## Nomenclature

NOTE: The units for each quantity defined are as stated in this nomenclature, unless otherwise specifically stated in the text, equations, figures, or tables.

a = constant of the diffuser or volute configuration in Pfleiderer's slip relation.

Ap = area of flow passage normal to the flow direction, ft2 (m2).

b = width of an impeller or other bladed passage in the meridional plane, ft (m).

NOTE: When dealing with radial thrust, b2 includes also the thickness of the shrouds.

Cp = specific heat of liquid being pumped, Btu/(lbm-degF); [kcal/(kg-degC)].

D = diameter; unless otherwise subscripted = impeller exit diameter, ft (m).

Dh = hydraulic diameter of flow passage (= 4AJp ), ft (m).

g = acceleration due to gravity, = 32.174 ft/sec2 (9.80665 m/s2) at earth sea level.

go = constant in Newton's Second Law, = 32.174 (lbm-ft)/(lbf-sec2). (There is no SI equivalent; use the dimensionless constant 1 in place of go in SI computations.)

{gp¡ = set of fluid properties associated with gas-handling phenomena

H = head of liquid column, ft (m) (Eq. 3); can also have the same meaning as the change in head AH (that is, the same meaning as "pump head").

AH = change in head across pump or pump stage, also called the "pump head" or "total dynamic head" ft (m).

AH = the small reduction in pump head (usually 3%) in testing for NPSHR, ft (m).

He = H,„ = the ideal head for an infinite number of blades that produce no blockage.

H = ideal head [= H + 2(HL)], ft (m) (Eq. 15b); sometimes called the "input head."

~EHl = all losses in the main flow passages from pump inlet to pump outlet, ft (m).

h = static enthalpy in Btu/lbm times goJ, ft2/sec2; (or in kcal/kg times J, m2/s2 = J/kg).

hsv or NPSH = net positive suction head, ft (m).

ID = inner diameter.

J = the mechanical equivalent of heat, 778 ft-lbf/Btu (4184 N-m/kcal).

m = distance in streamwise direction in meridional plane (Figure 14), in or ft (m).

MCSF or Qmin = minimum continuous stable flow, ft3/sec (m3/s).

N or n = rotative speed of the impeller, rpm. NPSH or hsv = net positive suction head, ft (m).

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