The Perma Pure Baldwin Series Aerosol removal system is specifically designed for gas sample applications with relatively high SO3 content (>10ppm). The SO3 aerosol removal series has special timing circuits that alternate freeze and thaw the precisely packed heat exchangers. Before an active heat exchanger thaws, the alternate active heat exchanger reaches the -7C set point to ensure uninterrupted operation and no SO3 slippage. This subzero temperature forms a thin ice layer that captures and removes SO3 aerosol from the sample stream.