Technical News
Page 10
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Low down air drier
SAB TWIN-DRIER INSTALLATIONS
SAB-AUTOMOTIVE, of Newton. Aycliffe, Darlington, has developed a new drier for compressed air braking systems. SAB says it can easily be fitted to any such system on the market and that its horizontal mounting makes it particularly suitable for vehicles with low chassis.
The drier has two drying cartridges, both of which contain a high-absorption drying agent.
SAB's claim is that in its twin tower drier the normal life expectancy of desiccant material will be doubled to about two years.
Air from the compressor passes through a separator, a centrifugal filter to remove oil, and a desiccant bed to remove moisture, in the left-hand cartridge. A small proportion of clean, dry air then expands through a constriction and is blown back into the right-hand cartridge to regenerate its desiccant.
When the air receiver reaches maximum working pressure a pneumatic pulse shuts off the drier and pressure between the two cartridges is equalised. Then when the air pressure falls and the compressor cuts in again, the drier is pulsed again and this causes its drain valve to open and expel the moisture, oil or dirt accumulated in the separator and filter.
Air from the compressor is then routed through the righthand cartridge while the lefthand one is regenerated, and so the process continues.