sludge pump[′sləj ‚pəmp]
a machine tool used in the drilling and operation of boreholes to raise liquids, sand, and sludge to the surface. Sludge pumps may be of the simple boring type, the piston type, the clamshell type, and the pneumatic type.
Boring sludge pumps consist of a hollow steel barrel or pipe, which has a shackle in its upper part that is used for connection to a cable or a rod and a valve in its bottom. Such pumps are used in percussion drilling without flushing for cleansing the borehole face of rock crushed by the bit or of sludge, as well as during boring in sand, quicksand, and gravel. In percussion drilling for water, sludge pumps are used for experimental pumping and for priming. Piston and clamshell sludge pumps are used in prospecting for field deposits. Pneumatic sludge pumps are used in ridding boreholes of sand plugs. A special type of sludge pump is the so-called bailing pump, which is used in pumping oil and brine; this type is not used in the USSR.