How-to: Select a Booster Set for Irrigation

Sizing booster systems for irrigation requires careful consideration in order to achieve optimum performance, efficiency and long-term reliability. So what are the main factors and requirements to take into account? We’ve put together this handy guide to help you understand how to choose the right pumps for your specific site and needs.

Pump Sizing - Head and Flow

Head and flow are the main requirements for any system.

The head is the highest point of discharge from a pump, but we need to understand the total amount of static head and other head losses in the system to define the total head. Pipework costs may push installers towards using less costly small-bore mains to the discharge points, only to undermine the long-term energy cost and system performance. 

Unfortunately, the friction loss within a small-bore irrigation system will demand more energy, escalating the running costs for energy. With this in mind, the more flow, the larger the bore pipework required, especially for the main distribution pipework. Other losses are found in any pipework system and should be accounted for when calculating the total head. Sprinklers, irrigators, fittings and valves will have an identified head loss value and that can be reduced by selecting the most appropriate ancillaries for your application.

Once the total head and flow has been determined, the process of selecting the pumping system can begin. Most facilities such as golf clubs, sports grounds, parks and large gardens will require a system using 2 or more pumps, with a ‘jockey’ pump to cope with small fluctuations in pressure demands.

Pump Control Systems

Booster set pumps are controlled by an electrical control system that monitors the pressure with the discharge water main and will start the pumps as demand increases. One pump may be required initially, but as demand increases an additional pump will be deployed to maintain a constant boosting pressure.

In some cases, the control systems may be as simple as mechanical pressure switches that activates a motor via ‘direct online’ starting methods. More commonly variable speed drives are being used to match performance with demand, giving better overall performance and long-term economy.

A reliable and efficient control system will have a myriad of additional built-in protection features supplementary to the expected motor overload protection. Dry running protection is essential to avoid damaging the pumps due to a lack of incoming water. Equally, pressure protection may be provided to shut the system down if there is a delivery main burst or an unplanned discharge.

Power Supply

Power supply is a critical consideration. There must be ample supply to meet the system's demands. Additionally, the location of the system is important; you should aim to strike a balance by optimising the pump set's placement for efficient irrigation while keeping it reasonably close to the main power supply. This will help to avoid increased costs associated with larger power cabling and prevent voltage drops that could undermine the system's performance.
 
 

Case Studies: Booster Sets for Irrigation

Hertfordshire Golf Course

As part of a wider water management scheme on a Hertfordshire golf course, a booster set meeting very high industry standards was needed in order to improve the distribution of water around the expansive course where the water was extracted from a lake.

A Dual Booster Set was sized and selected, complete with 2 x 5.5kW vertical multistage pumps, motor-mounted variable speed drives and a bespoke control panel to Irritech specification, including a backup fail-safe system via Digital Pressure Controllers. The pump, when set in a duty/assist configuration, will achieve a performance of 20m³/hr at 8.8 bar pressure.

Stoke City FC

This booster set is used daily to water the main football pitch at the bet365 stadium in Staffordshire.

The home of Stoke City FC requires watering daily to keep the pitch in premium condition, so they were searching for an efficient and economic product that could provide reliable irrigation with automatic control.  The system, which comprised of fixed and variable speed clean water multistage pumps, was designed and manufactured to provide both the flow and water pressure required to reliably cover the football ground.