N551B and N552B ? Drum top 55 gallon vacuum generating heads fit existing 55 gallon drums. Units are fitted with efficient vacuum venturis that operate off 3/4" air lines and generate high vacuum lift. Single venturi units consume 68 SCFM at 100 PSI and produce 185" waterlift; dual venturi units consume 110 SCFM at 100 PSI and 163" waterlift. Vacuum suction for the single venturi is 89 SCFM adn for the dual 163 SCFM. Optional items available include a liquid shut-off assembly for wet-dry applications, a 99.97% HEPA filter and an exhaust housing silencer to reduce dBa. Pictured here is the single venturi, N551B and the N552B is the dual venturi option available. Please contact us if a vacuum product of this nature is of interest and we can quote the vacuum lid assembly best suited to your application.