Quick Checks to Reduce Your Pumping Bill!
Pumps are an essential part of many industries, particularly for irrigation. While they can be automated to perform set schedules, they are not a ‘set and forget’ piece of equipment. They require regular upkeep to ensure they are working as efficiently as possible.
Ensuring that your pump is running optimally will provide energy and cost-saving benefits. As well as this, it can also result in reduced water wastage, which is particularly important for drought regions!
Benchmarking Your Pump
The best method for determining if your pump is underperforming is to measure the operation metrics (such as flow rate and pressure) and compare these to design expectations and industry benchmarks.
If your site has an existing water meter, this can be used to estimate water consumption. However, it is important to know that meters installed by the water utility companies are designed to under-read water usage over time so that customers are not overcharged. This will result in inaccuracies in the water meter readings.
The flow rate of the pump for each irrigation schedule is important for irrigation design. Measuring this requirement can be tedious, as it often involves accurate sprinkler counts. More sophisticated devices can streamline the process. At Websters Group, we use ultrasonic flow metering equipment to provide quick and accurate measurements of the flow rate straight out of the pump. This equipment is non-invasive and eliminates the need to count sprinklers.
In-line pressure gauges are useful for detecting pressure drops. A decrease in pressure between the suction and discharge side of a pump filter can indicate a number of issues (such as debris build up in the filters).
These metrics can be used to find a replacement unit or retrofit an existing unit.
Common Retrofit or Replacement Situation
A commonly found pump efficiency upgrade is the replacement of flow rate control devices (throttling valves). This method for reducing flow through the use of a throttling valve is energy inefficient as it does not decrease the energy required for the decreased flow. The same amount of energy is used to pump, however, more energy is lost through the valve, which results in the flow reduction. Bypassing is also an energy-inefficient method of decreasing flow to meet irrigation requirements. These methods are often used because they are simple and cheap to install and operate.
Comparably, a variable speed drive (VSD) is a device that adjusts the motor speed to meet the flow requirements. This device requires knowledge of irrigation design values and adjustments needed to be made to suit the flow rates for each plot. This method can result in big savings, particularly if the flow requirements vary from plot to plot. However, without accurate information, correct assessment and design cannot be performed.
If all irrigation requires the same flow, this is a good opportunity to investigate a pump downgrade to a smaller more efficient pump in some cases.
Case Study: Pump VSD Retrofit
An example of a site where a throttle valve was removed and retrofitted with a VSD is given below:
At a farm in Northern Queensland, it was found that an old pump was being used to irrigate several different plot configurations. This pump was not designed for the job and was drastically oversized. For this reason, the farm had to use a throttle valve to control the flow for the different schedules.
Flow rate measurement equipment was used to quickly determine the flow requirements for the various schedules. It was seen that one schedule required half the amount of flow as another schedule. As the farmer was throttling the pump, the energy draw was just as high in both scenarios.
The flow equipment allowed for the pump duty points to be obtained for the irrigation schedules. An assessment of these found a more appropriate pump with a VSD that resulted in energy savings of 16,500 kWh/year, or $4,400. This new irrigation setup is expected to pay for itself after just 5.4 years.
Quick wins for pumps can come from performing a few routine maintenance checks!
Below is a list of quick areas to investigate as part of these checks:
Review any leaks in pipework and repair these. An easy spot check for leaks could be reviewing areas between sprinklers where excess grass or weeds have grown.
Impeller and Housing
When was the last time a service technician checked impeller clearances in your pump? Impeller wear and damage can affect the operation of a pump.
Any excess noise or vibrations could indicate an internal issue with the pump and could also cause bolts and fittings to loosen over time. Check for signs of rust or erosion on the housing.
Seals and Bearings
Check the integrity of your seals and bearings. These can be impacted by excessive heat and debris build-up. Ensure the pump is housed in an appropriate area, is kept clean, and is appropriately lubricated.
If pumping is a high energy cost, it is worth seriously looking at potential upgrade options as well as maintenance actions.
Interested in benchmarking the performance of your pump? We can assist with remote assessment tools or perform an on-site assessment!