Monitoring Water Hammer

Monitoring differential pressure is one of the most critical functions in any heat or plumbing network.

DP is required to make water flow, but too much will damage equipment.

One of the major problems with current BMS systems is there speed - they are far too slow to spot spikes in pressure. BMS systems typically report values every 15 minutes, so trying to understand an even that may last only 0.5s is impossible.

The flow below runs on a standard Heatweb open controller, and monitors differential pressures at 0.1s intervals. When pressure out of limits is detected, 50 consecutive readings (5 seconds worth) are emailed to engineers concerned for record and analysis, with the spike positioned in the middle of the data so we can see climb and fall in pressure.

When performing such fine detailed analysis it is important to manage data. Nobody wants 10 readings a second, every second, when things are fine - it simply overloads databases. Using the open controls software it is straightforward to attach conditions when and where to send what data. In this example we send data every minute, if it changes by more than 0.03 bar, or if pressure spikes over 3 bar you get the 5 second rapid data in an email.

It works. We have used this on sites to highlight hammer events that have been causing damage to valves. Events that were completely invisible until they were properly looked at.

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