Fashe-fashe na faruwa a cikin wasu iyakoki, musamman a cikin iyakokin abubuwan fashewa.
Iyakar fashewar CH4 a cikin kewayon iska daga 5% ku 15% maida hankali na methane. Wani fashewa zai faru idan adadin methane na volumetric ya faɗi cikin wannan 5% ku 15% kewayo kuma ya zo cikin hulɗa tare da buɗewar harshen wuta.