A Guide to Water Pressure / Water Flow
Tuesday, April 29th, 2014
Water Pressure / Water Flow
What is the difference between Water Flow and Water Pressure?
Water Flow:
The term ‘water flow’ is simply a means of measuring the amount of water which is expelled from a source (eg: a tap) over a pre-determined period of time. Exactly which period of time is used to measure flow depends on how much water is flowing, but for households, it is usually measured in the form of litres per second for the sake of simplicity and easy calculation.
Water Pressure:
The term is a means of measuring the amount of force with which water is expelled from a source (eg: a shower) as opposed to the volume of water (ie: the water flow). There is often an inverse relationship between water pressure and water flow. For example, if a tap’s faucet is only partially open, the water will come out at a higher pressure (with less overall water flow) as it is being condensed. Opening the faucet more will cause the water pressure to lessen, but increase the overall water flow by a significant margin.
Water pressure is considerably more difficult to measure than water flow in all but the vaguest of measurements. While you can usually tell if water is coming out at low or high pressure simply by looking at it but getting an accurate reading of the exact water pressure levels virtually impossible to do without specialist tools. These are particularly useful when having new water based appliances installed, repaired and replaced.
Here the main ways DeWAR Plumbers use to measure water flow and water pressure:
Measuring Water Flow:
Anyone can measure water flow in a rough fashion. To do this, all one needs is a ten-litre bucket and a watch:
- open the water source
- count how many seconds it takes to fill the bucket
- divide the time taken in seconds by ten
- now you have the water flow measured in litres per second
For a more accurate reading, you will need to use a device such as a water flow weir cup. This takes very accurate water flow measurements in both litres per second and also gallons per minute, allowing a plumber much more specific readings which are vital when installing appliances which use a particularly large flow of water such as combi boilers or high efficiency condensing boilers. If the water flow is deemed to be insufficient, then the water flow weir cup can be used to adjust it so that it can be used for the required task at hand based on the appliance’s manufacturer’s specifications.
Measuring Water Pressure:
This is the most commonly used means of gauging water pressure by a plumber. When the mains water gauge is attached to a water outlet it is then possible to read the levels of water pressure coming from the same outlet. This is usually measured by means of a series of bars which the plumber can then check in accordance with your appliances’ manufacturer’s specifications in order to ensure that they are operating at the correct level of water pressure.
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