Gaseous Systems Are Reliable
I read with great interest the article “Gas Turbine Fire Protection” in your April issue.
Most turbines, as the article points out, have been protected with gaseous agent systems, which when they operate as intended, will extinguish a fire with little damage and, hence go unreported. Failures are always reported. This gives a skewed picture of their reliability. One of North America`s largest users of gas-type fire suppression systems did a 10-plus-year study of thousands of system operations wherein they were able to document reliability in excess of 95 percent successful suppressions. There is no reason to believe that the reliability of systems installed on turbines should be any less, if systems have been properly designed.
Production of halons has been banned by the world`s developed nations for a number of years and some are even implementing programs to remove systems now installed. While we have a limited supply of recycled halon, it is not practical to use it for any purpose except refilling. The use of halon on gas turbines is a thing of the past.
During the great gas turbine boom, following the Northeast black-out, many turbines were installed that are still in service. These protection systems are over 25 years old and need to be modernized. Lack of doing so greatly increases the chance for failure.
There is a statement: “The standards for suppression agents do not address the length of the (gas) retention time.” While no specific times may be given in the standards there are admonitions to ensure that gas concentrations be held until ignition sources (i.gif. hot metal surfaces) have been removed.
There is also a misunderstanding of the purpose of a reserve supply system. The reserve will probably not put out a fire if the main gas supply discharge has not done so. The purpose of a reserve is to maintain protection, after a system discharge, while the main gas supply is being replaced.
It is stated that turbine manufacturers do not recommend a full discharge test. However, NFPA Standard No. 12 states “A full discharge test shall be performed on all systems.” However, where multiple units are built identically, a full discharge of just one will usually suffice with a functional test done on site for every unit. Such tests verify performance of design and components and should be preceded by preliminary tests to minimize failure of a final test. An 80 percent failure rate of the `turn-over` test is inconceivable. I have tested thousands of systems and failure of such tests are very rare.
Social Responsibility Needed
Power Engineering is a fine magazine. It features many insightful articles which are useful to me.
One thing about the magazine bothers me, though. Sometimes Mr. Zink mocks environmental concern in his editorials. April`s editorial, “FERC Makes Fishy Decision,” is a case in point. It is possible to argue rationally against FERC`s decision. Why drag in hyperbole?
I would think the publishers of a magazine of some national prominence would adopt a more socially responsible viewpoint. These editorials could come to be an embarrassment to the magazine. They are certainly an embarrassment to me as an engineer. I think most engineers and most of your subscribers would share this feeling.
This magazine represents, deliberately or not, the engineering profession. I don`t know if Mr. Zink is an engineer, but he is not a good spokesman for engineers. An increasing number of us make our livings dealing with environmental problems. We don`t want a strident editorial voice making us look like minions of polluting industries. Please give us a more mature and thoughtful representation.
Institute of International Education, New York
Weigh Environmental Costs
I enjoyed reading your opinion, “FERC Makes Fishy Decision,” in April`s publication. You pointed out something that has long plagued the power industry, governmental regulators and environmentalists: striking a balance between the benefits and costs of power production.
It doesn`t take a “modern-day Luddite” to recognize the problems inherent in systems which limit or destroy habitats for entire species. We must insist on the rights of nature and humanity to co-exist in a healthy environment. Given the choice between strip-mining coal operations and hydroelectric dams, most of us would agree that hydropower is a cleaner renewable resource.
Given the choice between hydropower and solar power, however, we would certainly choose the latter. Very little can be done to further destroy habitats in areas where we have already constructed homes and businesses whose rooftops can be used to locate photovoltaic panels.
With regards to the reclassification of the snail darter from endangered to threatened, that is neither surprising nor unprecedented. The American Bald Eagle, once endangered, has been reclassified as threatened. This does not mean the U.S. Fish and Wildlife Service made a mistake in the original classification. It does mean that, through the efforts of environmentalists and industry, we have helped to restore the habitats of the snail darter and the bald eagle.
Certainly environmental, economic and engineering solutions must be balanced. It appears the engineering and economic solutions can no longer outweigh the environmental costs. We have to change the way we do business.
University of Virginia, Crozet, Va.
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