Pump Intake Design ANSI HI 9.8: 1998.pdf !!BETTER!!
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How to Design a Pump Intake According to ANSI/HI 9.8-1998 Standard
A pump intake is the part of a pump system that receives the liquid from the source and delivers it to the pump. The design of a pump intake can affect the performance, efficiency, reliability and safety of the pump. Therefore, it is important to follow some guidelines and standards when designing a pump intake.
One of the most widely used standards for pump intake design is the ANSI/HI 9.8-1998 American National Standard for Pump Intake Design, published by the Hydraulic Institute. This standard provides recommendations and criteria for the design of pump intakes for various types of pumps and applications, such as vertical, horizontal, submersible, can-type and sump pumps.
The main objectives of the ANSI/HI 9.8-1998 standard are to:
Prevent or minimize flow disturbances and losses at the pump intake
Prevent or minimize air entrainment and vortex formation at the pump intake
Prevent or minimize cavitation and noise at the pump intake
Ensure adequate submergence and NPSH for the pump
Ensure uniform and stable flow distribution to the pump
Ensure adequate structural strength and durability of the pump intake
The ANSI/HI 9.8-1998 standard covers various aspects of pump intake design, such as:
Pump intake geometry and dimensions
Pump intake location and orientation
Pump intake approach flow conditions
Pump intake inlet bell design
Pump intake submergence requirements
Pump intake model testing
Pump intake remedial measures
The ANSI/HI 9.8-1998 standard also provides examples, figures, tables and appendices to illustrate and explain the design criteria and recommendations. The standard is intended to be used by engineers, designers, contractors, owners and operators of pump systems.
To access the full version of the ANSI/HI 9.8-1998 standard, you can purchase it from the Hydraulic Institute website or from the American National Standards Institute website.
Pump Intake Design Examples
To illustrate the application of the ANSI/HI 9.8-1998 standard, let us consider some examples of pump intake design for different types of pumps and situations.
Example 1: Vertical Pump Intake in a Wet Well
A vertical pump is installed in a wet well to pump wastewater from a sewer system. The pump has a rated flow of 500 gpm and a suction pipe diameter of 8 inches. The wet well has a rectangular cross-section with dimensions of 10 ft x 10 ft. The pump inlet bell is located at the center of the wet well floor. The minimum liquid level in the wet well is 5 ft above the floor.
Using the ANSI/HI 9.8-1998 standard, we can calculate the following design parameters for the pump intake:
Bell mouth width (D) = 1.5 x 8 inches = 12 inches
End wall clearance (B) = 0.75D = 0.75 x 12 inches = 9 inches
Centreline spacing (a) = 2.5D = 2.5 x 12 inches = 30 inches (not applicable for single pump)
Bell mouth floor clearance (C) = 0.3D to 0.5D = 0.3 x 12 inches to 0.5 x 12 inches = 3.6 inches to 6 inches
Minimum submergence (S) = D (1 + 2.3 FD) = 12 inches (1 + 2.3 x 0.1) = 15.36 inches (assuming FD = 0.1 for wastewater)
Minimum tank width (A) = 5D = 5 x 12 inches = 60 inches
Minimum liquid depth (H) = S + C = 15.36 inches + 6 inches = 21.36 inches
The angle of floor slope (Î) = not required for vertical pumps
The above parameters ensure that the pump intake meets the criteria of the ANSI/HI 9.8-1998 standard and avoids flow disturbances, air entrainment, vortices and cavitation.
Example 2: Horizontal Pump Intake in a Canal
A horizontal pump is installed in a canal to pump irrigation water from a river. The pump has a rated flow of 1000 gpm and a suction pipe diameter of 10 inches. The canal has a trapezoidal cross-section with a bottom width of 15 ft, a top width of 20 ft and a depth of 10 ft. The pump inlet bell is located at one side of the canal bottom, parallel to the flow direction. The minimum water level in the canal is 8 ft above the bottom.
Using the ANSI/HI 9.8-1998 standard, we can calculate the following design parameters for the pump intake:
Bell mouth width (D) = 1.5 x 10 inches = 15 inches
End wall clearance (B) = not applicable for open channel flow
Centreline spacing (a) = not applicable for single pump
Bell mouth floor clearance (C) = not applicable for open channel flow
Minimum submergence (S) = D (1 + FD) = D (1 + V/gD) = D (1 + V/32.2D), where V is the approach velocity in ft/s and g is the gravitational acceleration in ft/s
Minimum tank width (A) = not applicable for open channel flow
Minimum liquid depth (H) = S + C + D/2 + hs, where hs is the suction head loss in ft
The angle of floor slope (Î) = not required for horizontal pumps
To calculate S and H, we need to estimate V and hs. Assuming a uniform flow in the canal with a discharge of 061ffe29dd