In 2016 I participated in a panel discussion titled “Ageing water and sanitation infrastructure” arranged by Institute of Municipal Engineering of Southern Africa (IMIESA).
I was reminded of this when the subject of our ageing water supply infrastructure was raised during the 2019 State of the Nation Address in February.
My comments were later published in the institute’s magazine. I think they’re as relevant today as they were 3 years ago. I hope you find them useful. Here they are…
How important is pressure management and how has it been implement in South Africa?
With water scarcity facing users all over the world, water utility companies should be proactive to ensure that pipe leaks are reduced and kept to an absolute minimum. One of the best “fast return” innovations, which has been implemented by some municipalities and water boards over the past few years, is pressure management.
This involves reducing pressures in networks during low-demand periods (to reduce losses from leaks), which involves electronic equipment connected to pilot-operated pressure reducing valves (POPRVs) that resets pressures to different levels for different flow rates.
The problem with this strategy in the South African context is that POPRVs are complicated and little understood (or maintained) by operators. The addition of electronic controllers makes these valves even more complicated and less user-friendly.
Ultra Control Valves has entered the market with some very new and simple innovations, which are starting to capture the imagination of users as tremendous water saving devices.
What are the advantages of RRPRVs over POPRVs?
Ratio reducing pressure reducing valves (RRPRVs) reduce pressures in a ratio (2:1, 3:1, 4:1, 5:1) and have no adjustments that are easily tampered with. They also are much easier to apply in the field as they do not have delayed reaction times, low flow instability or vulnerability to dirt. Just a simple piston, which is activated by line pressure, which will always keep the ratio between inlet and outlet pressure at a constant value.
With POPRVs, one has to be very careful that the valve is sized correctly to handle low flows, or install valves in series to overcome cavitation damage, all increasing the complexity of the installation and with increased chances of malfunction.
In a lot of POPRV installations, valves become unstable at low flows (at night), causing pipe breaks and leading to huge water losses – exactly the opposite result to what the valve is intended for.
The installation of RRPRVs is a lot simpler and does not require much engineering or maintenance. It is truly an African solution to keep pressures low without the accompanying complexities.
Tell us about Maric flow control valves and their applications in Africa.
This innovative Australian product has been used to control flow in a lot of applications over the last 40 years since its development.
These valves are completely tamperproof and absolutely ideal for African conditions – where simplicity and robustness are key, and maintenance is seldom done.
In the right applications – such as consumer end points like taps, showers, stand pipes in rural water supplies – this valve will ensure tremendous savings of water consumption.
It will have the same effect in water supply networks. By placing Maric flow controllers in strategic positions, flows are limited to what is the norm for such a network. If the pressure drops to the extent where users complain, it indicates that consumption is too high due to pipe leaks, which then need to be repaired.
These products provide pressure and flow control with absolute simplicity, which plays an important role in ensuring correct operation. The end result is huge savings in water losses.
Original magazine article and accompanying advert below.