As the inventor of floating mechanical packing over a century ago, Cook Compression is unmatched in application experience. Cook has supplied rod rings for tens of thousands of successful applications worldwide.
Continued development, backed by experienced applications support, results in custom seal ring, pressure breaker, vent ring, and purge ring solutions that consistently outperform traditional approaches. A complete selection of materials, from bronze to high-performance non-metallics, dramatically improves packing ring durability in the most demanding applications.
The Importance of Rod Rings
Pressure packing rings serve a critical role in reciprocating compressors, providing a dynamic, mechanical seal around the piston rod and against the packing case cup to prevent leakage from the compressor cylinder.
Compressor reliability, efficiency, run times and operating cost-effectiveness can all be significantly improved by optimizing rod ring applications.
The pressure generated in the compressor holds the rings against the rod and cup face; when the pressure is zero, springs hold the rings to the rod. Standard sealing rings typically use a radial cut and tangent cut ring, plus a back-up ring. Potential leak paths are blocked by ring overlap.
Common types of rings in a packing case are explained below.
Pressure breakers do not seal gas but instead act as an orifice to regulate gas flow. Their primary function is to slow the backflow of gas on the suction stroke to avoid damaging rings and disengaging them from the rod.
Pressure breakers also reduce gas flow on the discharge stroke, decreasing the effective pressure on the remaining pocking rings.
Seal rings stop or restrict the flow of gas out of the cylinder and into the vent or distance piece.
Seal rings are designed to provide a complete seal, but all standard rings allow small amounts of leakage. Therefore, seal rings are typically arranged in series to sequentially reduce gas pressure across the packing case.
For operations requiring near-zero leakage, Cook Compression offers advanced low-emissions rod packing. This patented technology incorporates gapless ring designs to eliminate leak paths and reduce fugitive emissions below measurable limits.
Vent rings seal at the low-pressure end of the packing assembly to ensure that gas leakage is forced out of the vent connection rather than down the rod and into the distance piece.
Purge rings allow the use of an inert gas (usually nitrogen) barrier for added protection against emissions.
Cook Compression Advantage
- The broadest line of sealing products
- More products in more applications than any other sealing products provider
- High-precision manufacturing
- In-house injection and compression molding
- Ongoing materials development, including cooperative programs with renowned universities
- In-house laboratories and test compressors
- Extensive engineering and field support