Those in the industry already know that pressure and flow are two key elements that help deliver fast and effective cleaning services. However, understanding how pressure and flow work together, and what each contributes to the cleaning process, is often overlooked. By taking the time to develop this knowledge, owners and operators will be equipped to find the best cleaning equipment for their operations.
Before considering how to measure the effectiveness of a machine, it is important to understand what pressure, flow, and cleaning units refer to.
Pressure: Pressure is measured in bar (pascals) – and measures the force at which the water hits the asset. In terms of pressure cleaning, this high force is targeted to a smaller area, blasting the surface clean.
Flow: Flow is measured in litres – and refers to the total capacity for liquid output from the machine. In pressure cleaning, this large volume of water removes grime and rinses large surface areas.
Cleaning units: Cleaning units (CU) are a measure that can help buyers understand the efficiency of the machine; they allow a comparison to be made between different machines. The CU number is found by multiplying the two important factors already mentioned: bar and LPM (litres per minute). Buyers will be able to make an informed choice once they develop an understanding of how different combinations of the two values work together.
The effectiveness of a machine can be influenced by so many variables that at first glance one might wonder how any comparisons can be made. To combat this, the first step is to simplify the parameters by sticking to a set of assumptions and set the scope of the evaluation. The second step is to note that there will be a time to start considering the other factors that contribute to the cleaning process.
The key assumptions help evaluate the machine at its most basic level; the assumptions made should be that:
The scope for evaluation includes measurable figures:
These are the impacts that you may consider down the line, once you have some good machine options picked out:
One of the reasons it’s important to understand the pascals (Pa) and LPM, and not just rely on the CU as the source of truth, is because similar cleaning units may result from different combinations of pascals (Pa) and LPM, each with a unique result.
A low pressure, high flow machine with 2000 pascals (Pa) and 4.0 LPM results in 8000 CU. A high pressure, low flow machine with 4000 pascals (Pa) and 2.0 LPM also results in 8000 CU. With the same cleaning units, do they perform the exact same? Not necessarily, the rinsing power of the low pressure, high flow machine will cover a larger area, which means that dirt be removed faster even though both pressure washers have the same CU.
We can compare this to the real-life example comparing a fire hose and a high-pressure hose at a car wash. A fire hose, which delivers a high flow of water at low pressure, covers a large surface area, and even has the power to force its way through a wall. Now consider the high-pressure hose at the car wash. It delivers a much lower flow rate; it still has the pressure to remove dirt and grime, but over a much smaller area with lower overall impact.
So why has the market seen a push towards higher pressure equipment over the years? It’s a combination of factors.
It’s simple human psychology to connect higher power with better results; bigger is better. This is amplified when a buyer is only focused on the pascals (Pa) rather than considering the combination of factors that determine a machine’s efficiency. With the development of technology, there is also an excitement that comes with owning the newest machines capable the highest pressures.
A water delivery system’s flow rate limitations may also see buyers looking for a high-pressure option to balance out the machine’s cleaning power. From a purely practical perspective, the only situation in which the advance plumbing needed to support an extremely high flow system would be installed in a permanent in-plant system, which is certainly not economical or functional for mobile operators or smaller businesses.
Finally, there is the environmental cost. In a world that is focusing more on ethical resource use and sustainability, owners must consider the drain on water resources and the further reaching impacts. This may include acquisition and disposal costs, the restrictions placed by state and federal governments, the requirements stipulated by councils and utilities to be eligible to submit a tender, and more.
Developing your understanding of the interplay of pressure and flow rate is a great starting point. After this, buyers can start considering how different water temperatures or the use of chemicals may contribute to improving the efficiency and effectiveness of the machines. This is the ideal time to speak with a reliable supplier. With a wealth of knowledge behind them, your supplier will be able to advise (and even demonstrate) the capabilities of the systems being considered, as well as building operator skill by offering guidance on their use.
The future of the industry is bright. Pressure cleaning equipment will continue to grow, develop, and improve in response to the needs of customers, operators, competitors, suppliers, and regulators. Walking in armed with an understanding of pressure and flow rate puts the power in your hands.”
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