Confined vapor cloud explosion CVCE

Especially, for gaseous mixtures exploding in the open the term unconfined vapor cloud explosion (UVCE) is used, whereas when it explodes in confined spaces the term confined vapor cloud explosion (CVCE) is used. In a very poor or very rich fuel mixture, but still within flammability limits, the flame front travels in the cloud at low velocity and insignificant pressure increase—a phenomenon known as flash fire. 

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