Pricing Environmental Health Risks: Survey Assessments of Risk - Risk and Risk Dollar Tradeoffs

An improved liquid ring pump includes an impeller having a larger axial length to diameter ratio than found in the prior art, with suction ports at both ends of the impeller. The number of impeller blades is chosen to be a prime number, preferably thirteen, to reduce pump noise and vibration. The pump housing includes novel manifolding for parallel or compound pump arrangements having two impellers, with suction ports at both ends of at least one impeller. A unique joint configuration between housing sections is also disclosed.