Instructions for using the utility to calculate pipe size according to flow rate

One of the most renowned methods of pipe sizing is using the Hazen-Williams equation, especially when the fluid involved is water.

Cong thuc chon ong
Cong thuc chon ong

The equation estimates the frictional loss (feet) for a specific pipe with Length, L (feet), Diameter, D (inch), Flowrate, Q (usgpm) and C-value: Hazen-Williams coefficient, C.

​The C-value of different materials of pipes can be referenced from various sources, which are summarized below. The higher the C-value, the “smoother” the flow in the pipe.

General Metal (Extremely smooth) - Ống kim loại tổng hợp cực nhẵn130
Cast Iron (CI) - Ống Gang100
Cast Iron Cement Lined (CICL) - Ống gang lót xi măng130
Cast Iron Bituminous Lined (CIBL) - Ống gang lót Bitum130
Cast Iron (Asphalt Coated) - Ống gang (phủ nhựa đường)100
Ductile Iron (DI) - ống gang dẻo110
Ductile Iron Cement Lined (DICL) - Ống gang dẻo lót xi măng130
Mild Steel (MS) - Ống thép nhẹ120
Mild Steel Cement Lined (MSCL) - Ống thép nhẹ lót xi măng130
Galvanised Iron (GI) - Ống sắt mạ kẽm120
Stainless steel - Ống inox140
Steel - Ống thép100
Steel (Corrugated) - Ống thép tole60
Copper (Cu) - Ống đồng140
Aluminium (Al) - Ống nhôm130
Brass (Br) - Ống thau130
Lead - Ống chì130
Tin - Ống thiếc130
Corrugated metal - Ống kim loại tole quấn60
Reinforced glass fibre (FRP) - Ống composite140
Plastic (General) - Ống nhựa tổng hợp130
High-density polyethylene (HDPE) - Ống HDPE150
Acrylonite Butadiene Styrene (ABS) - Ống nhựa ABS130
Polyethylene (PE) - Ống nhựa PE140
Polyvinyl chloride (PVC, CPVC) - Ống nhựa PVC, CPVC150
Spun Cement - Ống xi măng ly tâm130
Concrete - Ống bê tông100
Vitrified clay - Ống đất sét thuỷ tinh110
Wooden - Ống gỗ110
Masonry - Ống xây dựng110
Glass - Ống thủy tinh130

We can use the Hazen-Williams equation to estimate pipe sizes D, required for a given pipe C-value, flowrate Q, and the allowable frictional loss over a fixed 100 feet length of pipe (30m). This “ft/100ft or m/30m” maximum allowable friction loss is commonly set in the range within 4 to 10ft/100ft (1.2 to 3m). 4ft/100ft means that 4 feet of loss is the maximum that can be accepted in our design per 100 feet run of pipe. This value is then referred in a pipe size chart as shown below.

Instructions for using the pipe size calculation utility with images

Utility interface:

Water Pipe Size Calculator

Types of Pipe
C-Value of Pipe (Hazen-Williams coefficient)
Flowrate M3/H
Maximum Allowable Frictional Loss From 1,2 to 3,0. The smaller the pipe diameter, the higher this loss, value 1.2 is the average allowable value. m/30m dài
Min. Required Pipe Internal Diameter mm
Selected pipe size DN mm
Selected pipe size inch Inch
Water velocity in the pipe m/s

Input data

Step 1: Select the frame: Select the types of pipe, you need to choose the correct pipe material you are using to be able to access the corresponding C value. For example, choose stainless steel pipes

Step 2: Enter the water flow rate through the pipe, the unit is m3/h. For example, enter 20m3/h

Step 3: The maximum allowable friction loss frame, according to the above analysis, can be chosen in the range of 1,2-3,0. For example, choose 1,2


Step 4: Minimum required internal diameter to meet the flow rate with the selected loss. It is 67,05mm

Step 5: Suggest pipe diameter according to DN (mm). This recommendation for rounding up to even size is based on commonly available pipe sizes on the market. It is 80mm

Step 6: Suggest pipe diameter in Inches. This recommendation for rounding up to even size is based on commonly available pipe sizes on the market. It is 3inch

Step 7: Velocity of water flowing in the pipe in m/s, this value is appropriate in the range of 0,9-2,4. It is 1,1

Then the result will be as follows:

Pipe size
Pipe size

If you have questions about how to calculate pipe size, please contact our Company’s Sales department for more detailed instructions.

Leave a Reply

Your email address will not be published. Required fields are marked *