IAPMO updates water demand calculator


The International Association of Plumbing and Mechanical Officials (IAPMO) announced that the Water Demand Calculator (version 2.0) is now available for download.

The basic template of the calculator remains the same, however, there are several new features. This includes the addition of a drop-down menu that offers a selection between a single and multi-family building.

“The Water Demand Calculator has become more robust while remaining fast and user friendly,” said Dan Cole, IAPMO’s senior director of technical services. “Increasing the accuracy in predicting peak water demand for multifamily dwellings will lead to reductions in pipe sizing accompanied by increased cost savings.”

The multi-family option activates two additional input boxes that require the user to specify the total number of apartments that are in the building and in the calculation – the latter entry is linked to the probability of fixture use column in the calculator, gradually reducing the percentage as the number of apartments increases. This feature would provide predictions of peak water demand in large multi-family dwellings.

Additional computed information pertaining to the peak conditions is also available in the update. The calculator will give the average number of simultaneous busy fixtures in use at any instant during the peak period – called the Hunter Number – and the probability of no flow. In addition, it will provide the total fixture count and the 99th percentile demand flow.

A download button is provided for users who wish to save computed results in a notepad.


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