An incomplete Coanda screen specification (the data sheet you send with the RFQ) costs everyone time. The manufacturer asks clarifying questions. The engineer has to look up answers that should have been available at the start. The project schedule slips by a week before a single piece of steel is cut.
We see this repeatedly. A request for quotation (RFQ) arrives with a flow rate and a material grade, and nothing else. No water chemistry data, no site dimensions, no hydraulic head information, no environmental requirements. The specification looks complete to the person who wrote it, but it is missing the parameters that really determine the screen design.
This checklist eliminates that problem. It covers every parameter ADENCO needs to design, quote, and manufacture a Coanda intake screen, and it explains why each parameter matters so you can collect the right information from the right people before the RFQ is issued.
Table of Contents
- Before You Start: Prescriptive vs. Performance Specifications
- The 15-Parameter Specification Checklist
- The Five Most Common Specification Omissions
- Sample Specification Template
- How ADENCO Processes Your RFQ
- Frequently Asked Questions
- References
Before You Start: Prescriptive vs. Performance Specifications
There are two ways to specify a Coanda screen:
Prescriptive specification: You define the exact screen parameters: slot opening, screen width, material grade, tilt angle, wire profile. This approach works when you have your own hydraulic engineers and have already completed the design calculations.
Performance specification: You define the performance requirement (design flow rate, minimum filtration size, water chemistry, site constraints) and the manufacturer designs the screen to meet those requirements. This is the approach most engineers use, and it is what ADENCO recommends for projects where the client does not have prior Coanda screen design experience.
Either approach works. The checklist below covers both: providing the information needed whether you are stating exact parameters or defining performance requirements for ADENCO's engineering team to turn into a design.
The 15-Parameter Specification Checklist
Section A: Hydraulic Requirements
1. Design Flow Rate (l/s or m³/h)
The maximum flow of water the screen must deliver to the downstream system. This is the single most important parameter to state: it determines screen width.
Where to get it: From the hydraulic design of the downstream system: turbine rated flow, pump capacity, treatment plant design throughput, or irrigation demand.
Common error: Stating average flow instead of peak demand. The screen must deliver the maximum instantaneous demand, not the daily average. For sizing methodology, see: How to Size a Coanda Intake Screen.
2. Available Head (mm)
The vertical distance between the weir crest (where water enters the acceleration plate) and the base of the screen (where filtered water exits to the sump). The US Bureau of Reclamation (USBR) Coanda Design Guide (Wahl, 2003, report R-2003-03) gives 0.45 to 1.3 m as the typical range [1]; ADENCO's standard screens use 450, 700 and 1,270 mm, and custom screens can go higher.
Where to get it: From site survey: measure the elevation difference between the water surface at the intake and the invert (bottom level) of the downstream pipe, channel or sump.
Common error: Omitting the available head entirely. Without this measurement, ADENCO cannot confirm whether a Coanda screen is physically feasible at the site.
3. Minimum Filtration Size (mm)
The maximum particle size that may pass through the screen. This determines the slot opening.
Where to get it: From what the downstream system can tolerate: turbine nozzle orifice, emitter size, pump tolerance, or regulatory fish screening requirement. Typical values: 0.5 mm (narrow slot: Pelton turbines, drip irrigation pre-filter), 1.0 mm (standard slot: Francis turbines, municipal pre-filtration), 1.5–2.0 mm (wide slot: flood irrigation, general debris exclusion).
4. Safety Factor
ADENCO recommends a minimum safety factor of 1.3× for standard applications and 1.5× for critical applications (the only water supply, fish protection compliance, cold climate) [1]. State whether you want the screen sized at the design flow or with a safety factor applied.
Section B: Water Chemistry
5. Chloride Concentration (ppm)
The single most important parameter for material selection. It determines whether 304L, 316L, duplex, or a higher grade is required [2].
Where to get it: From a laboratory water analysis of the raw water. Critical: sample during worst-case conditions: typically late summer during low flow, when the chloride concentration is at its highest.
- <200 ppm → 304L
- 200–1,000 ppm → 316L
- 1,000–3,600 ppm → Duplex 2205
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3,600 ppm → Super-austenitic (consult ADENCO)
For the full material selection guide with PREN values, Critical Pitting Temperature data, and grade-variant explanations, see: 304 vs 316 Stainless Steel for Water Intake Screens.
6. pH Range
Acidic water (pH <6) accelerates corrosion and may require upgrading the material by one grade [2].
7. Water Temperature Range (°C)
Elevated temperature reduces corrosion resistance. If peak summer temperature exceeds 30°C, the material grade may need upgrading. If winter temperature approaches 0°C, anti-icing measures should be included [3].
8. Special Contaminants
Note any known presence of: iron above 0.3 mg/L (staining risk), manganese above 0.05 mg/L (deposit risk), hydrogen sulphide (corrosion risk), or free chlorine residual (if screened water contacts chlorinated return flows).
Section C: Site and Environmental
9. Application Type
Hydropower (state turbine type and hydraulic head), municipal drinking water, irrigation (state method), snowmaking, industrial process water, or other. The application determines ADENCO's design approach and any application-specific requirements.
10. Fish Protection Requirements
State the applicable regulation: US EPA 316(b), EU Water Framework Directive, UK Environment Agency screening guidance, UK Eels Regulations 2009, Australian state guidelines, or other. If no fish protection is required, state this explicitly: it affects slot opening selection and approach velocity design [4].
11. Cold Climate Measures
If the site experiences freezing temperatures, state:
- Minimum recorded air temperature at the site
- Whether anti-icing is required (electric heating, warm water recirculation, heated air diffuser)
- Whether thermal cycling from anti-icing systems affects the grade selection [3]
12. Flood Exposure
If the intake is in a floodplain or adjacent to a river subject to significant flood events, state the design flood recurrence interval (e.g., 1-in-100 year) and estimated flood velocity at the screen location. This determines structural design and anchor load capacities [5].
Section D: Physical and Installation
13. Available Weir Width (m)
The physical space available to install the screen panel(s). If the screen is being retrofitted to an existing weir, measure the usable width. If the weir is being built new, state the maximum width the concrete design allows.
14. Installation Type
- Permanent panel on weir (standard)
- Portable box screen (relocatable: common for agricultural and seasonal applications)
- Retrofit to existing structure (state existing weir dimensions, material, and condition)
- New-build (screen designed as part of new concrete works)
15. Delivery and Project Schedule
State the required delivery date and any project milestones that affect manufacturing scheduling. ADENCO's standard manufacturing lead time varies by screen size, complexity, and current production schedule: early contact allows us to align with your project schedule.
The Five Most Common Specification Omissions
Over hundreds of RFQs, these are the parameters most frequently missing, and the consequences of each omission:
| Omission | Why It Matters | Consequence If Missing |
|---|---|---|
| Water chemistry (chloride, pH, temperature) | Determines the material grade, which is the largest cost item | ADENCO cannot price the material. RFQ returned for additional information, adding 1–2 weeks. |
| Available head | Determines whether Coanda technology is feasible at the site | If the available head is insufficient (<450 mm), the entire screen concept may not work. Discovering this after procurement wastes everyone's time. |
| Fish protection regulation | Determines slot opening and may require approach velocity calculation | Non-compliant screen specification leads to permit delays or required screen replacement after installation. |
| Peak vs. average flow | Determines screen width | Undersized screen cannot deliver peak demand. Over-reliance on average flow is the most common sizing error. |
| Cold climate data | Determines anti-icing requirements and material grade selection | The screen is installed without anti-icing, blocks during the first winter ice event, and needs an emergency retrofit. |
For a detailed discussion of specification errors and their consequences, see: 5 Common Mistakes in Water Intake Screen Specification.
Sample Specification Template
Copy and complete the following for your RFQ. Fields marked * are required for ADENCO to provide a technical proposal and quotation.
COANDA INTAKE SCREEN: REQUEST FOR QUOTATION
PROJECT INFORMATION
Project name: _______________
Location (city/region/country): _______________
Application type*: _______________
Contact engineer: _______________
Email / phone: _______________
HYDRAULIC REQUIREMENTS
Design flow rate*: ___________ l/s
Peak flow rate (if different): ___________ l/s
Available head (weir crest to sump invert)*: ___________ mm
Required filtration size (max particle to pass)*: ___________ mm
Safety factor required: ___________ (default 1.3×)
WATER CHEMISTRY
Chloride concentration*: ___________ ppm
pH range: ___________
Water temperature range*: ___________ °C (min) to ___________ °C (max)
Iron content: ___________ mg/L
Manganese content: ___________ mg/L
Free chlorine residual (if applicable): ___________ ppm
Other contaminants: _______________
ENVIRONMENTAL REQUIREMENTS
Fish protection regulation (if applicable): _______________
Target species / life stage (if known): _______________
Minimum air temperature at site*: ___________ °C
Anti-icing required? Yes / No / To be determined
Flood recurrence interval (if applicable): _______________
Estimated flood velocity at screen (if known): ___________ m/s
PHYSICAL / INSTALLATION
Available weir width: ___________ m
Installation type: Permanent / Box screen / Retrofit / New-build
Existing weir dimensions (if retrofit): _______________
Preferred material grade (if known): _______________
DELIVERY
Required delivery date: _______________
Project milestone dates: _______________
ADDITIONAL NOTES
_______________________________________________
_______________________________________________
Submit this form to sales@coandaintakes.com or through the ADENCO contact form. ADENCO's engineering team will review and respond with a technical proposal and quotation within 1–2 business days for standard applications.
How ADENCO Processes Your RFQ
Once we receive a complete specification, here is what happens:
Step 1: Engineering Review (Day 1)
ADENCO's engineering team reviews your specification, confirms feasibility, and identifies any parameters that require clarification. If the specification is complete, we proceed directly to design.
Step 2: Hydraulic Design (Day 1–2)
We calculate the required screen width using your design flow, slot opening, available head, and site-specific adjustment factors. We select the wire profile, tilt angle, and acceleration plate geometry optimised for your conditions.
Step 3: Material Selection (Day 1–2)
Based on your water chemistry data, we select the stainless steel grade using our chloride/pH/temperature decision matrix. We compare the selection with PREN values and Critical Pitting Temperature data for your specific conditions [2].
Step 4: Technical Proposal and Quotation (Day 2)
You receive a complete technical proposal including: screen dimensions and configuration, material grade with justification, hydraulic performance data (design capacity, head loss), installation guidance, and a binding quotation with delivery time.
For complex projects (multi-panel arrays, unusual site constraints, or applications requiring detailed hydraulic modelling) the proposal may take 3–5 business days.
Step 5: Approval and Manufacturing
Upon approval, ADENCO manufactures the screen to the agreed specification. Each screen undergoes dimensional inspection and quality verification before dispatch. Standard screens are dispatched within the agreed lead time; we inform you of any change as soon as it is known.
Frequently Asked Questions
What should I include in a Coanda screen specification?
At minimum, include: design flow rate (l/s), available head (mm), required filtration size (mm), chloride concentration (ppm), water temperature range (°C), application type, and fish protection requirements (if any). These seven parameters allow ADENCO to produce a complete engineering design and quotation. The full 15-parameter checklist in this guide ensures nothing is missed and reduces the need for follow-up questions.
How do I write a Coanda screen specification for a public tender?
For tender specifications, we recommend a performance-based approach: define the performance requirements (flow rate, filtration size, water chemistry, regulatory compliance) rather than prescribing exact screen parameters. This allows manufacturers to propose optimised designs. Include the 15-parameter checklist as the minimum set of data, and require bidders to show that their design suits your water chemistry and meets your regulatory requirements. Cite the USBR Coanda Design Guide (Wahl, 2003, report R-2003-03) as the design standard for Coanda screens [1].
How quickly can I get a quote from ADENCO?
ADENCO provides technical proposals and quotations within 1–2 business days for standard applications when a complete specification is submitted. Complex projects (multi-panel arrays, unusual site constraints, detailed hydraulic modelling) may require 3–5 business days. Incomplete specifications add time: every missing parameter leads to a round of follow-up questions. Using the checklist in this guide ensures your RFQ has everything we need for a rapid response.
What if I do not have water chemistry data?
If a laboratory water analysis is not yet available, ADENCO can advise on the sampling protocol: what to test, when to sample (worst-case conditions), and which accredited laboratories serve your region. We can provide a preliminary quotation based on conservative assumptions (a higher material grade to allow for unknown chloride) and refine it when the water chemistry data is available. However, we strongly recommend obtaining a water analysis before finalising the specification. It is inexpensive and prevents the most common and costly material selection errors.
Can ADENCO help me write the specification?
Yes. ADENCO offers free technical consultations for engineers developing Coanda screen specifications. If you have the basic project parameters (flow rate, application, location) but are unsure about screen-specific details, contact our engineering team. We will help you develop a complete specification that meets your project requirements and can be used for competitive tendering if needed.
What design standard should I reference for Coanda screens?
The primary design reference is the USBR Coanda Design Guide (Wahl, 2003, report R-2003-03), published as Design Guidance for Coanda-Effect Screens by Tony Wahl [1]. This is the most comprehensive publicly available engineering guide for Coanda screen design and is freely downloadable from the U.S. Bureau of Reclamation website. For hydraulic performance calculations, cite Wahl (2001) in the Journal of Hydraulic Engineering [6] and Wahl et al. (2021) for updated surface tension data [7].
References
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Wahl, T.L. (2003). Design Guidance for Coanda-Effect Screens. U.S. Bureau of Reclamation, Research Report R-2003-03. Denver, CO. Retrieved from https://www.usbr.gov/tsc/techreferences/rec/R-2003-03.pdf
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"Susceptibility of Type 304/304L and 316/316L Austenitic Stainless Steels to Chlorides in Cooling Water." Digital Refining. Retrieved April 2026, from https://www.digitalrefining.com/article/1002873/
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"Performance of Coanda-Effect Screens in a Cold Climate." Journal of Cold Regions Engineering, Vol 28, No 4, ASCE, 2014.
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UK Environment Agency. "Screening for Intake and Outfalls: A Best Practice Guide." Retrieved April 2026, from https://assets.publishing.service.gov.uk/media/5a7c9293ed915d6969f45d2d/scho0205bioc-e-e.pdf
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World Bank / GFDRR (2019). Lifelines: The Resilient Infrastructure Opportunity. Retrieved April 2026, from https://openknowledge.worldbank.org/entities/publication/709788c9-b5e2-5190-8845-b757f33ac7d4
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Wahl, T.L. (2001). "Hydraulic Performance of Coanda-Effect Screens." Journal of Hydraulic Engineering, Vol 127, No 6. ASCE.
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Wahl, T.L. et al. (2021). "Surface Tension Effects on Discharge Capacity of Coanda-Effect Screens." Journal of Hydraulic Engineering, Vol 147, No 8. ASCE.
Published by ADENCO: Advanced Engineering Coanda Intake Screens. Complete the checklist above and send it to sales@coandaintakes.com. ADENCO's engineering team will return a technical proposal and a binding quotation within 1–2 business days. Free technical consultation available →