The "B" type uses the same basic core as the "A" type, but has only one removable head. Again both sides in spiral - true counter flow patterns. It is used then only one fluid is fouling. The other side is most often the service side with cooling tower water or steam. Elanco has done a lot of work with cooling tower water, and has developed velocity - temperature - pressure drop standards for SHE use when mechanical cleaning is not an option. By using high velocity in the channels, the cooling tower water will not foul the prime surface by more than f+.0005, for stainless steel. Annual descaling returns unit to new and clean, and is accomplished with a chemical descaler. The "B" type is substantially less costly to produce than an "A" type.