By Scipp Zeng
San Diego, the eighth largest city in the United States, is situated on the southern tip of California near the Mexican border. With the Pacific Ocean as its western border, this coastal city of 1.3 million is home to the largest naval fleet in the world and is one of the world's prominent wireless communication and biotech industrial hubs. However, nearly nine out of 10 gallons of the county's drinking water has to be imported from the far north of the state.
The San Diego County Water Authority (SDCWA) provides safe and reliable water to the county of San Diego and its 3 million inhabitants through large-diameter water transmission pipelines, reservoirs and flow control facilities. At its Escondido Crossover Pipeline Terminal Station, the Water Authority operated two plug valves to regulate flows in hundreds of miles of its transmission pipeline systems.
However, these plug valves used at the terminal station had difficulty withstanding the excessive cavitation and vibration caused by extreme pressure differences. Local residents complained about unbearable cavitation noise and vibration that not only badly damaged the valves but nearby homes as well. As a result of the damage, the valves had to be replaced every three to five years.
The SDCWA needed to find a solution to this problem, so it started looking for valves that were more resistant to cavitation and vibration. As such, the Water Authority chose the RIKO® Plunger Valve based on its ability to control the flow of water under high pressure while minimizing cavitation and vibration. A custom-control outlet was added to the valve to meet the specific flow and pressure requirements for cavitation-free operating conditions.
The valves had to be delivered and installed in a seven-day window in order to minimize the impact of the system shutdown. This meant that construction, coatings, custom actuation, production, documentation, and delivery had to be carried out on time in order to meet the needs of the SDCWA.
Accordingly, just two days before the plunger valves were scheduled to be installed, they reached their final destination -- the Escondido Terminal Station. Staff from actuator manufacturer Auma was ready and waiting to connect the actuators and put them into operation. The assembly and installation of the two 36-inch plunger valves ran like clockwork -- everything went according to plan. Then came the moment of truth: putting the valves into operation.
It took just minutes for everyone to realize that the new plunger valves didn't vibrate. The maximum noise level of 95 dba met the specification requirement and was much lower than the previous valves. The noise level was confirmed by a sound level monitor installed inside the valve vault. The lower noise level would not only enable the nearby residents to sleep better but also put a stop to the extensive wear and tear on the valves and downstream pipes at the terminal station.
SDCWA's staff was thrilled. "We can now stop using the other control valves, which proved to be unsuitable for this terminal station," said Steve Carpenter, system maintenance supervisor. "We are really pleased...and intend to equip more of our flow control stations with custom RIKO Plunger Valves."
To date, the SDCWA has put more than 30 pieces of plunger valve into operation in its system.
About the Author: Scipp Zeng, BSME, senior product manager of Valve and Gate Group, was the lead on this project. He has more than 15 years' experience in the valve industry. He also has supplied valves and serviced a variety of facilities relating to chemical processing, water supply, water transportation, water treatment, wastewater, and hydropower. He is a member of AWWA and ASME.
