Deragging pumps - preventive and predictive maintenance

Q: What is the difference between proactive and condition-based deragging?

In the Danfoss drive, deragging is a built-in feature . It reverses the impeller rotation repeatedly, to create a clear path for the flow of water. In proactive deragging mode, the drive constantly monitors and proactively declogs pumps. This enables the system to achieve optimal efficiency with virtually no downtime, and energy savings of up to 50%. In condition-based deragging mode, the drive senses the beginning of a pump clog. It enters washing mode by reversing the pump spin to ensure a clear path for the water. As a preventive action, the drive can be set up to reverse the pump at set intervals for regular self-maintenance. Water distribution and wastewater treatment facilities benefit significantly from the inbuilt deragging function. This function performs impeller washing cycles to extend manual maintenance intervals, while keeping up pump efficiency and extending pump lifetime.

Derag pumps for more uptime

Clogged pumps work less efficiently and use more energy to do their job than clean pumps. If unattended, eventually a clogged pump will grind to a halt, causing unplanned downtime. Therefore, it is unsurprising to find that pump clogging is a costly issue for sewerage systems and wastewater treatment plants. The solution? Deragging functionality in the AC drive can prevent clogged pumps, promote uptime, and cut operating costs.

Prevent clogged pumps with condition monitoring and deragging

There is no need to experience a clogged pump ever again. With the help of intelligent variable frequency drives, it is possible to detect potential clogs early. When detected early enough, operators can derag and clear the debris causing blockage, before it affects the electricity bill or causes downtime. Since the functionality is integrated in the drive, operators achieve reduced installation time. Even more significantly, improved predictive maintenance lowers operating costs and boosts uptime for the wastewater industry.

How does condition-based deragging work?

The technology behind early clog detection and deragging is integrated into intelligent drives from Danfoss. Condition-based monitoring and the deragging functionality act together to support reliable and hassle-free pumping. The combined effect of condition monitoring and deragging is also known as condition-based deragging.

Potential pump clogging is visible in the pump load profile, already at the early stage of partial clogging. Using integrated condition-based monitoring (CBM) the drive raises an alert, giving operators the power to intervene, also known as human-in-the-loop machine learning.

Play the video to learn how the integrated deragging functionality reduces your installation and running costs.

Real-time monitoring detects pump blockage

How does the integrated CBM functionality know when a deviation from correct pump operation arises? Cloud-free machine learning embedded in the drive automatically defines operating baseline parameters corresponding to specific applications, at all speeds and real-life operating cycles. Once the baseline is defined and the learning period completed. CBM can detect deviations. Over time, once operators learn how often blockages occur, they can set the deragging function to operate at optimal intervals. Regular deragging intervals are a valuable contribution to the preventive maintenance strategy for pump maintenance.

Condition-based deragging

During operation, the energy monitoring system detects when pumping consumes more energy than it should. When this happens, the pump is already beginning to clog, which can be prevented by deragging. The VLT^® AQUA Drive with integrated deragging functionality initiates a condition-based cleaning cycle for pump preventive maintenance.

Discover VLT® AQUA Drive

The cleaning pattern

The integrated deragging feature of the VLT® AQUA Drive cleans the impeller by cyclic operation of the pump in both directions. The user can specify how often, how fast and how long the impeller rotates in forward and reverse directions, for pump preventive maintenance. Not every type of pump can run in reverse. Consult the pump manufacturer before using this function.

Read the deragging fact sheet

Clog-free pumping since 2021

Grand Strand Sewer Authority has 769 pumping stations and is adding new ones on a regular basis, so clogging is a significant concern. However since implementing deragging in May 2021, the Authority has experienced no need for manual cleaning or unclogging of its pump systems.

Learn more

How does CBM optimize pumping?

Take motor and pump supervision to new levels with VLT® AQUA Drive. This video explains how CBM empowers you to act quicky to counteract the effects of clogs, leaks, vibration, and other issues, as part of your predictive maintenance strategy.

FAQ

Why do flushable wipes clog sewer systems?

The most common blockages caused by flushable wipes happen in two ways. First, the disposable wipes get caught on a pump impeller and cause a build-up which eventually clogs the pump. This causes the impeller to stop rotating, resulting in downtime. This kind of clogging can be prevented using intelligent drives with integrated condition-based monitoring and deragging functionalities to control the pump motor.
Second, the sewer pipes can become blocked with accumulated fat and debris – including flushable wipes – causing fatbergs. Preventing pump clogs can help operators to act early to avert buildup of this kind of debris in sewer pipes.

How can I avoid clogged pumps?

Avoid downtime and costly maintenance due to clogged pumps. Apply variable speed control to the pumps with intelligent drives from Danfoss. The integrated CBM and deragging functionality of the intelligent drives can operate cloud-free using edge computing.

What happens when a pump clogs?

Clogged impellers in wastewater pumps can be a permanent and serious problem. Over time, fibers and particles will build up on the impeller vanes, leading to poor efficiency and extensive wear of the pump, even pump failure. Clogging reduces the capacity of the pump and increases the risk of pump blockage. That’s why clogs can result in pump downtime for maintenance and ultimately a shorter pump lifetime expectancy.

Manually cleaning the pump is time consuming, as maintenance staff must travel to the site to lift, clean and reinstall the pump; a process that often needs special equipment. A better solution is to avert clogs by implementing variable speed pump control using intelligent drives. These drives are equipped from the factory with integrated condition monitoring and deragging functionality.

What is the difference between proactive and condition-based deragging?

In the Danfoss drive, deragging is a built-in feature. It reverses the impeller rotation repeatedly, to create a clear path for the flow of water. In proactive deragging mode, the drive constantly monitors and proactively declogs pumps. This enables the system to achieve optimal efficiency with virtually no downtime, and energy savings of up to 50%.

In condition-based deragging mode, the drive senses the beginning of a pump clog. It enters washing mode by reversing the pump spin to ensure a clear path for the water. As a preventive action, the drive can be set up to reverse the pump at set intervals for regular self-maintenance.

Water distribution and wastewater treatment facilities benefit significantly from the inbuilt deragging function. This function performs impeller washing cycles to extend manual maintenance intervals, while keeping up pump efficiency and extending pump lifetime.

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