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