" />The Importance of Proper Piping Installation in UV Systems
Using ultraviolet (UV) light technology in water treatment is a widely accepted method of obtaining the safety and purity of drinking water. The United States Environmental Protection Agency (EPA) has issued the Ultraviolet Disinfection Guidance Manual (UVDGM). This provides technical information on applying UV light in public water systems. Many industrial entities, such as beverage manufacturers, aquatic facilities, and more, have adopted this manual to ensure the highest water quality standards.
However, with the growing use of UVDGM, there are questions from those unfamiliar with UV technology on the proper installation of UV systems. A critical element to consider in order to increase a UV system’s performance is the appropriate installation of upstream and downstream piping. In this article, we’ll look closer at the guidelines for piping installation as per the UVDGM.
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The UVDGM on Piping Installation
The UVDGM has specific language on installing upstream and downstream piping to ensure the delivery of an appropriate UV dose. The guidelines recommend the following options for conformity to the UVDGM.
- Minimum 5 Pipe Diameters of Straight Pipe Upstream of UV Reactor
The UVDGM requires a minimum of 5 pipe diameters of straight pipe upstream of each UV reactor. This length should equal the size of the straight line used in the validation testing plus an additional 5 pipe diameters. For example, if 24 inches of 4-inch diameter straight pipe was used during validation, then 44 inches of a straight line (24 inches + 5 pipe diameters * 4 inches) should be installed upstream of the UV reactor.
- Identical Inlet and Outlet Conditions
The UVDGM requires that the inlet and outlet conditions used during validation match those used at the treatment plant for at least 10 pipe diameters upstream and 5 pipe diameters downstream of the UV reactor.
- Velocity Profile Measurement
The UVDGM requires that the velocity of the water measured at evenly spaced points through a given cross-section of the flow upstream and downstream of the reactor is within 20 percent of the theoretical speed during the validation test stand and the treatment plant installation.
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The Right Choice for Your Application
The most effective option for a given application depends on: the specific site layout, piping constraints, and on how the validation was obtained.
Option 1 is the most widely used solution. On the other hand, option 2 requires a pipe layout from the UV system supplier and usually requires a Non-Disclosure Agreement (NDA) to be signed.
Option 3: The UV dose delivery is determined through computational fluid dynamics (CFD) modeling of inlet and outlet conditions.
Example of pipe layout from a validation report
The Critical Role of Pipe Layout
Pipe layout before and after the UV system is critical to achieve the desired performance. Improper piping installation can result in a 25% drop in performance. This can happen even if the UV system’s display indicates that it delivers the required dose and amount of mJ/cm2 inside the chamber.
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Working with an Experienced UV System Provider
- As the industrial market continues to adopt the UVDGM and 3rd party validation guidelines, working with an experienced UV system provider is essential.
- A provider that fully understands the guidelines and intricacies of 3rd party validations will ensure the UV system performs correctly and protects consumers and brand reputation.
Conclusion
- The UVDGM recommends installing upstream and downstream piping to achieve desired UV system performance.
- Considerations include a minimum of five pipe diameters of straight pipe upstream, identical inlet and outlet conditions, and velocity profile measurement.
- Pipe layout is critical for achieving desired performance and avoiding a drop in performance.
- It is crucial to work with an experienced UV system provider who understands the guidelines and intricacies of 3rd party validations to ensure the UV system performs correctly and protects consumers and the brand’s reputation.
Nuvonic
Date 13/08/2023
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