1st, highest attained vacuum highly (4.5 - 14mmhg) 2nd, does not have the oil lubrication, may
attain the pure vacuum 3rd, the WLWF series uses the stainless steel or the lining fluorine, the
titanium material, ability each kind of acid, the alkali, the organic solvent corrosion. 4th,
the energy conservation (3,3%0, saves water (50%), saves area 966%). 5th, the air valve axial
installment, the service life is long (4=10 to double). 6th, vibrates slightly, the noise is
low. 7th, contour succinct artistic, the operation, the service is convenient.