Water Meters
sdg.corrie
2014-05-15 08:53
Thank you for your concern with regarding the the Y-axis of the P&P graph, labelled as KL/H.
The height of the bar graph of each metering period (half-hourly intervals) is the average flow-rate for that metering period. The flow-rate is measured in kilo-litres per hour (KL/H). If you therefore want to know how many litres were consumed in any half-hour, you simply need to multiply the average flow rate (in KL/H) by the time in hours (0.5) and this will be your answer. (Half the height of the bar graph in KL/H, with KL units.)
You may feel that this is counter-intuitive, rather wanting the Y-axis to be in absolute litres. However, plumbers and plant engineers will typically know what the water consumption of a plant should be, and pumps are also rated in flow rate. On a graph like the one in P&P, an average flow rate that is too high or low is what would indicate a problem, and it would normally make more sense to display average flow rate than absolute amount of litres.
The fact that the metering period is 0.5h is a rather arbitrary choice by the Energy Supplier(ESKOM); from an engineering standpoint they could just as well have chosen 0.25h or 1h. And we stick to 0.5h for water as this is the standard on electricity time of use.
You can also reference this to the electricity graphs. Rather than displaying the absolute energy in kWh consumed in 0.5hour, P&P rather displays the average power consumed over 0.5h, in kW. If a plant engineer therefore run a 1MW motor for 0.5h, he will see a graph with a height of 1MW (=1000kW); rather than 500kWh, so he can relate the readings more intuitively with his plant rating, similar to relating the flow rate to the size of pipes and pumps and consumption of a building.
If you need the absolute litres consumed, (or kWh consumed) you can of course just run a provisional bill over the period of interest, which will then give you the required result.
I hope this explains the reason behind the choice of KL/H on the water graphs, please let me know if anything is unclear or if you have any special requirements.