Mechanical seal advantage

Interna] and External Seals Mechanical seals are classified broadly as internal or external. Internal seals (Fig. 10-112) are installed with all seal components exposed to the fluid sealed. The advantages of this arrangement are (1) the ability to seal against high pressure, since the hydrostatic force is normally in the same direction as the spring force (2) protection of seal parts from external mechanical damage and (3) reduction in the shaft length required. 

The majority of mechanical seal manufacturers make models that incorporate o-rings as secondary seals. These o-rings offer advantages over other forms of secondary elastomers. 

Tandem mechanical seals, lubricated and blocked by a seal gas with slightly higher pressure than the gas discharged by the compressor offer major advantages. There is no contami... 

Magnetofluids sealing advantages compared with mechanical seals are sealing without leaking, life time ( 5 years), only viscous friction, zero contamination, field operation (high vacuum (10-8 mbar) at approx. 10 bar), relatively simple construction and low manufacturing cost (www.roseal.topnet.ro). 

The first continuous distillation tower built was the "Patent Still" used in Britain to produce Scotch whiskey, in 1835. The patent still is to this day employed to make apple brandy in southern England. The original still, and the one 1 saw in England in 1992, had ordinary bubble-cap trays (except downpipes instead of downcomers were used). The major advantage of a bubble-cap tray is that the tray deck is leakproof. As shown in Fig. 4.5, the riser inside the cap is above the top of the outlet weir. This creates a mechanical seal on the tray deck, which prevents hquid weeping, regardless of the vapor flow. 

Hydride Compressors using reversible metal hydride alloys offer an economical alternative to traditional mechanical compressors for GH2. The simplicity and passive operation of the hydride compression process offers many advantages over mechanical compressors. Hydride compressors are compact, silent, do not have dynamic seals, require very little maintenance, and can operate unattended for long periods. However, they are a very new and may be difficult to be built at the scale required for GH2 transmission pipeline service. 

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