As mentioned in an earlier article, one of the three N.F.P.A. cylinder mounting classes is fixed non-centerline mounts. These mounts include side lug (MS2), end lug (MS7), side flush (MS4), and foot bracket (MS1). In applications where a fixed non-centerline mount is required, Sheffer strongly recommends employing a thrust key plate or dowel pinning the cylinder depending upon the specific mount. This is done to minimize shear loads on the mounting bolts as well as providing a means of cylinder alignment.