The Feed Water Heater Isolation System from Dewrance, part of Tyco Engineered Products, aims to be a cost-effective alternative to gate valves without the need for major pipework modifications. Dewrance’s fail-safe system prevents water entry through the bled steam pipes into the turbines, which can be caused by blocked drains, defective control valves and burst or perforated tubes, by using the pressure in the pipeline to achieve an absolute shut-off. In the event of high water level in the shell, water is by-passed around the heater using fast-closing tee and changeover valves around the heater(s). In the event of failure of the controlling electric or pneumatic supplies, the main changeover and outlet valves will close, isolating the feed side of the heater or heater bank, thereby providing a fail-safe operation. The Dewrance Feed Water Heater Isolation System uses feed water pressure as its motive power; the system can be fitted with a safety valve which will automatically reduce any increase in pressure from any source in the isolated feedwater area between the two main valves. This safety valve, combined with the quick-acting valves, can be used to prevent unnecessary loss of feed-water to the drain.
