Liquid Ring Vacuum Pumps: From Norwegian Fisheries to Food Packaging Excellence

Norway has a long tradition of catching and processing fish, ranking second globally in seafood exports. Ensuring the quality of freshly caught products from vessel to consumer demands reliable vacuum packaging at industrial scale — and one of the core technologies powering those packaging lines is the liquid ring vacuum pump.

Why Fisheries Choose Liquid Ring Vacuum Pumps

The operating principle of liquid ring vacuum pumps gives them unique advantages in food packaging:

• Water is the working fluid — no metal-to-metal contact inside the pump, only the rotor interacting with the liquid ring. This means: oil-free operation, no contact wear, low operating temperature
• Handles moisture and vapor-laden gas streams naturally — in fish processing environments, water vapor and liquid carryover are constant challenges. Liquid ring pumps handle these natively. Oil-sealed pumps, by contrast, require complex condensation traps and gas ballast systems to prevent moisture contamination of the pump oil
• Near-isothermal compression — the liquid ring serves as a continuous cooling medium, absorbing compression heat in real time. Exhaust temperatures remain close to isothermal — critical for packaging heat-sensitive food products
• Stable operation, simple maintenance — no complex internal valves, no contacting seals. Primary maintenance consists of regular water changes and mechanical seal inspection

How a Liquid Ring Vacuum Pump Works

The pump body contains a set volume of working fluid (typically water). An eccentrically mounted impeller rotates, and centrifugal force drives the liquid against the inner pump wall, forming a liquid ring. The spaces between impeller blades are sealed by this liquid ring. As the impeller rotates, the volume of each sealed cell first increases (suction), then decreases (compression and discharge).

The elegance of this design: the liquid ring simultaneously performs sealing, cooling, and compression — three functions in one component, with remarkably simple construction.

Beyond Fisheries: Broad Industrial Applications

• Food packaging: vacuum packing, modified atmosphere packaging (MAP), thermoforming machine vacuum systems
• Pulp and paper: paper machine vacuum dewatering, suction boxes
• Chemical and pharmaceutical: solvent recovery, distillation, drying — the ability to handle condensable vapors makes liquid ring pumps irreplaceable in these processes
• Medical: hospital central vacuum systems — near-isothermal operation and oil-free design make liquid ring pumps the safe choice for medical vacuum
• Plastics processing: vacuum forming, extrusion degassing

Liquid Ring vs. Other Vacuum Technologies

Liquid ring pumps cannot match the ultimate vacuum of oil-sealed or dry pumps. But in food packaging, pulp and paper, and chemical processing — applications where “good enough, tough enough” matters more than extreme vacuum — the liquid ring pump’s low maintenance, high reliability, and natural water vapor tolerance make it the most cost-effective choice.

Doskee Automation specializes in industrial automation and fluid control, offering liquid ring vacuum pumps, rotary vane pumps, dry screw pumps, and complete vacuum system products. We recommend the optimal vacuum solution based on your specific process requirements. For technical consultation, please contact us.

References: PneumaticTips “Norwegian fisheries rely on liquid ring vacuum pumps for packaging” | Atlas Copco / Nash Liquid Ring Pump Technology Guide