Bio gas blowers, based on Positive Displacement Rotary Air Blower principle, have been specially developed for pumping of biogas. These gas blowers are generally used in biogas lines to boost the gas pressures to meet the burner input demand. These gas blowers are generally vertical in construction, that is suction top and discharge bottom, so as to prevent any accumulation of corrosive matter inside the casing. Since they operate in closed loop, suction and discharge silencers are generally not required. Special material of construction, lubrication and sealing arrangements make them ideal choice for biogas applications.