If painting DRY SEAL do so within a month of application. If painting at a later date, lightly sand to create a key The inner labyrinth seal (or process labyrinth seal) plays an important role in the performance and reliability of a turbocompressor and its dry gas seals. The differential pressure across the inner labyrinth seal should be carefully monitored. This differential pressure needs to be maintained at a relatively constant designed value for uninterrupted and stable flow. A low seal gas flow (to process side) may cause migration of dirty process gas into the seal. A high flow may cause the flow coefficient in the system to exceed the designed value, creating detrimental flow turbulence, as well as inefficient performance. Remove all failed putty. The substrate must be free of oxidation, dirt, moisture, grease and residual putty, mastic or sealant. This makes Dry Seals a far superior option to using a wet seals solution. A wet seal solution to filling joints is enormously damaging to our environment as the amount of waste material generated worldwide is only adding to the severe global epidemic our planet earth is already facing due to the amount of plastic waste mankind is already generating.

Sometimes the differential pressure is higher than normally designed differential pressure, thus indicating a higher flowrate than designed; as noted it could result in inefficient performance or a malfunction. Often the differential pressure is lower than the designed value, which could be as a result of wear in the inner labyrinth seal. The final factor that influences the reliability of a dry gas seal is the auxiliary system. Typically, auxiliary systems (Figure 5) are chosen when the seal and seal supply are selected, as these choices have major influences on what is included in the auxiliary system. When identifying what to include in an auxiliary system, the reliability of the seal gas supply flow must be assessed to determine if it will provide a flow during all conditions, such as start-up and recycle. If an alternate gas is used, can pressure build up in the compressor be managed? The rotating seat is fixed to the compressor rotor, and the stationary face is connected to the compressor case. The stationary face must adjust axially to maintain the gap as the rotating face/compressor rotor moves and as the compressor case expands and contracts from changes in heat and pressure. To manage axial movement, the stationary face must move freely when required, and as a result, the dynamic secondary sealing design is key to attaining a response to axial changes without resistance or delay. Therefore, a reliable dry gas seal will have a parallel gap of 150 to 200 micro-inches between the rotating seat and the stationary face even when axial movement occurs.

Choosing a Seal Configuration

The operation range of seal system instruments: The instrumentation and control systems for sealing systems vary per application. In some of these applications, instruments or valves might be improperly specified. Sometimes the instrument range is not sufficient, and too often seal system flowmeters are not sized properly.

Material selection is critical for sealing elements. The compatibility of sealing element materials with process gas compositions in all operating cases (normal and abnormal) is important. These sealing elements require robust and sound designs to ensure long-term, trouble-free seal operation. Each of these sealing elements (U-ring, O-ring and V-ring) could easily be damaged in a careless installation or overhaul exercise. The deterioration of seal elements (such as different rings) could be due to abrasive wear from dirt or contamination from dirty process gas. Silicone has been used to seal building interiors and exteriors for close to a century because silicone sealants are ultraviolet (uv) stabilised and are resistant to harsh weather environments such as freezing cold and extreme heat. This is because the operational temperature range of silicone is -50 deg C to 250 deg C. However construction specifiers have been turning to pre cured silicone seals for the past few decades because a pre cured sealant system can handle at least 100 percent more expansion and at least 25 more compression movement than traditional ‘liquid applied ‘elastomeric sealants.Through all this, many dry gas seal designs were identified as unsuited for the applications in which they were installed—including the use of improper materials of selection that resulted in seal failures, incorrectly installed seals that limited seal life and poor dry-gas-seal panel designs that caused unnecessary compressor shutdowns. In many instances, when designing dry gas seal panels, little consideration has been given to piping configurations, auxiliary systems and utility costs even though all these affect the reliability of dry gas seals. One solution might be the double mounting of mechanical seals that provide the necessary lubrication, provided they are compatible with the product, which is not always possible.

Dryseal can easily accommodate most complex roof detailing and can be used on flat and low pitched roofs, on garages, extensions, or to replicate lead sheet on heritage buildings. Figure 3 shows a tandem-type dry gas seal with an intermediate labyrinth configuration for a centrifugal compressor application. The tandem seal with intermediate labyrinth purged with nitrogen is also a good fit for turbocompressors. In such a seal arrangement, nitrogen is injected between two seals. This action ensures the gas vented from the secondary seal will be mostly nitrogen during normal operation, since nitrogen supplied between the primary and secondary seals can be differential-pressure controlled to ensure it is higher than the primary seal vent. Adjoining Surfaces: Due to the thixotropic nature of this product, where it is applied by brush or roller, accidental contamination of non-target surfaces can usually be avoided by taking reasonable care. Typically, compressors with dry gas seals are used in applications in which they are critical parts of the entire process. A well-designed dry gas seal system will prevent extensive damage to the dry gas seal, compressor and process. Compared to pump operations, dry gas seals and compressors usually operate at higher speeds and pressures. Every component of a dry gas seal must be designed to manage exposure to extreme conditions. With its unique thixotropic consistency and excellent water repellent properties on a range of building materials, Dryseal Masonry Waterproofing Cream stands out.A minimum shaft speed is required for the operation of dry gas seals. This speed is known as the lift-off speed. Care should be taken for variable-speed turbocompressor operation (particularly steam turbine- and gas turbine-driven compressors) to ensure the operation is always above the specified minimum speed for the dry gas seals. Steam turbine- and gas turbine-driven compressors usually require cool-down operation at low speed after a shutdown and this low speed rotation should be performed with respect to the specified minimum speed for the dry gas seals. Historically, many dry gas seals have been damaged in low-speed operations.