To understand the Isolation Valve Placement in Water Distribution Systems we need to understand what an isolation valve is. An isolation valve is a mechanical device meant to regulate or completely stop water flow within known sections of the distribution network. Therefore, they are in different strategic parts of the piping infrastructure to help in maintenance, repairs, and emergency responses. These are purposely designed and put in place for manual or remote operation and are critical in controlling the flow or isolating sections from other for maintenance or repair or in preventing water loss when an emergency leak or contamination has occurred.

Isolation valves are critical for reliability, efficiency, and safety in a water supply network. This paper thoroughly investigates the importance of isolation valves, goals for strategic isolation valve siting, and the possible arrangements for a water distribution system.

Isolation valves facilitate the gatekeeper to water distribution networks, making isolation of sections of the system possible for maintenance, repairs, or in the case of an emergency such as a leak or contamination event. Without these valves, an entire system may be compromised, which leads to wide service disruption, loss of water, and potential hazards.

The distribution networks of the water supply systems can be arranged in different layouts: gridiron, radial, looped, and branching. Based on these, each has its peculiar issues and the possibility of valve application, thus requiring strategies using the most preferable methodologies to optimize the function and reliability of the system.

Objectives of strategic Isolation Valve Placement

Isolation valves should be located strategically with several important objectives:

• Access for maintenance and emergencies: Valves shall be located to be accessible to maintenance personnel and emergency crews where adequate time can be saved during an emergency.
• Minimization of service disruptions: As such, having valves located strategically can localize the impact of maintenance activities or incidences with minimum service disruptions to water customers.
• Systems redundancy and reliability: Strategic valve location creates reliable systems because it provides a way of offering system redundancy, allowing isolation of failed or damaged sections without interrupting the whole network.
• Hydraulic considerations: One must have the correct view of valve placement for optimal hydraulic performance, assuring pressure management and flow control across the system.
• Cost-effectiveness: A good balance between the costs of valve specifications, installation, maintenance, and operation and the potential savings by minimizing service disruptions and increasing system performance.

Kinds of Isolation Valves:

Gate valves:

The gate valves are characterized by the fact that there is an internal metallic gate, which can move down and up to either let the water in or cut it off. When the gate is lifted, water passes with little noise since there is no abrupt change in pressure. Usually, a hand wheel is put on the top of the valve to control the gate. The turning of the hand wheel makes the inside gate move to the desired place. This sort of valve helps to slow the flow of water gradually. It prevents a potential banging sound in the pipes. This is commonly referred to as a “water hammer” caused by the sudden alterations in the direction of the flow or sudden stops.

Plug Valves:

A plug valve is a cylindrically shaped valve used for isolation or redirection. It takes the form of a cone-shaped plug with a hole in its centre, which turns by opening or closing the valve. The opening and closing of the plug, when the lever is turned a quarter, just turn to let the water flow while closing the hole, align with the walls of the valve blocking the flow. There are different plug valves based on the port shapes—round, rectangular, and diamond each having a different purpose for serving special flow requirements.

Butterfly valves:

The butterfly valve has a centrally placed disc that lies in the middle of the water flow and rotates a quarter turn for opening and closing, very similar to the functioning of a ball valve. By opening the valve, water is allowed to pass, and by closing it, it will enable no water to pass. Butterfly valves are part of the family of rotary motion because they control flow through the rotation of the disc to either open or close. Some designs can be partially openable, but throttling over a substantial part of the range is not advised because of disc wear and inability to seal. Despite the shortcoming in size, these butterfly valves are made to be light-weight, small, and operated with relative ease manually; they are therefore sufficient for the regulation of large capacities of both water and gas.

Ball valves:

A Ball valve is a standard type of shut-off valve in distribution water systems. These valves give water direction through the rotating of a ball containing a hole within it. The flow direction is provided through the alignment of the hole with the pipe, and stopping is provided by the hole being perpendicular to the pipe. They are used for their reliability, speed, and durability, so they are well-suited for frequent use in both residential and industrial setups. They create an extra tight seal so that no leaks are likely and, in addition, can be very useful in a disaster as well. A multi-port ball valve can direct through water more than one pipe.

COMPARISION:

Criteria for Designing Valve Installation:

• Accessible: Valves shall be in readily accessible areas for maintenance and emergency response.
• Redundancy: The valves are installed strategically to give the system the ability to be redundant, whereby a single section can be isolated without total shutdown.
• Hydraulic performance: Valve locations shall be optimum to maintain hydraulic balance and pressure management in the network.
• Cost-effectiveness: The costs of the valves, in terms of installation and maintenance, need to be weighed against the benefits of improved system reliability and performance.

Isolation Valve Placement Strategy Parameters

• Critical points of the distribution network, i.e., intersections and the primary branches, need valves placed in them to minimize service interruption.
• This is a way to locate valves near critical consumers or sensitive areas, such as hospitals and industrial zones, to respond in time to meet the needs of water supply and possible risks.
• Valve installation at pre-determined spacing based on pipe length and diameter to provide adequate control and isolation functions.
• Locational convenience of important infrastructural components such as pumps and storage tanks for service and operational ease.

Case Studies and Best Practices for Isolation Valve Placement:

Case Study 1: City of Philadelphia, Pennsylvania, USA

• To counter the issues in the system, the Philadelphia Water Department (PWD) started its project to restore the decaying water distribution system by introducing a comprehensive valve management program.
• They assessed the condition of each one of the valves and determined which of them was inoperable or in worse condition.
• It was a project that included replacing the inoperative valves and repairing the ones in poor condition, as well as setting up scheduled regular maintenance.
• PWD trained the staff about the operation and maintenance procedures for the valve, and it bought additional new equipment to assist in the operation of the valve.

Case Study 2: City of Toronto, Ontario, Canada

• Toronto Water launched a pilot project on installing intelligent valves in its distribution system to facilitate operational efficiency and leak detection.
• Pilot Areas: Smart valves were fixed at some critical points on the network, such as specially configured regions battling the challenge of leakages and pressure.
• Data Integration: Smart valves were integrated into the SCADA system of the city for monitoring and control in real-time.
• Leak Detection: Advanced analytics and data from intelligent valves to find and pinpoint leaks accurately.

Hydraulic Modelling and Simulation

Optimization of valve placement and system performance is a task that would be incomplete without hydraulic modelling and simulation tools.

• Hydraulic models allow engineers to develop many scenarios and predict the consequence of various strategies for valve placement on system operation.
• Advanced simulation software provides vital insights into flow dynamics, pressure distribution, and water quality to facilitate an informed decision in the design and management of a system.
• The simulation results are interpreted; skills and experience are needed to translate theoretical knowledge into practical recommendations for valve placement and network optimization.

Operation and maintenance of water supply:

Proper operation and maintenance of water supply systems include:

1. Taking water samples to test for bacteria.
2. Testing for chlorine levels in water.
3. Leak detection and sealing.
4. Test water pressure frequently in several locations.
5. Flushing the distribution mains occasionally, not less than a year.
6. Bi-annual check of fire hydrants (fall and spring).
7. Locating and exercising in-line valves annually.
8. Clean the storage tank each year.
9. Inspect the storage tank, screens, valves, and hatches.
10. On an annual basis, overhaul and check pressure-reducing and altitude valve main parts.

Economic Analysis for Isolation Valve Placement:

The cost-benefit analysis for valve placements inside the water distribution system is made by comparing the initial cost of valve acquisition, installation, and connection to control systems against those reduced in water loss, maintenance, and better system efficiency over the long run.

Procurement and installation of intelligent valves, SCADA, IoT technologies, and integration may involve a high upfront investment. However, these costs are often offset by a reduction in non-revenue water via leakage reduction, reduced energy consumption due to more efficient pressure management, and savings on emergency repairs. In addition, improved system reliability and service quality bring satisfaction to the customers and help satisfy the regulators, leading to further indirect financial benefits. Overall, such high initial costs can be justified in the long term through savings and operational improvements, making these investments worthwhile, often with a return on investments realized with time.

Regulatory and Standard compliance:

Basic standards and guidelines are necessary for any water distribution system to ensure that water is supplied safely and reliably.

International Standards:

• ISO 24512:2007 – Activities relative to drinking water and wastewater services. Guidelines for the management of drinking water utilities and for the assessment of drinking water services.
• ISO 24513:2019 – Service activities relating to drinking water supply systems and wastewater systems.
• ISO 24516-1:2016 – Guidelines for the management of assets of water supply and wastewater systems — Part 1: Drinking water distribution networks.

American Standards:

• American Water Works Association Standards (AWWA):
• AWWA C651-14- Disinfecting Water Mains.
• AWWA C600-17- Installation of Ductile-Iron Water Mains.
• AWWA M31 – Distribution System Requirements for Fire Protection.
• AWWA M28 – Rehabilitation of Water Mains.
• ANSI/AWWA D100 – Welded Steel Water Storage Tanks.

European Standards:

• EN 805:2000 Water supply – Requirements for systems and components outside buildings.
• EN 12201- Plastic pipes for the conveyance of water supply and drainage and sewage under pressure.

Australian Standards:

• AS/NZS 3500.1:2021 – Plumbing and drainage
• AS 2419.1:2005 – Fire Hydrant Installations: System Design, Installation.

Guidelines and practices:

• WHO Guidelines for Drinking Water Quality—Sets out international benchmarks for the quality and health requirements that should be met by drinking water.
• EPA (Environmental Protection Agency) Guidelines: Many guidelines like Drinking Water Distribution Systems Best Practices Guide.
• CIRIA (Construction Industry Research and Information Association) Guidelines: These guidelines provide the UK with advice on water distribution system design and operation.

Future Trends and Innovations:

Intelligent valves and remote-control systems are currently revolutionizing the water sector by increasing efficiencies, reliability, and real-time management of water distribution systems.

The different smart valves used include:

• Pressure Reducing Valves
• Flow Control Valves
• Remote Shut-off Valves.
• Smart Actuated Valves
• Non-Return Valves

Supervisory Control and Data Acquisition (SCADA):

SCADA means Supervisory Control and Data Acquisition. It is a central monitoring and control system that caters to all the activities of the water distribution system. The system collects the real-time data from various devices, including sensors and others, that make it possible to make informed decisions and automate activities.

Conclusion:

Water distribution systems require isolation valves for control, efficiency, and safety. The valves should be located at strategic points in the network to ensure that maintenance, repairs, and emergency interventions are carried out with minimum disturbances in service. Considering types of valves, design criteria, and strategies for placing them in a given network facilitates optimized hydraulic performance and system reliability. It is operational considerations, such as maintenance and testing, that ensure these two latter points are carried out regularly. The economic analysis presumes that even if considerable investments are needed during installation, the advantages in the long run about reduced water losses and both O&M and operational efficiency are much more than the costs hence the investment is recoverable. Compliance and safety are assured through international, national, and regional standards and guidelines. Future trends and innovations, such as intelligent valves and personnel–based SCADA systems, have the potential to offer even greater efficiency and responsiveness for water distribution systems. Implementing modern technologies can bring real-time management into the water utilities at large; the system performance and customer satisfaction will be improved, making a more resilient and sustainable infrastructure for water supply.

Reference:

https://dec.alaska.gov/media/11476/chapter-5-intro-to-water-distribution.pdf

Fiorini Morosini, A., Caruso, O., Costanzo, F., & Savic, D. (2016). Emergency Management of Water Distribution Systems: the Nodal Demand Control.

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