While
these models physically look similar to the single-stage, they have been internally
designed to operate more efficiently, which in turn allows greater pressure
and vacuum. They are often used in preference to the rotary lobe type design,
due to the many advantages they offer such as; low noise, no lubrication/gearbox,
no pulsation and no maintenance. Absorbed power is improved compared to single-stage
models and pressure/vacuum can reach 750 mbarG / 550 mbarA.
