Recent years have been marked by increasing demands for a cleaner environment. This translates into unyielding regulations for emission control of hazardous materials.
In any industry that uses valves and piping, one of the primary concerns is the potential leak path through valve stem seals. Repeated cycling of a valve over time is usually the cause of fugitive emissions through the primary valve stem packing. Today, Media Containment Devices (Figure 1) provide a secondary sealing system for the valve stem that can also function as a monitoring system.
The modest investment in a Media Containment Device is well worth it given the potential for plant shutdown due to fugitive emissions, possible resulting EPA fines, workmen’s compensation issues, potential public relations fall out and possible resulting higher insurance premiums.
These new Media Containment Devices can be mounted to a valve in service without having to take the valve out of the line providing a secondary stem seal. They also contain a number of monitoring options for further security and early alerts. One of them is a sensing device (Figure 2) added to the Media Containment Device that provides a visual indicator.
Another option is a lubricant/sealant (Figure 3) for critical applications where fugitive emissions could be dangerous to plant personnel. A button head check valve can be used to inject a sealant into the Media Containment Device to provide a tertiary stem seal.
Lastly, a positive displacement air line can be connected with air pressure exceeding the valve line pressure (Figure 4.) The resulting positive displacement will prevent media leakage to the atmosphere.
Robert M. Donnelly is Vice President – Marketing at Flo-Tite Valves & Controls (www.flotite.com).