High-purity water procurement
RO + EDI quotation checklist
Define the water quality your process needs, where it will be verified and how much water must reach the use points. Then agree the equipment, storage, distribution and site scope.
A requirement such as “ultrapure water” or “include EDI” is not enough to define a complete system. State the actual specification and the sampling or measurement location.
Information to prepare · Adding EDI to existing RO · Compare supply scope · Copy a project brief
Seven information groups for your enquiry
Keep raw-water results, existing RO permeate results and final-water requirements separate. Include the original units and identify unknown items as to be confirmed.
1. Production process and water quality
Describe the process using the water. Send the applicable specification, required parameters, measurement temperature or temperature-compensation conditions, and the location where compliance is required.
A conductivity or resistivity value does not establish that every other water-quality requirement is satisfied.
2. Source-water analysis
Identify the source, sampling date and location. Send the original results with units, describe known variations, and list separate sources separately.
3. Demand and operating schedule
State required hourly flow, daily volume, peak simultaneous use, peak duration and production shifts. This helps review generation, storage and distribution together.
4. Existing RO equipment
For an EDI addition, provide the current RO configuration, permeate analysis, operating records and known problems. Identify where the RO permeate sample was taken.
5. Storage and distribution
Describe existing tanks, pipework materials, distances, use points and any circulation arrangement. Supply available drawings and identify equipment to retain.
6. Site and utilities
Give the project country and city, voltage, frequency, phase, available space and drainage conditions. Identify the team responsible for site pipework and electrical connections.
7. Delivery and acceptance
State the intended start-up date, installation responsibility, sampling points, test methods and acceptance documents. Agree what is included in transport, installation, commissioning, operator training, testing and subsequent support.
Can EDI simply be added after an existing RO unit?
Review the actual permeate and the proposed module’s feed requirements first. Conductivity alone does not fully describe the ionic load that an EDI system must handle.
DuPont’s EDI-310 technical manual discusses feedwater conductivity alongside carbon dioxide, total hardness and dissolved silica. This provides a reference for what to investigate; it does not establish which module a Qingze project will use or make its limits universal. Apply the current requirements of the selected module to the actual project.
Technical reference: DuPont EDI-310 Technical Manual, Rev. 2, June 2025, section 4.1 (PDF).
Project example: separate each stage’s capacity
The Hubei high-purity water project used municipal water and a serial treatment route: first-pass RO at 25 m³/h, second-pass RO at 20 m³/h and EDI at 20 m³/h. These stage capacities are not added together as 65 m³/h of final supply.
The recorded 18.2 MΩ·cm value was the project’s product-water requirement. It is not an acceptance-test measurement published here, or a guarantee for another system.
The project also included nitrogen-blanketed storage, variable-frequency transfer, polishing and terminal treatment. Qingze’s scope for this project included equipment production, transport, site installation, commissioning and training. Confirm the scope separately for a different site.
Compare proposals at the same boundaries
- Capacity at each stage: distinguish RO stages, EDI output and final delivery to production. State the applicable operating conditions.
- Acceptance location: identify measurements at the main unit, after storage or circulation, and at production use points. Agree methods and conditions.
- Included equipment: list pretreatment, RO, EDI, tanks, transfer or circulation, terminal treatment, controls and instruments individually.
- Site responsibilities: identify who supplies transport, piping, electrical work, installation, commissioning, training, testing and support.
Two proposals both labelled “two-pass RO + EDI” may cover different storage, circulation, monitoring and site work.
Copy this brief and fill in what you know
Production process using the water:
Required quality, units and measurement conditions:
Required acceptance or sampling location:
Hourly / daily demand, peaks and shifts:
Water source and available analysis:
Existing RO equipment and permeate information:
Storage, circulation, pipework and use points:
Electrical supply, space and drainage:
Target start-up date:
Equipment and site services to include:
Details still to be confirmed:
Start with the information available. Do not borrow another factory’s quality target or treat a single instrument reading as proof of every requirement.
Discuss your high-purity water requirements
Review Qingze RO + EDI systems · Electronics application planning