How to use DEHA？

DEHA is an oxygen scavenger and metal passivator widely used in boiler feedwater, cooling systems, and industrial processes to prevent corrosion by removing dissolved oxygen (O₂) and forming protective magnetite (Fe₃O₄) layers on metal surfaces.

1. Key Properties of DEHA

Chemical Formula: (C₂H₅)₂NOH

Appearance: Colorless to pale yellow liquid (typically supplied as 85–95% active solution).

Mechanism:

Oxygen scavenging: Reacts rapidly with dissolved O₂ to form water and harmless byproducts.

Metal passivation: Promotes formation of a protective magnetite layer on steel surfaces.

Degradation: Breaks down into diethylamine (DEA) and acetic acid, which are volatile.

2. Application Methods

(1) Dosage Recommendations

Application Dosage (Active DEHA) Notes

Boiler Feedwater 0.5–5 ppm per 1 ppm O₂ Continuous injection

Cooling Water 5–20 ppm (shock dose) Periodic treatment

Closed Heating Systems 10–50 ppm (initial dose) Follow with 2–10 ppm maintenance

Decorative Fountains 5–15 ppm Prevents green stains from copper corrosion

Note:

Oxygen removal efficiency: 1 ppm DEHA removes ~0.25 ppm O₂.

Higher doses may be needed in systems with high oxygen ingress (e.g., leaks, makeup water).

(2) Injection Points

Boilers: Inject into the deaerator storage tank or feedwater line (before the economizer).

Cooling Systems: Add to the suction side of the pump for even distribution.

Closed Loops: Use a metering pump for continuous treatment.

(3) Compatibility

Works well with amine-based pH adjusters (e.g., cyclohexylamine, morpholine).

Do not mix with oxidizing biocides (e.g., chlorine, bromine) → neutralizes DEHA.

Compatible with phosphates and polymers used for scale control.

3. Advantages & Limitations

✔ Advantages

Fast oxygen scavenging (faster than sulfite in high-temperature boilers).

Low solids formation (unlike sulfite, which produces sulfate salts).

Passivates metal surfaces (reduces long-term corrosion).

Volatile (does not accumulate in steam systems).

✖ Limitations

Less effective in low-temperature systems (<100°C / 212°F).

Not suitable for potable water (forms diethylamine, which is regulated).

Higher cost compared to sulfite-based scavengers.

4. Safety & Handling

Storage: Keep in a cool, dry, ventilated area; avoid contact with oxidizers.

PPE: Wear gloves & goggles (can cause mild skin/eye irritation).

Environmental Impact: Breaks down into biodegradable byproducts (low toxicity).

5. Monitoring & Optimization

Test residual DEHA (via HPLC or colorimetric methods).

Monitor oxygen levels (should be <5 ppb in boilers).

Adjust dosage based on system conditions (e.g., leaks, temperature changes).

Summary of Best Practices

Inject continuously in boilers for optimal O₂ removal.

Combine with pH control (e.g., amines) for enhanced corrosion protection.

Avoid mixing with oxidizers (chlorine, hydrogen peroxide).

Use higher doses in new systems to passivate metal surfaces quickly.

For specific system requirements, consult the manufacturer’s technical data sheet (TDS).