The gas filter assembly comprises a casing which has an inlet port means for receiving gas to be filtered and an outlet port means for passing filtered gas to a place of storage or use. A filter means is disposed within the casing between the inlet port means and outlet port means to disentrain solid particles entrained in the gas stream. A portion of the walls comprising the casing are pivotally connected to their fixed or associated wall portions. All of the pivot axes are located close to a common plane so that the pivotal wall portions can be rotated to a folded or collapsed position to reduce its overall size and facilitate transportation of the assembly and then unfolded or extended to its full size position for ''''field'''' or on-site erection of the assembly.