Pressure vs flow rate: what do these tell us about pressure washers
When considering a pressure washer for high-pressure cleaning, it's essential to delve into the specifications that truly define its cleaning performance. Two critical factors to keep in mind are pressure and flow rate. This article aims to clarify the meanings of pressure and flow rate, emphasising their significance in the realm of high-pressure cleaning.
Pressure: The Driving Force
Pressure, in the context of a pressure washer, represents the force exerted on dirt, grime, and mud. Simply put, the higher the pressure, the more powerful the cleaning capability of the pressure washer. However, there's more to pressure than sheer force.
Understanding Pressure (in theory):
Pressure is fundamentally a measure of force over an area, expressed by the equation P = F / A. While specifications often use BAR, visualising pressure in Pounds per Square Inch (PSI) makes it more tangible. For instance, if a 1lb weight is laid atop of a 1-inch cube, the pressure on the cube is 1 PSI.
Increasing pressure involves either enhancing the force or reducing the area. This practical insight helps us grasp the theoretical foundation behind pressure washers.
Pressure in the Practical World of Pressure Washers:
Pressure washers embody the mathematical principles of pressure. The force a pressure washer generates depends on the pump and motor. A more potent pump and motor allow for increased force by pulling more water through. The nozzle at the lance's end determines the area across which the force is applied. Larger nozzles reduce pressure by spreading force over a larger area.
Maximum Pressure:
Similar to overclocking a computer, using a smaller nozzle can exceed the recommended operating pressure. This tactic reduces the area, increasing pressure. Caution is necessary to avoid safety concerns and potential damage to the pressure washer.
Why Pressure Matters:
Pressure is a critical indicator of a pressure washer's ability to break up dirt. Higher pressure means greater force, surpassing the dirt's resistance. Exceeding this resistance accelerates dirt removal, making higher pressure crucial for effective cleaning.
Flow Rate: The Volume of Water Dispensed
The flow rate of a pressure washer refers to the amount of water it dispenses over time. In the case of our product specifications this is typically expressed in Litres per hour or Litres per Minute. Water flow is integral to cleaning efficiency and is closely tied to pressure.
Interconnection of Flow Rate and Pressure:
Pressure washers pull water at an accelerated rate to generate force. The flow rate and pressure are interlinked, with controls that reduce pressure also reducing flow rate. This relationship allows for variable pressure on some machines, adjusting both pressure and flow rate simultaneously.
Why Flow Rate Matters:
Flow rates are crucial for multiple reasons, including the water inlet supply. Larger machines may require breaker tanks due to their higher water consumption. In terms of cleaning performance, higher flow rates lead to wider and more efficient cleaning spans, reducing the need for multiple passes.
Link Between Flow Rate and Pressure:
Reducing the nozzle size or lowering the flow rate both result in increased pressure. This link is exemplified in pressure washers like the Ehrle HSC range, which offers variable flow rate/discharge capacity.
Conclusion:
Understanding the dynamic relationship between pressure and flow rate is paramount for making informed decisions when selecting a pressure washer. These specifications not only define cleaning performance but also influence the machine's versatility and efficiency in various cleaning scenarios.