A Cobey Gas Seal Panel is designed to supply seal buffer gas to the shaft seals of various rotating compressors, providing containment of these process gases. The panel includes filters, pressure/flow control valves and various instruments to condition, control, and monitor the gas into and out of the dry gas seals.

Dry gas seals are basically mechanical face seals, consisting of a mating (rotating) ring and a primary (stationary) ring (Fig. 3). A sealing gas is injected into the seal, providing the working fluid for the running gap and the seal between the atmosphere or flare system and the compressor internal process gas.

Dry gas seals are mechanical seals but use other chemicals and functions so that they do not contaminate a process. These seals are typically used in a harsh working environment such as oil exploration, extraction and refining, petrochemical industries, gas transmission and chemical processing.

It is common for dry gas seals to exhibit excessive leakage to the primary vent immediately on startup after extended periods of compressor downtime. This condition, known as hang up, occurs when the balance diameter o-ring “sticks” to its mating (sliding) surface because of friction.

If the impression is made purely as a relief resulting from the greater pressure on the paper where the high parts of the matrix touch, the seal is known as a dry seal; in other cases ink or another liquid or liquefied medium is used, in another color than the paper.

Attributes

1. Check adhesion and remove all loose putty.
2. Clean and sand rebate.
3. Prime the rebate and allow to dry.
4. Cut the nozzle to form the glazing profile and apply DRY SEAL™ MP.
5. Smooth the surface by holding the applicator upright.
6. When cured, apply a paint or stain if required.

Since the late 1980s, end users have sealed their CO 2 applications with noncontacting dry gas seals optimized for fluids at or near their point of vaporization. The American Petroleum Institute (API) recognizes these seals as dual unpressurized seals, or tandem arrangements.

Multi-stage, “beam” style compressors require two seals, one at each end of the shaft (Fig. 1). Single stage, “overhung” style compressors require a single shaft seal, directly behind the impeller. Dry gas seals can be applied to accomplish the required shaft sealing.

Inboard of the dry gas seal is an inner labyrinth seal, which separates the process gas from the gas seal. Outboard of the dry gas seal is a barrier seal, which separates the gas seal from the compressor shaft bearings (Fig. 2).

A bidirectional seal provides protection from reverse rotation in situations such as the failure of dis- charge check valve and eliminates the need for spare seal cartridges on each end of a between-bearings centrifugal compressor. The spare seal cartridge can be installed at either end of the compressor.