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Valves for Demineralised Water (DM Water / Deionised Water) Service

Demineralised water (DM water) is ultra-pure water with almost all dissolved minerals removed by ion exchange or reverse osmosis. It is used as boiler feedwater (BFW) in power plants and refineries, process water in pharmaceutical and semiconductor manufacturing, and as cooling tower make-up in critical systems. Its very low conductivity makes it unusually aggressive toward metals.

Pressure Range

3–120 bar (boiler feedwater up to drum pressure)

Temperature

Ambient to 250°C (boiler feedwater at operating temperature)

Industries

Thermal and nuclear power (boiler feedwater), Pharmaceutical API and formulation water, Semiconductor wafer fabrication

INDICATIVE ONLY - Reference DisclaimerDemineralised water for boiler feedwater service must comply with IBR requirements and the applicable boiler design standard. Pharmaceutical and semiconductor grade DM water systems have specific purity and material requirements under FDA 21 CFR, EU GMP, or SEMI standards. Vajra Industrial Solutions accepts no liability for material selection decisions based on this guide.

What valves are used for Demineralised Water (DM Water / Deionised Water) service?

Ball Valve (SS 316L, full-bore, PTFE seats) are recommended for Demineralised Water (DM Water / Deionised Water) service: Standard isolation and on/off service for DM water - zero contamination, low pressure drop..

Key Properties - Demineralised Water (DM Water / Deionised Water)

  • Very low conductivity (<0.5 μS/cm for high-purity grades) - highly aggressive to carbon steel
  • pH typically 6.5–8.5 (controlled by ammonia or morpholine dosing in boiler service)
  • No scale-forming minerals - allows operation at higher heat flux without fouling
  • Dissolved oxygen must be controlled (<7 ppb for high-pressure boiler BFW)
  • CO₂ absorption from atmosphere - can cause carbonic acid corrosion

Vajra Industrial Solutions manufactures and supplies valves for Demineralised Water (DM Water / Deionised Water) service — including ball valve (ss 316l, full-bore, ptfe seats) — in corrosion-appropriate materials selected for the operating conditions described here, with full material and test documentation.

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Material Compatibility - Demineralised Water (DM Water / Deionised Water)

Ratings are indicative. Actual compatibility depends on concentration, temperature, velocity, and presence of contaminants. Always consult corrosion tables or a materials engineer.

MaterialRatingNotes
Carbon Steel (WCB/A105)FairCorrodes rapidly in aggressive DM water. Acceptable only with pH control and oxygen scavenging.
SS 316LExcellentStandard material for DM water service - no iron contamination, corrosion-resistant.
SS 304 / 304LExcellentAcceptable for most DM water service; 316L preferred for hot or higher-purity applications.
Duplex SSExcellentOverkill for most DM service but used in pharmaceutical ultrapure systems.
PTFE-linedExcellentZero contamination - preferred for semiconductor and ultra-high purity DM water.
Bronze / brassPoorZinc dezincification and copper leaching - avoid for DM water where purity matters.

Recommended Valves

Ball Valve (SS 316L, full-bore, PTFE seats)

Standard isolation and on/off service for DM water - zero contamination, low pressure drop.

Full selection guide

Diaphragm Valve (SS 316L body, EPDM or PTFE diaphragm)

Preferred for pharmaceutical and semiconductor ultra-pure DM water - smooth bore, no dead leg.

Full selection guide

Globe Valve (SS 316L)

Flow control and throttling on DM water supply lines and chemical dosing.

Full selection guide

Check Valve (SS 316L piston or swing)

Pump discharge non-return - SS 316L to prevent iron contamination.

Full selection guide

Valves to Avoid

Cast iron or carbon steel bodies (iron contamination and rapid corrosion in aggressive DM water)

Bronze or brass valves (zinc/copper leaching into ultra-pure water)

Valves with dead legs or blind spots where stagnant DM water can concentrate corrosion

Special Considerations

Boiler feedwater (BFW): must meet specific dissolved oxygen limits - deaerator and chemical dosing required upstream of any carbon steel valves
IBR compliance required for any valves in steam-generating systems
Pharmaceutical and semiconductor: electropolished SS 316L internal surfaces, orbital welded joints, no dead legs - specify sanitary or bio-pharmaceutical valve standards (ASME BPE / EHEDG)
DM water storage: must be kept nitrogen-blanketed or in stainless tanks to prevent CO₂ absorption

Applicable Standards

ASME B16.34ASME B31.1 (power piping)ISPE Baseline Guide (pharmaceutical)

Shop Valves for Demineralised Water (DM Water / Deionised Water) Service

Other Fluid Services

Part of the Vajra Fluid Service Library

Demineralised Water (DM Water / Deionised Water) Service — Procurement & Specification

Typical Applications

Thermal and nuclear power (boiler feedwater)Pharmaceutical API and formulation waterSemiconductor wafer fabricationChemical synthesis solvent preparationFood and beverage process water

Available Standards

ASME B16.34ASME B31.1 (power piping)ISPE Baseline Guide (pharmaceutical)

Material Options

SS 316LSS 304 / 304LDuplex SSPTFE-lined

Documentation Available

  • -EN 10204 3.1 Material Test Certificates (heat traceable)
  • -API 598 hydrostatic shell & seat test reports
  • -Dimensional inspection reports
  • -Full Manufacturing Data Record (MDR) / data book on request
View documentation package

Inspection Options

  • -In-house QC inspection on every order
  • -Third-party inspection (SGS / Bureau Veritas / TÜV / DNV) coordination
  • -Witness and hold points accommodated on request
View inspection & testing

Order Quantities

Flexible — from single critical-spare valves to full project lots.

Export

Worldwide export with complete documentation (COO, EUR.1, packing lists) to 20+ countries.

Custom Engineering

Built to your specification — materials, trim, pressure class and special service (NACE, fire-safe, IBR, cryogenic).

Delivery Support

Dispatch from Vadodara, Gujarat with documented lead times and priority handling for urgent requirements.

Engineering references

Reviewed by Process Engineering, Vajra Industrial SolutionsDiscipline: Process & Fluid Service EngineeringLast reviewed: 20 June 2026

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