Page 208 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

Pumping of Liquids 179

Table 3-6
Type Selection Based on Liquid Handled

Liquid Basic Pump Type Type Impellers
Water and other clear non-corrosive Single or double suction Closed except for very small capacities
liquids at cold or moderate tempera-
tures.
Water above 250° F. Single or double suction. This is usually boiler Closed except for very small capacities
feed service at high pressures requiring multi-
stage pumps.
Hydrocarbons, hot Single suction, often of the special type called Closed with large inlets.
refinery pumps, designed particularly for high
temperature service.
Corrosives: Single or double suction
Mildly acid or alkaline
Strongly acid or alkaline Single or double suction with single suction Closed except for very small capacities or
probably less expensive if available for the where liquid tends to form scale on surfaces
rating. of moving parts.
Hot corrosives Single suction, with many refinery pump types
also used here because of high temperatures
and corresponding suction pressures.
Water with solids in suspension: Single suction with end clearance wearing fits. Open, which allows better application of the
Fine abrasives If all particles pass through Ya" mesh screen, rubber, except in larger sizes. Also made in
rubber lined pumps are available which will closed type.
give many times the life of metal pumps, pro-
viding no chemical action or excessive tem-
perature will deteriorate the rubber. Special
rubber compounds can be applied to improve
resistance to certain chemicals.
Coarse abrasives Single suction. Not available for full range of Closed.
ratings, that is, small capacities not too easily
obtained. Often have very large impellers
operated at slow speeds for use when solids
larger than l" diameter are the standard diet.
This would be of the type called dredge
pumps handling sizeable rocks.
Pulpy solids such as paper stock Single suction. Double suction only used on Closed. Open type used to be standard but
very slight solids concentrations and then with change to end clearance wearing fits made
special end clearance wearing fits. closed impellers better suited.