Kabala, Uganda
Air valves reduce air pockets, resulting in 11% increase in flow rate, and reduced energy costs
Background
Background
The Kabala District of Uganda takes its water from Lake Bunyonyi, at an average production capacity of 1900m3 per day.
Challenges
Low water levels, high energy costs
The National Water and Sewerage Corporation faced a number of challenges. The first was that the main source of energy – electricity - cost thousands of dollars every month - a significant expense. This was largely due to low water levels at the
Makanga reservoir - at an average of 0.5m a day, it was well below the 1.0m required to supply most areas by gravity alone. Even at 1.2m, pumps were required. In addition, given the frequent occurrence of local power failures, air pockets would occur along the transmission mains, causing treated water to flow back to the Kiyoora treatment reservoir.
An Area Energy Reduction Committee was established and tasked with the installation of air valves on the/transmission mains. The Committee’s technical team was instructed to resurvey the pipeline from the intake, Lake Bunyonyi, to the main
reservoir, Makanga, trace all buried valves, check their status, and take appropriate steps to replace the old air valves with new A.R.I. air valves by Aquestia.
Solution
Advanced air valve sizing and location
In the course of the resurveying, three washouts and four air valves that had been buried were discovered and found to be faulty, along with four faulty visible valves. Initially, it was decided to replace a total of 21 air valves. However, once the raw data
had been analyzed using ARIavCAD software, it was found necessary to replace just the 11 faulty valves with new A.R.I. D-040 and D-070.The ARISENSE includes internal sensors to track air valve performance and issue alerts of any internal events, and external sensors for monitoring the network, such as a pressure sensor that indicates pressure along the pipeline. This provides feedback on various key operational parameters, including overflow, leakage, blockage, pressure, tampering, and tilt/shock. If any of the sensors, internal or external, is activated, email and text messages are sent to all subscribed users.
In the course of the resurveying, three washouts and four air valves that had been buried were discovered and found to be faulty, along with four faulty visible valves. Initially, it was decided to replace a total of 21 air valves. However, once the raw data
had been analyzed using ARIavCAD software, it was found necessary to replace just the 11 faulty valves with new A.R.I. D-040 and D-070.
The unique A.R.I. D-070 dynamic combination air valve operates without a float, rather using the rolling diaphragm principle. This unique structure allows the dynamic air valve to discharge air from the water system in a controlled and gradual manner,
preventing slam and local up-surges. When vacuum (down-surge) occurs, the valve reacts quickly to admit large volumes of air into the water system, impeding downsurges and, consequently, all pressure surges in the line. The air & vacuum component
of the dynamic air valve prevents the infiltration of debris and insects into the water system by staying closed when the line is not operating.
Result
Improved pipeline efficiency, reduced energy losses, increased flow rate
The new A.R.I. air valves proved to be an efficient solution for discharging air from the transmission mains, improving pipeline efficiency by reducing energy losses and increasing flow rate by 11%. What’s more, water levels in the Makanga main reservoir
are now stable, maintaining an average 1.7m, compared to an average of 0.7m before the valves were fitted (see table below).
