Tele, what you are missing is that this is a cutoff for residential use. It is specifically being designed for the purpose, and recent manufacturing changes has drastically reduced the pricing of key components (for example, MQ series sensors).
I'm kind of curious as to why integrating the gas detector (among other sensors, including inline pressure sensors both before and after valve) into the residential valve is such a bad idea in your opinion, considering that such equipment can exist for reasonable cost. And actually- the flammable gas detector you advise would still leave my parents dead and three kids orphaned. Since it was primarily the crawlspace where the leak occured, with little in the basement, a single alarm in the basement (normal placement) would have been of dubious value, even if they had existed at the time. However, an inline pressure sensor would have sensed the drop in line pressure and lack of backpressure in the line.
Let me ask you this: Such devices exist, cost has been the prohibitive factor, as you pointed out. Only major expense operations could or would afford. Now, you recommend that gas detector, somewhat effective- but why wouldn't you integrate that ALARM into a CUTOFF? The very same sensor you recommend is the sensor in my design- except I go further in the full design, correlating across several sensor types to minimize false alarms. In addition, I am proposing a change in valve standard from NO to NC. Positive action via solenoid required for gas to flow. Simple. There's no legitimate reason for gas to be on to residence if the power fails. Using the stove for heat means death by CO poisoning. Since a manual bypass could still be enineered in (though why it would be is beyond me) there's still no drawback. Happily, MQ series sensors detect CO. The design also allows for both wired and RF linked sensors (2.4Ghz or 350 Mhz modules), which allows for multiple location monitoring for cheap. Last but not least is that I plan to provide for integration into existing domestic alarm systems. Addition of bluetooth or web interface is as simple as an SD card and ethernet or bluetooth module. What I did for the video was not for technical folks. I wanted it to be simple and straight to the point. My 84 year old father in law got it the first time he saw the one minute demo video.. which was the intent. Trying to explain all the other stuff wasn't needed, and wouldn't help. He, like most people, didn't know that this type of thing was even possible, much less within reach. By the way, my neighbor, an OSHA inspector, is also intrigued. Seems that maybe, just maybe, I might be the right guy in the right place saying the right thing at the right time, if I can pull it off. That's the goal.
The demo I did for the video was extremely simple, just using a single MQ2 sensor. Calibration isn't necessary for this demo because it operates on a delta rather than absolute (though absolute threshold is there too)... it senses a drastic change from sample to sample, therefore it is an alarm situation. Rapidly rising gas concentration in the environment? Shut it off... everything else is secondary. Further, as the system is "smart" (not simple mechanical) it could also provide data and remote cutoff potentially, to the utility.
The reality is that this can happen now. The technology is affordable and reliable enough for this purpose- your recommended alarm shows that show this to be the case (as does the one I have, and have had for years, I am quite reasonably a little paranoid about such things). What it really needs is a catalyst. I am trying to be that catalyst. I am willing to tell my story, and offer a possible solution (even if it isn't the one eventually implemented) to get this ball rolling. I did an interview for Patch.com which will run on Monday, and I hope to be talking with two local television stations next week. Even if I totally fail, I can try. If pulling together twenty five grand, trivial in terms of R&D money, has even an outside chance that it could make this happen--- I'd be a fool, and possibly be unable to feel too good about myself if I didn't give it all that I can... this is thirty years of an orphaned teen's motivation. I want to make this happen for every right reason there is, and I don't care at all (Though I probably should) about making money from this. It's about saving lives, It's about the idea that I may be able to prevent others from knowing what it is for the air to be on fire, concussion injuries, and the horror left behind. I won't lie, thirty years later and there are times when.. well, let's just say that the nightmares and occasional daymares still won't stop completely. Maybe I can make a little peace with a few demons by doing this, while I am at it.
As I said, the technology is relatively trivial. The cost has become so. What is needed now is capturing the public's imagination, a groundswell. In November, a house blew up right here in my city (Crossroads, too) and the guy died. There's a story every day of this. I barely survived.. my home and parents didn't, and not a single thing has changed in terms of the valves since that day. The same fault that killed them could kill anyone. Any time. Given that, how can I not try to change it?
Considering that I have at least an outside chance of success, particularly if I can engage the proper resources- of creating some meaning from the tragedy, wouldn't it be the largest sin of all to NOT try?