Our Pumps | Is an “Air Gap” a Good Thing?

Understanding Air Gaps and Mechanical Seals

The first generation of rotary lobe pumps all had an air gap separating the wet end from the gear housing. Sludge and slurries are not suitable to be used to cool the mechanical seals because they contain abrasives and, sometimes, corrosives. Consequently, “air gap” pumps require separate water flush systems to permit limited dry running and to cool the mechanical seals. If “air gap” pumps are run dry the mechanical seal is destroyed.

To overcome these disadvantages, the second generation of rotary lobe pumps were designed with a separate oil quench chamber where the mechanical seals are bathed in oil. This eliminates the need to have a water flush system, keeps the seals cool, and thus permits dry running. The quench chamber is in place of the air gap found on the old style, first generation pumps.

LobePro pumps use the second generation quench chamber in their design, which allows the seals to run in an oil cooled chamber thus permitting the pump to run dry while providing much better lubrication than a water flush system. The stated advantage of having an air gap is to prevent the process fluid from contaminating the gear housing. However, in LobePro pumps, the gear housing is separated from the oil quench chamber by a double lip seal. While it is possible for the process fluid to make its way to the gear housing, it is very rare.

LobePro Mechanical Cartridge Seals

Our standard mechanical seals use Duronit vs. Duronit sealing surfaces. Duronit is a superior material for impact/ shock resistance and vibration and has wear characteristics are similar to Tungsten Carbide. LobePro electroless nickel or 316 stainless steel mechanical seals are assembled in the USA at our Brunswick, Georgia manufacturing plant. LobePro mechanical seal housings are corrosion resistant.

All LobePro mechanical seals are extensively tested before shipping. Seals are tested before and after pump assembly. Seals are tested at the intended operating pressure before shipping.