Case Study: Controlling Water Flow in Salalah, Oman
By Singer Valve
Singer Valve works with Larson Toubro to install 12 Altitude Valves to control water flow from pipelines to large reservoirs.
Salalah is a coastal city in Oman, about 1,500 km South of Dubai. Although they have an average population of 200,000, tourists flock to this beautiful city for the temperate summer climate. The city gets its water from a desalination plant that has the capacity to process 30 million gallons a day. This water then goes through a 105 km transmission line with DN 1200, DN 700 and DN 600 mm DI pipes into respective reservoirs that supply water to the residents as needed.
As the city and neighborhoods are expanding additional transmission pipelines and booster station was needed to be able to efficiently fill reservoirs for a combined holding of 180,000 cum. Initially, they were looking at installing float control valves on the reservoirs to control the water level, but the application was more suited for Altitude Valves. Float valves in these large sizes would have been too slow and had a sluggish response.
Rajive Khosla, the Singer Agent with Al Mutawaa Trading, recommended 12 Singer Altitude Valves. These valves were to be installed on the inlet line to the reservoirs in chambers that would make for a better installation and easily serviceable at ground level. These altitude valves, ranging in size from DN 300 to DN 800 mm would have an immediate response to flow levels with positive shut-off and no overflows.
Singer’s 206-A Altitude Control Valves are ideal for maintaining a preset maximum water level, which is what this reservoir required. The valve functions as a two-position control valve, either fully open or fully closed. It allows normal forward flow to fill the reservoir to the maximum level and then closes drip-tight at the set-point. It opens to refill the tank once the level drops to a fixed distance below the high water level. This draw down level is adjustable should the city choose to change the refill levels. Another advantage to the 206-A Altitude Valve is the large sensing diaphragm that ensures high accuracy for level control while the inner rolling diaphragm provides superior flow stability.
More articles from Express Water
The installation was carried out by Larsen Toubro and Singer Valve provided technicians on site for the commissioning which took place over two days. At the time of commissioning the water pressure was not readily available and the tanks were so large that Singer Valve’s Factory Representative, Ramzi Soujah, had to get creative to set the levels of the valve. They connected a rubber hose to the Altitude Pilot’s sensing line, and used it as if it was the tank level. With the hose in hand, they got a person to stand on the scaffolding, and make a mark on the reservoir outside wall, where they needed the valve to close. Then the rubber hose was filled with water and as it was raised and lowered, the Altitude pilot was able to sense the static level “h” and they were able to set it in that manner. “We set 4 valves this way and the beauty of these Singer Valves, is that they are repetitive, meaning once you set it, it maintains the setting and opens and closes at the same point each time,” said Mr. Soujah.
Another unanticipated change on site was the conversion of the Valve from 206-A-Type IV to 206-A-Type II which involved disabling the Pilot.
This way there is no differential and filling of the reservoir is immediate as the water drop is sensed. Taraknath Haldar Project Planning Manager with Larsen & Toubro, the engineering contractors for the project said, “It was invaluable having the Singer team on site, to make instant changes”.
All of the valves have a 316 stainless steel seat, which is superior on the wetted surface and 18/8 stainless steel fasteners that won’t rust.
Resilient Heat Fusion Epoxy Coatings are used internally as well as externally and are NSF approved to be safe for use with potable water.
© Express Water. Send us your articles & case studies at [email protected]