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INITIAL APPLICATION DATASHEET FOR THE CONSULTING REQUEST

(remember to indicate proper units, such as: 20 gpm, 60 psiG, 80 deg. F, etc.)

Your Name:

Company:

Country and State:

E-mail:

Pumped Fluid:

Flow:

Discharge Pressure:

Suction Pressure:

Differential Pressure:

Specific Gravity:

Temperature:

Viscosity:

Vapor Pressure:

pH:

% Solids and their Size:

Preferred Materials of Construction:

Any additional comments?

 

EXAMPLE:

Pumped Fluid sulfuric acid, 93%
Flow 120 gpm
Discharge Pressure 70 psi
Suction Pressure 10 psig
Differential Pressure (60 psi)
Specific Gravity 1.4
Differential Head  
Temperature 80 deg. F
Viscosity 20-30 cP
Vapor Pressure  
pH 3-4
% Solids and Size none (clean)
Preferred Materials of Construction please recommend
Comments ANSI preferred

Several different pump types can be selected. Since the viscosity is low, an an ANSI design was preferred, a centrifugal pump would normally be a first candidate. Since differential head was not given, it is calculated from the differential pressure as:

H = delta_p x 2.31 / SG = 98 feet

An ANSI centrifugal pump 1.5" x 1" x 6" could be used (1.5" suction, 1" discharge). The impeller size, based on the differential head, would be approximately 5.8", at 3600 rpm (for 50 cycle systems it would be different). Pump efficiency, based on the curve, is approximately 70%.

To estimate a motor requirement, the pump horsepower needs to be calculated: 

BHP = (H x Q x SG) / (3960 x eff) = (98 x 120 x 1.4) / (3960 x 0.70) = 6.1 hp - this is a first approximation, and would have to be corrected for viscosity, seal losses (or, if a mag-drive, eddy-current losses), as well as possibly adding a pump-run-out operation margin. 

Note: the information about the discharge pressure was incomplete! It stated "70 psi", without indicating gage (psig), or absolute (psia) units. The "gage" units were assumed, as indirectly implied by the differential pressure.

NPSHA was not calculated, because vapor pressure was not given (for a NPSH information refer to an Articles section of Pump Magazine). Assumption was also made that there is plenty of available NPSHA. Otherwise, a larger pump, running slower might need to be considered.

Stainless steel construction should be sufficient for 93%-concentration sulfuric acid.

Pump prices vary depending on a manufacturer, but, as a rough estimate, such centrifugal Group I ANSI pump list price is around $3,000.