Why should valves be operated this way?

Andrew Talkes

Director and Founder @ SmartValve | Business Management, New Business Development

3 articles

Introduction

Transient pressure surges, or water hammer, are a significant challenge in water distribution networks. These surges can lead to substantial damage, including burst pipes, damaged fittings, and system failures. For water network managers responsible for delivering water to consumers and businesses, preventing these surges is crucial for ensuring the reliability and longevity of their infrastructure. One effective strategy is the gradual operation of valves. This short read delves into the concept, benefits, and implementation of gradual valve operations, providing actionable advice and real-world examples to help water managers mitigate transient pressure surges.

Understanding Gradual Valve Operation

Gradual valve operation involves controlling the speed at which valves open and close to manage the flow of water through the network smoothly. This practice prevents abrupt changes in water velocity, which can cause pressure surges. By ensuring that valve adjustments are made slowly and steadily, the risk of inducing water hammer is significantly reduced.

The Benefits of Gradual Valve Operation

• Prevention of Water Hammer: By avoiding sudden changes in flow, gradual valve operation minimizes the pressure spikes that lead to water hammer.
• Extended Infrastructure Lifespan: Reducing the frequency and intensity of pressure surges lessens the wear and tear on pipes and fittings, leading to a longer system lifespan.
• Lower Maintenance Costs: Fewer incidents of water hammer mean fewer emergency repairs and lower overall maintenance expenses

Key Aspects of Gradual Valve Operation

Aspect 1: Manual or Automated Control of Valve Speed

Role: Ensuring that valve adjustments are smooth and controlled, whether done manually by operators or automatically by control systems.

Process: Valves should be equipped with mechanisms that allow for precise control of opening and closing speeds. Operators should be trained to handle these controls, or automated systems should be installed to manage valve operations.

Benefit: Minimizes the risk of creating pressure spikes by controlling the rate of flow changes.

Example: Consider a scenario where a manual valve needs to be closed to isolate a section of the network for maintenance. Instead of closing the valve quickly, which can cause a sudden pressure increase, the operator takes several minutes to gradually turn the valve, reducing the risk of water hammer. In a small town’s water network, an operator named Sarah implemented this technique during routine maintenance. She noticed that by closing the valve slowly, the usual banging noises and subsequent complaints from residents regarding water quality were significantly reduced.

Implementation: Automated control systems can be designed to open and close valves at a predetermined rate, ensuring consistency and reducing the likelihood of human error. In a large metropolitan water system, for instance, the implementation of automated valve control led to a dramatic decrease in pipe bursts, saving the city thousands in repair costs annually.

Whilst valve operations are a major source of Transient events there are other aspects to consider which can also have a positive impact on the network.

Aspect 2: Integration of Variable Speed Pumps

Role: Controlling the rate at which pumps increase or decrease water flow, directly affecting the pressure within the system.

Process: Pumps equipped with variable frequency drives (VFDs) allow for gradual speed adjustments. These drives can be programmed to ramp up or ramp down the pump speed over a specified period.

Benefit: Provides a smooth ramp-up and ramp-down of water flow, preventing sudden pressure changes that lead to water hammer.

Example: In a distribution network supplying water to a commercial district, a pump equipped with a VFD slowly increases its speed over five minutes at the start of the day, ensuring a steady build-up of pressure rather than a sudden spike, thus preventing potential damage to the system. This method was particularly effective in an industrial park where fluctuating water demands had previously caused frequent pressure issues. The gradual pump speed adjustments ensured that businesses experienced consistent water pressure, enhancing their operations.

Implementation: Installing VFDs on all critical pumps within the network and configuring them to operate gradually can significantly reduce the occurrence of pressure surges. A case study from a water utility in a coastal city showed that after installing VFDs on their main pumps, incidents of water hammer were reduced by 60%, and customer satisfaction improved due to fewer water disruptions.

Aspect 3: Use of Soft Starters for Pumps

Role: Limiting the initial surge of pressure when pumps start, by gradually increasing the electrical current to the pump motor.

Process: Soft starters manage the electrical input to the pump, allowing it to start slowly and increase speed gradually. This process reduces mechanical and hydraulic shock to the system.

Benefit: Reduces mechanical and hydraulic shock to the system, further mitigating the risk of transient pressure surges.

Example: A water treatment plant uses soft starters on its high-capacity pumps. During peak usage times, the pumps start slowly over a period of several minutes, preventing the sudden jolt of pressure that could otherwise cause pipes to burst. In one plant, the use of soft starters not only reduced the occurrence of water hammer but also extended the life of their pumps by 20%, significantly reducing replacement costs.

Implementation: Integrating soft starters into the pump control systems across the network ensures that all pumps start gradually, protecting the system from sudden pressure changes. An anecdote from a water manager in a mountainous region highlighted how soft starters were crucial in managing the high elevation changes in their network, which were particularly prone to pressure surges.

Practical Advice and Action Steps

Practical Pieces of Advice

1. Integrate Automation: Use an automated control systems for valve operations to ensure consistent and gradual changes. Automation helps in maintaining a steady pace and reduces the chance of human error.
2. Regular Training: Continuously train staff on best practices for gradual operation techniques to maintain high standards and reduce human error. Well-trained staff can make informed decisions during manual operations.
3. Maintenance Schedule: Establish a routine maintenance schedule to ensure all equipment involved in gradual operation is functioning correctly. Regular maintenance prevents unexpected failures and ensures smooth operations.

Practical Action Steps

Install Variable Speed Drives: Equip pumps with VFDs to allow for gradual speed adjustments, ensuring smooth pressure transitions.

Action: Conduct an audit of all pumps in the network to identify candidates for VFD installation.

Benefit: Smooth pressure transitions reduce wear on infrastructure and improve system reliability.

Invest in a manual valve Control System: Implement innovative control systems that automate the gradual opening and closing of valves, reducing reliance on manual operations.

Action: Budget for and roll-out an automated valve control system across the network.

Benefit: Consistent and precise valve operations reduce the likelihood of pressure surges.

Conduct Regular Inspections: Periodically inspect and test valves and pumps to ensure they are capable of gradual operation and soft starting, addressing any issues promptly.

Action: Develop a checklist and schedule for regular inspections of all critical components.

Benefit: Early detection of potential issues prevents unexpected failures and maintains system integrity.

Likely Outcomes

Implementing these strategies is likely to result in several positive outcomes:

1. Reduced Risk of Water Hammer: With fewer pressure surges, the network will experience less water hammer, reducing the likelihood of damage. A utility company reported a 70% decrease in pressure-related incidents after adopting these practices.
2. Extended Infrastructure Lifespan: Pipes, valves, and fittings will suffer less stress, leading to fewer failures and a longer operational life. An example from a small city showed that their average pipe lifespan increased by 10 years after implementing gradual valve operations.
3. Lower Maintenance Costs: Reduced incidence of emergency repairs and lower overall maintenance costs due to decreased wear and tear on the system. For instance, a rural water district saw their annual maintenance budget decrease by 30% after implementing automated valve systems and VFDs.

Key Takeaway

Gradual operation of valves is a critical strategy for water network managers to mitigate transient pressure surges. By implementing automated control systems, variable speed pumps, and soft starters, and ensuring regular training and maintenance, managers can significantly reduce the risk of water hammer. This not only protects the infrastructure but also enhances the reliability and efficiency of the water distribution network, ultimately benefiting consumers and businesses alike. Investing in these technologies and practices leads to more sustainable water management and improved service quality.

Given the complexity of modern day water networks the practicalities of installing an automated control system on every valve and hydrant would be cost prohibitive. That is why we invented SmartValve, a patented control system for all manually operated valves. SmartValve supports the work of network technicians guiding them on how to operate valves correctly to mitigate against transient pressure surges (water hammer). SmartValve is currently installed with 4 large water companies and is on course to revolutionise the way manual valve operations are carried out across the globe.

Andrew Talkes: Founder of SmartValve, [email protected]