Versatility of the Gradient Colors Feature in PIPE-FLO® Professional

By Jeff Sines, Senior Product Engineer

PIPE-FLO®  Professional is an excellent tool to model complex piping systems commonly found in many industries, including chilled water and ultra-pure water systems used in data centers, manufacturing, chemical processing, HVAC, pharmaceutical, and other industrial and commercial facilities. The intuitive user interface makes it easy to quickly model these complex systems.  PIPE-FLO® then performs a hydraulic analysis, generates messages, and displays calculated results for the user to evaluate.

The Gradient Colors feature in PIPE-FLO®  allows the user to view the piping system from different perspectives at various times in the modeling process. It is critical to enter correct design data in the model in order to obtain and present the most accurate results. The Gradient Colors feature in PIPE-FLO® helps the user by identifying costly design flaws and operational issues in your model prior to implementation.

Starting in version 16.1 (released in January 2018), the Gradient Color Legend was added to the FLO-Sheet Reports, allowing the user to print the colorized piping diagram along with the color legend for the selected criteria and the range of values colorized and the range of the calculated values.

Using Gradient Colors for Presentation Value

For some projects, the engineer who modeled a large piping system may need to make a presentation to co-workers, management, or to their customers. A presentation may be needed to justify the cost of an optimization project, explain a complex hydraulic problem, or evaluate a proposed solution to a problem. Including an eye-catching colorized image of the PIPE-FLO® model is a good way to add value to the presentation. 

As an example, let’s say a major Cloud company is evaluating an expansion of their Data Center Chilled Water System. The goal is to double their number of data center storage servers over the next several years. Cooling these servers is critical to operations as the SLA requirements include 100% uptime with full redundancy. The existing cooling system can be modeled using PIPE-FLO® Professional and the expected performance evaluated prior to making costly modifications. The value of using PIPE-FLO® in presenting the recommendations for change is that the model is colorized  to make it extremely easy to show the current environment and understand the pressure distribution throughout system as shown.

Using Gradient Colors While Building the Piping System Model

In PIPE-FLO® Professional, the Gradient Colors window allows you to set Criteria, Range, and Colors to colorize the model. The default criterion is set to “None” so that the severity level of any message generated by the hydraulic analysis determines the color of the devices. Additional criterion are used to colorize the model based on various design data or calculated results. Design data criteria include Elevation, Fluid Temperature, Pipe Length, and Pipe Size.  Key calculated results include Flow Rate, Head Loss, Pressure, Pressure Drop, Reynolds Number, and Velocity.

During the initial modeling of a piping system, mistakes are made while entering the elevation, length, size, fluid zone, or other design data. These mistakes reduce the accuracy of the calculated results and they cause unexpected messages that take time to understand the cause of the error.

For example, in the model of the Data Center Chilled Water System, supply lines provide cold chilled water to the air handlers (A/H) that heat up the water. Warm water is returned to the primary pumps and chillers. The copy/paste and group editing features of PIPE-FLO® allow for the rapid development of the model, but occasionally mistakes are made when assigning the Fluid Zone to the pipelines.

You can easily set the Gradient Colors Criteria to “Fluid Temperature” and quickly see which pipes have the wrong Fluid Zone assigned, as shown below.

Using Gradient Colors to Evaluate Calculated Results

Colorizing the model by key calculated results allows the engineer to focus on various aspects of the system, including finding bottlenecks, potential areas for cavitation, and the location of the critical path load, sometimes referred to as the most hydraulically remote load.

When evaluating the expansion of the Data Center Chilled Water System, some portion of the system will be the most restrictive and present a bottleneck that may effect whether the system will be able to deliver the required flow rate to each air handler. Evaluating the fluid velocity is one way to find this bottleneck.

By modeling the expansion, then colorizing the system by the Velocity criteria, the locations of high velocity can be quickly identified. A minimum velocity of 7 feet/sec is specified in the Range to colorize only those pipes with a velocity greater than that, allowing the locations of the bottlenecks to really stand out.

Once the locations and causes of the bottlenecks are found, a determination can be made to de-bottleneck the modified system,  perhaps by increasing the pipe size, installing headers in parallel, or by considering a different location to connect the expansion to the current configuration. 

Displaying the Color Gradient Legend on the FLO-Sheet Report

Starting in version 16.1, the Gradient Color Legend was added to the FLO-Sheet Reports, allowing the user to print the colorized piping diagram along with the color legend for the selected criteria and the range of values colorized and the range of the calculated values.

To generate the report with the legend, go to the File Menu, select Print, then select one of the FLO-Sheet Reports with the Color Legend.


When evaluating the design and operation of a piping system, engineers often need to view the performance from different perspectives in order to fully understand how it is truly operating. The Gradient Colors feature in PIPE-FLO® Professional allows users to visually review how flow rates, pressures, pressure drops, head losses, elevations, and other parameters are distributed throughout the system. With PIPE-FLO® Professional’s intuitive user interface, engineers are able to model complex systems to support mission critical applications found in a wide range of industrial and commercial facilities such as data centers, manufacturing, chemical processing, HVAC, pharmaceutical and power generation.