Under-pressure pump system now under control

Kelair Pumps Australia were contacted by a local council in Mackay who were experiencing an issue with a Grundfos pump set, used to supply Class A recycled water for irrigation of the town’s vast green spaces including sports fields, school grounds as well as the local golf course.

In service now for over a decade, the pump system, comprising of five CR64-4-2 Vertical Multistage pumps, had already received several replacement motors in the past, but it now required a new smart pump controller in order for the pumps to run as an automatic pressure-controlled system. This meant the system would maintain a constant pressure throughout the network and ensure the irrigation system was not subject to large pressure and flow peaks, an issue that had been causing the council a great deal of service and maintenance issues.

The failed pump set controller, as well as only being able to operate three out of the five pumps in manual mode without pressure control, had a flow on effect with several major issues developing within the network as a result:

• Any significant flow requirements within the recycled water network caused a severe amount of water hammer resulting in failure of various sprinklers throughout their irrigation network.
• With only three pumps able to operate they were well below the network requirement of the end users.

A cost-effective solution

Looking for a cost effective, fit-for-purpose solution, the council approached several reputable, well-established pump service providers around the region, including Kelair Pumps.

Kelair found that replacing just two of the motor/drive units alone represented two thirds of the total cost of replacing the entire system. Furthermore, continuing to run the other three existing motors without replacement also posed a significant risk of future failure. Kelair suggested that the most economical and practical solution was to completely overhaul the entire system and convert it to standard motors controlled by Hydrovars’.

According to Kelair Pumps' Sales Engineer, Hydrovar units were the perfect solution as they did not require a dedicated pump controller for the system to function as intended. “The Hydrovars’ are designed to be able to communicate with up to eight drives without the need for a dedicated controller as all the settings and pump control functions are handled locally inside the unit. In this case, we solely used master versions meaning the remaining pumps would continue to operate normally in the event one of the Hydrovars’ or standard off-the-shelf motors suffered a mechanical failure”.

Of further benefit, Hydrovar units can be retrofitted to any brand of pump which was hugely significant in this case as it meant the existing Grundfos pumps did not need to be replaced and costs were kept down.

And should a motor unit need to be replaced again in the future, it’s a simple fix. “As the Hydrovars’ do not require a proprietary motor the council could source a suitable motor from their regular electrical wholesaler or contractor. They would simply unmount the Hydrovar and remove the failed motor”, the sales engineer said.

Kelair commences work

After evaluating all submissions, the council accepted the proposal presented by Kelair and the team in Mackay were engaged to complete the work. Impressively, the five new Hydrovars along with the five new motors arrived within the week, with work to replace the existing system scheduled to occur only ten days after receiving the order from the council. Once the council had communicated with all major stakeholders utilising the recycled water network, Kelair were given a 48-hour window where the pumps would be offline and the new motors and Hydrovar controllers would be installed.

Kelair coordinated with a local electrical contractor to ensure disconnection and isolation of the electrical components of the existing pump set and control panel. Upon arrival at the site, the Kelair team completed all relevant safety documentation required for the council and by the end of the day, had removed all unnecessary components, upgraded the distribution panel and, installed the new motors and Hydrovar controllers to the existing Grundfos vertical multistage pumps.

By mid-morning the following day, the mechanical and electrical works had also been completed and the team were able to begin the programming of the Hydrovar controllers. “The integrated control pad and screen of the Hydrovar allowed full programming without additional equipment,” Kelair's Sales Engineer noted. This was all while mitigating any overtime being imposed onto the council operators, who were required to be on site at the Wastewater Treatment Plant for the duration the works were carried out.

Once the system was ready to be started the council arranged for all possible high points in the network to be opened, so any air that had entered the recycle water network was able to escape safely without causing injury to personnel or damage to infrastructure during the priming of the network.

Within two hours, over 10 kilometers of the network was filled, and system pressure was gradually increased to meet the council’s requirements.

By mid-afternoon, the system was fully operational working automatically as a pressure-controlled system ready for irrigation testing overnight by the end users and council parks and gardens.

A model for the future

Regular follow-ups revealed the council’s satisfaction with the system. According to the council’s Northern Team leader, the network now supplies 15-25% more effluent than it can produce daily. This has significantly reduced levels in the effluent storage dam, addressing concerns about potential overflow.

The council is so pleased with the solution that they are considering similar upgrades for other recycled water and potable water systems.

Kelair Pumps Australia

Since 1975, Kelair Pumps has specialised in providing pumps and pump packages for the diverse pump operations across Australia. If you require an engineered solution for your pumping needs, please contact your local Kelair Branch. You can rely on Kelair Pumps to provide the pump knowledge, service and expertise required.