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Someone made the comment that it's dangerous to have a ball valve partially open when used with natural gas in a fire pit. I wasn't able to get any more details as to why, but I've operated fireplaces with a key ball valve partially open prior and didn't seem to have any issues. Is this a valid concern and if so, why?

g491
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  • Did the comment mention if using the ball valve on a water line partway, the water might damage the seals? Just asking if the same comment. – crip659 Jun 27 '22 at 21:56
  • @crip659 They said gas specifically, it's the last paragraph of https://diy.stackexchange.com/a/251870/135898 which says "For gas, it is way different. You want it full open or full closed. It would be dangerous to have a gas valve partially open.' – g491 Jun 28 '22 at 02:34
  • Gas rated ball valves dangerous at partially opened? I don’t think so, they are not normal flow control devices but I can set a flow at a glance, a gate valve in most cases residential you have no idea where the valve is adjusted to. With the handle in-line there is full flow with the handle at 90 there is no flow in between the flow is adjusted dangerous no is the adjustment exact based on the handle position at full open and full closed it is in between it is not exactly linear but most can figure it out and there are no leaks so how is this dangerous sounds like a guess to me. – Ed Beal Jun 28 '22 at 07:35
  • The answerer referenced above clarified his response about a partially open gas valve being dangerous: "If the pressure regulator isn't getting a full flow of gas, it may not operate correctly. The flame could go out. There are safety mechanisms to shut off the gas when that happens...but it just seems dangerous to me. I'd rather have it working reliably." – Fredric Shope Jun 28 '22 at 13:41
  • Thanks yeah looks like they just responded to it – g491 Jun 28 '22 at 15:02
  • with a ball valve partially open the working surface of the gasket is exposed to the flow and may collect or be abraded by debris carried by the flow. also physical pressure may cause the gasket to flow into the ball's aperture preventing the ball from seating properly – Jasen Jul 01 '22 at 06:24
  • Okay, so with low pressure natural gas (i.e. 0.25PSI / 7" WC) and it just being open for short periods of time (i.e. fire pit use), that concern's probably not the same as with a ball valve for water or something high pressure that is more likely to carry debris @Jasen? – g491 Jul 01 '22 at 14:49

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