracy.
A refinery in Slovakia was looking for a sealing solution for their Sulfuric Acid Fisher Control Valves that would give them the right sealing performance in combination with good actuator response.
The Leakage of sulfuric acid was causing environmental, health and safety and operational issues.
The Fisher OEM sealing solution was a PTFE wedge type packing which did not give satisfying results. The total number of valves was 20. The temperature of the sulfuric acid solution is 70-100°
The valves were sealed with the 1724E sealing solution consisting of die formed 1724 PTFE rings with a 5150 Live Loading system. The installation was done back in 2009 and the valves are still in operation. Style 1724E gives extremely well low emission results and has as well the lowest friction of all the available Chesterton packings.
Chesterton products used in the solution: Style 1724E Control Valve Sealing System
Makes valves compliant to stringent international emission legislation
- Provides extremely low valve stem friction