Providing Sealing Effectiveness
As fleets convert to compressed natural gas (CNG) as a more environmentally friendly fuel supply, filling stations encounter new challenges to longevity and performance.
CNG filling stations require small, often non-lubricated, compressors that run at high speeds and high pressures, with low emissions and effective oil control. This places a premium on sealing effectiveness.
Cook Compression answers that need with a wide range of sealing solutions using state-of-the-art designs and advanced materials technology.
Low-Emissions Rod Packing
Cook Compression ultra-low-leakage ring technology is optimal for small CNG compressors.
With a patented, gapless design, each set of packing rings provides greater sealing capacity than traditional ring sets, reducing the number of cups and rings required and thus reducing frictional heat generation. The technology also uses the compressive properties of the ring materials to seal in sequence through a compressor stroke, reducing ring wear and providing greater sealing effectiveness, especially at higher pressures.
Piston Rings and Riders
Cook piston rings and riders are engineered for maximum service life and reliability. Seal joints and multi-piece rings are used in higher stages to reduce blow-by, while side notches on riders prevent pressure loading under the ring.
Backed by an in-house materials development team, Cook Compression applies extensive expertise to select just the right filled PTFE or PEEK materials to provide reduced wear and withstand and disburse the heat generated at the sealing surfaces.
RTV oil wiper packing uses a proprietary knife-edge geometry to remove crankcase oil film wherever it contacts the rod, keeping oil from the fuel supply. The single-groove design of the RTV oil wiper improves gas sealing to reduce fugitive emissions, which is especially advantageous in short-frame CNG compressors that do not have a separate wiper housing.
Wiper packing geometry is combined with a material designed to improve oil-wiping efficiency. TruTech™ 3110, for example, is a PTFE-based compound engineered to provide a sharp wiping edge over extended use. It also allows the wiper rings to conform tightly to the rod surface, eliminating potential leak paths.
Ring Damped Valve
The intermittent running of fueling compressors, combined with their high speeds and pressures, can cause valves to fail prematurely. The Cook Compression Ring Damped Valve can extend valve life by reducing impact forces at these high speeds and protecting against impact fatigue.
For smaller valve envelopes, particularly in the later compressor stages, Optima™ Series plate valves provide a engineered solution that can fit nearly any valve envelope.