Hi all.. I'm looking for a recommendation for a particular component- a VERY reliable gas valve.. to be used to control standard mains Natural Gas and/or Propane. What I'm looking for is a reasonable Solenoid valve which is normally closed, requiring application of current to the coil to open the valve (failsafe). I'm prototyping, so if whatever I end up making ends up being produced, it won't likely use the same part in production.. so I'd prefer as cheap as I can safely get away with in a prototyping environment. The biggest key elements are the valve being leakproof and also of course rated for use with flammable gas.
Trust me, I know the risks involved with gas.. it's the very reason I am looking at this. I'll be doing all development just using compressed air or something similar; I'd move on to controlling a propane torch cylinder as a fuel source in a final prototype if it goes that far. I am not in any way proposing actually using mains gas, or using flammable gases of any type during development and testing, especially indoors. I DO NOT recommend that anyone consider a project of this type without understanding that if it does go wrong, people can die.
I'm designing an intelligent gas-line mains cutoff, Arduino running the show. Open source to make the design as widely used as possible, save as many lives as possible. Though the basic idea is simple, if I can get this rolling, I'll appreciate any input along the way.
Specifically, the controller should provide status display, be able to monitor remotely located (Zigbee, most likely?) sensors (CH4, Temp, and CO and possibly Infrared Diffusion Smoke), and provide for failsafes at as many turns possible. It should be resettable by a non-technical home owner, but also act as part of a larger system if desired (integrating to existing alarm/fire control systems). However, a "ultra-basic" form of the device, incorporating only the core functions and wired sensors, should be first, as it would be lowest cost and therefore the largest use where it is needed most- in rural and remote areas, where Fire Department response times can be measured in hours in some places.
Ideally, it should cost as little as possible, and be able to be assembled from commonly available parts by any typical mechanical assembly shop.. Propane explosions in remote areas are extremely common. If something like this can become standardized, the savings in property and lives would be huge. It's tough for a family to get Carbon Monoxide Poisoning when the whole gas feed is automatically cut the first moment a sensor detects it in the air... or for an explosion to occur if a pressure-feedback sensor notices there's no backpressure in the line, indicating a broken line inside. I know this is possible- and I think we can make a better mouse trap if we set our minds to it.
The idea simply being a range of sensors, be they gas, fire, or earthquake (geophone) or whatever is needed in a particular area all reporting to a central Arduino, which acts as simply monitoring the inputs, and if any one of them goes out of range, shut off the mains feed to the residence. Since I propose using a valve which requires power to keep the line open, even a fault in the control system results in the gas feeds being cut off; it's much safer to have to actively hold a valve open than try to close one after something has already gone wrong.. closing the barn door after the cows are gone and all that logic.
I know of no open source project for this, and it's a cause very near to my heart. As a teen, I lost my parents to just such an explosion; within the last several days, there have been several deaths locally due to gas system malfunctions. It shocks me that given the technology we have within our grasp, that these stories still occur almost daily. there are a few commercial valves available- but they are VERY expensive and hard to get. I'd like to see something that becomes "normal" when gas of any type is used.. without cost being the holding factor. I'm talking about something that would have a finished cost of under $200 with a basic set of fault sensors. Mass produced, that would likely make it do-able in the $100 range, to my mind. Cheap money for saving lives. I can imagine that if the simplest form- a single inline valve box with built in backpressure, CH4, and CO sensors were built as a required component for new gas installs, the production volume would make them under $50. In an ideal world, something like this would be subsidized to low income housing (least likely to maintain heating systems, highest rate of equipment failures).
Feedback and suggestions? The sensors are fairly standard fare, the code should be actually pretty basic stuff... but the valve is the key. I'm seeing things that are priced from as little a $10 to over $400.. Obviously the Medical-gases valve is overkill.. but do I dare even prototype with a $10 jobbie? Does anyone have experience with this kind of valve?
