The upper portion of housing 4 contains the aforementioned impeller 6 immersed in a viscous fluid 18, {HEAD ~ the fluid} completely fills {TAIL ~ the upper portion} of housing 4 
completely fills
The upper portion of housing 4 contains the aforementioned impeller 6 immersed in a viscous fluid 18 , { HEAD ~ the fluid } completely fills { TAIL ~ the upper portion } of housing 4
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH