Liquid Ring Vacuum Pump Descaling

Liquid ring vacuum pumps are used across a wide variety of industries. Over time, the pump inside the machine will accumulate scale build-up in the form of calcium, lime, dirt, and rust. Scale build-up can reduce the efficiency of the liquid ring vacuum pump and cause severe damage over time.

What is a Liquid Ring Vacuum Pump?

Liquid ring vacuum pumps are rotating positive displacement machines that provide process vacuum to a range of industries. They are used to evacuate or compress gas to atmospheric pressure. A rotating vane impeller, located eccentrically within the cylindrical casing, compresses the gas.

Water, or another compatible liquid, is fed into the pump, forming a moving cylindrical ring against the inside of the cylindrical casing. The moving liquid ring creates seals in the space between impeller vanes, forming compression chambers. Once gas is fed into the pump, a cyclic variation of the volume enclosed by the vanes and the liquid ring occurs.

Liquid Vacuum Pump Descaling Solution

Our recommended descaler for liquid ring vacuum pumps depends on what the internal parts consist of.

  • Dynamic Descaler: We recommend using our Dynamic Descaler for pumps that contain internal parts made up of steel.
  • Platinum Descaler & Descale 518: Use our Platinum Descaler or Descale 518 for pumps that contain internal parts made up of stainless steel.
  • Aqua Safe Descaler: Our Aqua Safe Descaler is potable water appproved and UL certified NSF/ANSI 60. This Descaler has excellent results for liquid ring vacuum pumps used in a marine setting, like priming systems.
  • Aluminum Descaler: Our Aluminum Descaler has no effect on 7075 and 6061 aluminum dyes and cast bolding. We recommend using if your liquid ring vacuum pump contains aluminum.
  • Citric Descaler: The solution for our Citric Descaler is citric-based and is a green product. It’s environmentally-safe and effective on most metals, making it a favorite for water-cooled equipment.

For any questions about which descaler to use, email us at or call us at 1-800-388-5818.

See our Descaler in Action

Liquid Vacuum Pump Descaling Instructions

Follow these instructions to remove water scale, lime, mud, and rust from the casting, rotor, hub, cones, and associated piping of your equipment.

1. Write down the “before “amp readings, cfm at vacuum capacity, and the vacuum in inches of mercury.

2. Take the pump out of service.

3. Insert “blanks” in flanges of discharge and suction piping.

4. Remove the bottom drain plug and allow all water to drain from the pump casing. Place plug with a 1” PVC ball valve with a 1” male poly PVC cam lock fitting.

5. Remove top plug and add a 1” PVC ball valve with a 1” male poly PVC cam lock fitting.

6. Get a circulating pump and circulating tank. The pump should be a chemical magnetic or double diaphragm constructed of poly with the inlet and outlet fitted with a 1” PVC ball valve with a 1” male poly cam lock fitting. The circulating tank should be constructed of a poly or plastic with an in and out fitting with a 1” PVC ball valve with a 1” male poly cam lock fitting.

7. Get three 1” chemical hoses. The length should be determined by each position of the vacuum pump and the circulating tank. The hoses should have 1” female poly cam lock fittings.

8. See below diagram for set up.

9. Fill the circulation tank with water. Turn on the circulation pump and open the valves to get the circulation back into the circulating tank.

10. Circulate water into the vacuum pump to test for leaks. If no leaks, drain water from the vacuum pump.

11. With no leaks, you are ready to circulate the Descaler into the vacuum pump. Fill the circulating tank with our Descaler. Turn on the circulating pump and open all valves. Add the prescribed amount of Descaler into the circulating loop. In some instances, water may be required to maintain circulation.

12. After 30 minutes of Descaler circulation, turn the pump rotor 90 degrees by pulling on the drive belts.

13. Every 30 minutes thereafter, turn the rotor 90 degrees to assure a thorough cleaning of the interior part of the pump, including the hub and rotor.

14. After several hours of circulation, with intermittent turning of the rotor, the pump should be clean and the rotor should turn freely.

15. Shut off the circulating pump and add fresh water to the circulation container.

16. Restart the circulating pump and flush until water runs clear.

17. Check the pH of the Descaler to see if it is neutralized.

18. Disconnect the return hose and run to the drain.

19. Disconnect pump and all hoses. Remove all the blanks and flanges and reconnect all piping.

20. Open seal water valve. With the bottom valve open on the vacuum, flush the vacuum pump with seal water for about 45 minutes.

21. Return pump to service.

22. After the vacuum pump has stabilized, write down the “after” amp reading, cfm at vacuum capacity and vacuum in inches of mercury.