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Can you put LPG into a CNG tank?

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  • Can you put LPG into a CNG tank?

    I'm new here. Spent a few hours reading up on this forum and didn't find the answer to it. I realize you can't do it the other way but is it possible to put LPG into a CNG tank? I'm guessing it's possible and probably safe but the fill and the valves aren't correct. I would also assume once it's used for propane it can't go back to CNG. I know it's a long shot but I remember somebody at some point on some forum claimed you could (reliable info I know).

    I live in Portland Oregon and I own several classic cars I'm interested in doing a dual fuel conversation (gas and propane) on. However Portland is a big black hole for CNG fill stations and even though PGE and Eaton promised a $500 compressor it seems that is still not a reality. I also find a lot more lightweight used CNG (still a long ways from Hydro date) for cheaper than I can find a lightweight propane tank.

  • #2
    Nothing is impossible. But, switching from CNG to LPG would be a major effort. Why would you want the extra weight? And you're right all the valveing, transfer lines and regulation would have to be swapped out. I think it would be better to tear out the CNG system in start from scratch. Respectfully submitted AFV man


    • #3
      Agree with afvman. Even the lightest weight carben fiber cng cylinder will be about 3 x the weight if a steel LPG cylinder.

      On the low cost cng compressors, It would be more likely to have a merger of the united states and north Korea. Those press releases on compressor tech and price were pure hype.