Gas turbine Building ventilation system


Thread Starter


In Siemens Gas Turbine (SGT5 4000f) Design, the loss of a HVAC package will initiate trip to Gas Turbine. We have 6 (5 Running + 1 Stand-by) numbers of HVAC packages each has 3 flow switches (2 out of 3 Logic) to monitor the proper ventilation flow to the Building. This will ensure small positive pressure inside the building. The present logic is, when Ignition gas or Fuel gas is present inside the building (Based on valve position feedback) this will generate ventilation system required signal. Loss of one HVAC package (only 4 running) with the ventilation required signal will initiate trip to Gas Turbine within 10secs and also will vent the gas respective to Zero pressure (Same as fire protection). I couldn’t imagine the significance of ventilation system here as the Gas Turbine will not dissipate more heat that may leads to danger. Do we need to have this much stringent controls for ventilation system?

Kindly explain the importance.

Thank you.
Do you think this stringent control is mandatory?

Share your experience in this regards.

Thank you.

> The fear of a gas leak and the potential for an explosion and/or fire
> is probably the most important reason.

You need to ask:

1) Your local and national regulatory agencies (industrial safety; code bodies; etc.)

2) The company that insures the equipment at your site

3) Your site safety manager/supervisor (though it's pretty much guaranteed they will not question whatever the equipment supplier provided)

4) The lawyers who would represent your site in the event of an issue related to a gas leak

5) Your equipment supplier's lawyers and insurance company

For me, personally, it is excessive. For lawyers and safety managers/supervisors, it's a matter of protecting their jobs. For plant managers and owners, they don't want to question what the lawyers, safety managers/supervisors, or insurance companies tell them.

Having worked for a gas turbine OEM, I can tell you the lawyers rule, and fight for supremacy with the safety engineers/managers. The onerous requirements they put on modifications to existing systems with the inclusion of schemes similar to what you describe have lost hundreds of millions of USD in jobs because of the cost increases due to the "required" safety schemes which must be provided per the safety engineers and lawyers.

Is it warranted? Unfortunately, it seems to be. With the proliferation of gas-fired power plants and the lack of training and knowledge of operating and maintenance personnel there have been a proliferation in the incidents of fires and explosions, most kept quiet by owners and insurance companies. I have personally been to power plants that ran on liquid fuel (distillate or heavy fuel oil, even naphtha) for decades, but when converted to gas fuel or if new gas fuel-fired generation is being installed the existing plant personnel just FREAK out because the (suspected) "dangers" of natural gas.

Fuel leaks will always occur; particularly if proper assembly and testing and maintenance procedures are not followed--and if proper safety measures are not in plance and observed. Leaks can be mitigated, but never prevented.

Are the present measures excessive? Probably somewhat excessive. In my personal opinion, they are new and unreliable--and that's the real problem. They are unreliable. As such, they seem more onerous and excessive than they really are.

As for being "mandatory," again, that answer lies in the purview of the lawyers and insurance companies and regulatory agencies and site safety personnel (in that order--though site safety personnel, in efforts to cement their jobs and prove their necessity to plant operation and maintenance often go way too far with their additional requirements, exceeding all others for not very good reason, and generally because of a lack of understanding and knowledge of operating procedures and practices and necessities).

Hope this helps. It's by no means an official statement--I'm not a lawyer or an insurance actuary, nor a safety enforcer ("Danger Ranger").

I'm a FIRM believer that Internet forums are for the benefit of many people, and rarely take discussions off-line.

I've been rightly accused of providing too much information at times, but that's because a LOT of people read these posts over years (those who use the 'Search' feature of, and everyone has a different experience set and base of knowledge and understanding. So, I try to provide information that is pertinent and useful (and editorialize occasionally) when it's appropriate.

So, if you have a question, there are lots of people who may be able to answer your question here--or provide additional details. And the answer(s) to your question(s) can help MANY people if you post them here and engage in an exchange of information. Whereas if we take the discussion off-line, only one person benefits (two actually; I learn from every post I make!).
Yes Mr CSA,

I am a keen follower of your replies. It gives more insight and clarity in the subject. By encouraging the discussion in open forum many people like me get benefited.


I appreciate your thought.

Nonetheless i have some doubts related to GT control logics and i would like to explain you with some corporate documents to understand better that cannot be possible in public forum.

Thank you to your understanding.