Water Ring Vacuum Pump Scaling Causing High Power Consumption? 4 Ways to Remove and Prevent Scale

 Water Ring Vacuum Pump Scaling Causing High Power Consumption? 4 Ways to Remove and Prevent Scale

Water ring vacuum pumps are widely used in chemical processing, pharmaceuticals, paper manufacturing, food processing, vacuum filtration, vacuum dewatering, and industrial gas-handling systems.

After operating for a period of time, some users encounter a common problem:

The motor current gradually increases, power consumption rises, while vacuum performance begins to decline.

In more serious cases, the pump may also develop higher noise, vibration, overheating, or even difficulty starting.

When the motor and bearings appear normal, one possible cause deserves particular attention:

Scale buildup inside the water ring vacuum pump.

This problem is especially common when hard water or untreated circulating water is used as the working liquid.

So why does scaling increase pump power consumption, and how can it be removed and prevented?

Why Does a Water Ring Vacuum Pump Develop Scale?

A water ring vacuum pump uses a rotating impeller and working liquid to create the vacuum.

As the impeller rotates eccentrically inside the casing, centrifugal force forms a rotating liquid ring. The changing volume between the impeller blades and the liquid ring produces the suction, compression, and discharge process.

This means that the working liquid is an essential part of the vacuum-generation process.

If the water contains calcium, magnesium, and other scale-forming minerals, deposits may gradually accumulate on internal components during long-term operation.

Common scaling locations include:

Impeller surfaces;

Pump casing;

Distribution plates;

Working-liquid passages;

Circulation piping.

Higher working-liquid temperature, poor water quality, and repeated concentration of circulating water can accelerate this process.

Why Can Scaling Increase Motor Current and Power Consumption?

Scale does more than make the inside of the pump dirty. It can directly affect hydraulic and mechanical operating conditions.

1. Increased Internal Resistance

Deposits on the impeller and internal surfaces change the original flow conditions.

The impeller must overcome additional resistance when rotating through the working liquid.

The motor therefore requires more torque to maintain operating speed.

One of the most obvious symptoms can be:

Higher motor current under the same operating conditions.

2. Reduced Internal Clearances

Water ring vacuum pumps rely on specific internal clearances.

Heavy scale buildup may reduce these clearances and, in severe cases, contribute to abnormal contact or increased friction between components.

This may result in higher current, vibration, noise, and difficulty starting.

3. Restricted Working-Liquid Passages

Scale can also accumulate inside working-liquid passages and circulation piping.

Restricted water flow may disturb the liquid ring and reduce vacuum performance.

Therefore, when a pump shows the combination of:

higher current + lower vacuum + increased noise or vibration,

internal scaling should be included in the troubleshooting process.

However, scaling is not the only possible cause of excessive power consumption. Excessive working-liquid flow, high discharge pressure, bearing problems, mechanical friction, and other faults should also be checked.

4 Ways to Remove and Prevent Scale

1. Use Circulation Cleaning for Light Scale

If scaling is still relatively light and the pump can operate normally, circulation cleaning may be considered.

A cleaning solution compatible with the pump materials can be circulated through the affected system to gradually soften or dissolve deposits.

After cleaning, the system should be thoroughly flushed.

One important warning:

Do not simply use a strong acid without checking material compatibility.

The cleaning agent must be compatible with the pump casing, impeller, seals, mechanical seal components, piping, and other wetted parts.

If the scale composition is unknown, identifying the deposit before selecting a cleaning method is preferable.

2. Disassemble and Clean Heavy Scale

If motor current has increased significantly, rotation resistance is abnormal, or circulation cleaning produces little improvement, continuing to operate the pump may cause further damage.

The pump should be safely shut down, electrically isolated, depressurized where applicable, and inspected according to the equipment maintenance procedure.

Important areas to check include:

Impeller;

Distribution plate;

Pump casing;

Working-liquid inlet;

Circulation passages;

Internal clearances.

Heavy deposits may require mechanical cleaning.

Care should be taken not to damage machined surfaces, impeller geometry, distribution plates, or critical clearances during scale removal.

3. Improve Working-Water Quality

Removing scale solves the immediate problem.

Improving water quality helps prevent it from returning.

If the available water has high hardness, appropriately treated make-up water may be considered according to the process and equipment requirements.

Circulating systems require additional attention.

As water evaporates during operation, some dissolved minerals remain in the circulating liquid. Their concentration may therefore gradually increase.

Over time, this can accelerate scale formation.

For this reason, operators should monitor not only the working-liquid level but also water quality and concentration trends.

Proper make-up and blowdown practices can help control mineral accumulation.

4. Control Working-Liquid Temperature and Circulation

Working-liquid temperature affects both scaling tendency and vacuum performance.

As water temperature increases, its vapor pressure also rises, which can reduce the achievable vacuum level of a water ring vacuum pump.

A properly designed circulation system should therefore maintain working-liquid temperature within the range required by the pump and process.

Depending on the application, this may involve:

Heat exchangers;

Cooling water;

Controlled make-up water;

Periodic blowdown;

Regular replacement of contaminated circulating liquid.

If circulating water is continuously reused without adequate treatment, minerals and contaminants may accumulate even after the pump has recently been cleaned.

Why Does Scale Return Soon After Cleaning?

If a pump is thoroughly descaled but the original operating conditions remain unchanged, scale can quickly develop again.

Repeated scaling should prompt four questions:

Is the make-up water too hard?

Is the circulating water being concentrated without sufficient blowdown?

Is the working-liquid temperature consistently too high?

Is the circulation and cooling system operating correctly?

If these root causes are not addressed, repeated chemical cleaning or disassembly only treats the symptom.

How Can You Detect Scaling Before the Pump Fails?

Routine operating data can provide useful early warning signs.

Consider monitoring trends in:

Motor current;

Inlet vacuum level;

Working-liquid temperature;

Working-liquid flow;

Noise;

Vibration.

For example, if the motor historically operated at a stable current but the current gradually increases while vacuum performance declines under similar process conditions, inspection should be considered.

Trend monitoring can help identify developing problems before they cause an unexpected shutdown.

Conclusion

Scaling inside a water ring vacuum pump can increase operating resistance, raise motor current and power consumption, reduce vacuum performance, and in severe cases contribute to abnormal friction or starting problems.

Four practical strategies can help:

1. Light scale — use an appropriate circulation cleaning method.

2. Heavy scale — shut down and inspect or clean the pump.

3. Repeated scaling — improve working-water quality.

4. Long-term prevention — control temperature, circulation, make-up water, and blowdown.

Most importantly, do not assume that every high-current problem is caused by scale.

Motor current, vacuum level, working-liquid flow, temperature, mechanical resistance, and operating conditions should be evaluated together.

Regular cleaning can remove scale, but controlling water quality and operating conditions is what helps prevent it from coming back.