Quick-Pick by System
| System Type | Scale Risk | Corrosion Risk | Primary Inhibitor | Corrosion Inhibitor | Metal Deactivator |
|---|---|---|---|---|---|
| Open Recirculating Cooling Water (carbon steel) | CaCO₃, CaSO₄ | General corrosion | HEDP 10–30 ppm | Zinc phosphate 2–5 ppm Zn²⁺ | — |
| Open Recirculating Cooling Water (copper alloys present) | CaCO₃, CaSO₄ | Pitting + galvanic | PBTCA 5–15 ppm | Zinc phosphate 1–3 ppm Zn²⁺ | BTA 1–3 ppm |
| Once-Through Cooling Water | CaCO₃ (mild) | Low — short residence | HEDP 2–8 ppm | — | — |
| Low-Pressure Boiler (<10 bar) | CaSO₄, silica | Oxygen corrosion | HEDP or ATMP 5–20 ppm | Sodium molybdate 50–200 ppm | — |
| Medium-Pressure Boiler (10–60 bar) | Silica, magnetite | CO₂ + O₂ corrosion | Phosphate alkalinity control | Sodium sulfite or DEHA (oxygen scavenger) | — |
| Closed Cooling Loop (chiller circuit) | Low — no evap | Galvanic + crevice | HPMA dispersant 50–100 ppm | Sodium nitrite 500–1500 ppm or molybdate 200–500 ppm | BTA 10–30 ppm |
| District Heating / Hot Water Loop | Low | Oxygen ingress corrosion | — | Sodium molybdate 200–500 ppm or nitrite | BTA 5–20 ppm |
| Desalination Concentrate System | CaSO₄, BaSO₄ | Low pH corrosion | ATMP 5–15 ppm + HEDP 5–10 ppm | — | — |
All Grades (by chemistry class)
Phosphonate Scale Inhibitors — HEDP, ATMP, PBTCA, HPMA(4)
The workhorses of modern scale inhibition. Phosphonates chelate calcium and magnesium ions at the crystal nucleation stage (threshold effect), preventing CaCO₃ and CaSO₄ scale from forming at doses 100–1000× below stoichiometric. HEDP is the all-rounder; ATMP excels at silica and calcium phosphate inhibition; PBTCA provides combined scale + mild corrosion inhibition; HPMA (polymaleic acid) is a dispersant-grade polymer for particulate suspension.
scale inhibitors
HEDP (1-Hydroxyethylidene-1,1-Diphosphonic Acid)
CAS: 2809-21-4
Organophosphonic acid scale and corrosion inhibitor for cooling water, boiler water and oilfield systems. Effective against CaCO3 and BaSO4 scale at low dosage.
View Details →scale inhibitors
ATMP (Amino Trimethylene Phosphonic Acid)
CAS: 6419-19-8
Nitrogen-containing phosphonic acid with excellent CaCO3 and CaSO4 scale inhibition. Better calcium tolerance than HEDP in high-hardness systems.
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PBTCA (2-Phosphonobutane-1,2,4-Tricarboxylic Acid)
CAS: 37971-36-1
Chlorine-stable phosphonate scale inhibitor that maintains performance in chlorinated cooling water systems. Unlike HEDP/ATMP, PBTCA is not degraded by oxidizing biocides.
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HPMA (Hydrolyzed Polymaleic Anhydride)
CAS: 26099-09-2
Phosphorus-free polymer scale inhibitor and dispersant. Environmentally preferred alternative to phosphonate-based inhibitors in discharge-sensitive applications.
View Details →Metal Deactivators — Benzotriazole (BTA), Tolyltriazole (TTA)(2)
Azole-type copper and copper-alloy corrosion inhibitors. BTA (benzotriazole) and TTA (tolyltriazole / methylbenzotriazole) form a chemisorbed monomolecular film on copper, brass, and bronze surfaces, reducing corrosion rate from ~200 μm/year to <5 μm/year. Essential in systems containing brass heat exchangers or copper tube condensers. TTA has slightly better thermal stability than BTA above 80°C.
corrosion inhibitors
Benzotriazole (BTA)
CAS: 95-14-7
Copper and copper-alloy corrosion inhibitor forming a stable protective film. Essential additive in cooling water, metalworking fluids and antifreeze formulations.
View Details →corrosion inhibitors
Tolyltriazole (TTA)
CAS: 29385-43-1
Methyl-substituted benzotriazole with improved solubility and better chlorine resistance. Preferred copper inhibitor in chlorinated cooling water systems.
View Details →Anodic Corrosion Inhibitors — Sodium Molybdate, Sodium Nitrite(2)
Anodic inhibitors passivate the metal surface by forming a stable protective oxide layer at anodic sites. Sodium molybdate (Na₂MoO₄) is the premium choice for closed-loop and mixed-metallurgy systems — non-toxic, synergistic with zinc and phosphate, effective 50–500 ppm range. Sodium nitrite is the workhorse for closed cooling loops at 500–2000 ppm but requires biocide co-dosing to prevent nitrite-consuming bacterial growth.
corrosion inhibitors
Sodium Molybdate Corrosion Inhibitor
CAS: 7631-95-0
Non-toxic molybdate-based anodic corrosion inhibitor for closed-loop cooling and heating systems. Environmentally preferred alternative to chromate inhibitors.
View Details →corrosion inhibitors
Sodium Nitrite Corrosion Inhibitor
CAS: 7632-00-0
Anodic passivating corrosion inhibitor for closed-loop systems and hydrostatic testing. Forms iron oxide passive film on steel surfaces.
View Details →Cathodic / Mixed Inhibitors — Zinc Sulfate, Zinc Phosphate, Sodium Gluconate(3)
Zinc ions precipitate as Zn(OH)₂ at cathodic sites, suppressing cathodic reduction reactions and limiting general corrosion. Zinc phosphate combines the cathodic zinc mechanism with phosphate anodic passivation — the most widely used corrosion inhibitor for open cooling systems. Sodium gluconate acts as both a chelant and cathodic inhibitor, especially in hard-water high-pH systems where zinc would precipitate.
corrosion inhibitors
Zinc Sulfate Corrosion Inhibitor Grade
CAS: 7733-02-0
Zinc-based cathodic corrosion inhibitor for open recirculating cooling water. Works synergistically with phosphonates and phosphates to form zinc-phosphate protective film.
View Details →scale inhibitors
Zinc Phosphate Corrosion & Scale Inhibitor
Combined zinc-phosphate formulation for simultaneous corrosion and scale control in open recirculating cooling water systems. Forms protective film on metal surfaces.
View Details →corrosion inhibitors
Sodium Gluconate (Corrosion & Scale Inhibitor)
CAS: 527-07-1
Biodegradable chelating agent and corrosion inhibitor for alkaline cleaning and water treatment. Green alternative to EDTA and NTA in environmentally sensitive applications.
View Details →Imported Brand → China Equivalent
Equivalents are indicative; verify against TDS for project-critical applications.
| International Brand / Grade | China Equivalent | Major Chinese Producers |
|---|---|---|
| Dow Dequest 2010 (HEDP 60%) | HEDP 60% liquid (GB/T 15894) | 淄博万昌 (Wanchang), 郑州鑫恒, 广州昊诺 |
| Dow Dequest 2006 (ATMP 50%) | ATMP 50% liquid | 淄博万昌, 武汉远城, 郑州鑫恒 |
| Dow Dequest 2066 (PBTCA 50%) | PBTCA 50% liquid | 淄博万昌, 郑州鑫恒, 上海赛默 |
| Albemarle Aquatreat AR-540 (HPMA) | HPMA 50% dispersant polymer | 郑州鑫恒, 上海赛默, 广州昊诺 |
| ICL BK-310 (BTA powder 99%) | BTA 99% powder (GB/T 2978) | 武汉远城, 南通精化, 上海精美 |
| Vanderbilt Cuvan 826 (TTA 50% liquid) | TTA (MBT) 50% solution | 武汉远城, 南通精化, 广州昊诺 |
| ICL Sodium Molybdate 39.5% | Sodium Molybdate 39% liquid | 九江格兰特, 武汉远城, 郑州鑫恒 |
| Chemours (DuPont) MOLY 2067 program | Molybdate + BTA closed-loop program | 郑州鑫恒配方产品, AQUChem 预配方 |
| Enthone Corrshield NT (zinc phosphate program) | Zinc phosphate + HEDP open cooling program | 淄博万昌, AQUChem 预配方 |
| Buckman Busan 11-M1 (sodium nitrite closed loop) | Sodium Nitrite 40% inhibitor + BTA | AQUChem 预配方 |
Frequently Asked Questions
▶HEDP vs ATMP vs PBTCA — which phosphonate should I use?
HEDP for general CaCO₃ scale in cooling water and low-pressure boilers; ATMP for high-silica or calcium phosphate scale; PBTCA when you want combined scale inhibition plus mild carbon-steel corrosion protection in a single molecule.
HEDP vs ATMP vs PBTCA — which phosphonate should I use?
HEDP for general CaCO₃ scale in cooling water and low-pressure boilers; ATMP for high-silica or calcium phosphate scale; PBTCA when you want combined scale inhibition plus mild carbon-steel corrosion protection in a single molecule.
▶Zinc phosphate vs molybdate vs nitrite — which corrosion inhibitor for my system?
Zinc phosphate for open cooling towers with carbon steel (cost-effective, widely accepted); molybdate for closed loops and mixed-metallurgy systems (non-toxic, no environmental issues); sodium nitrite for closed hot-water loops where molybdate cost is prohibitive (but mandates biocide co-treatment to prevent Nitrobacter).
Zinc phosphate vs molybdate vs nitrite — which corrosion inhibitor for my system?
Zinc phosphate for open cooling towers with carbon steel (cost-effective, widely accepted); molybdate for closed loops and mixed-metallurgy systems (non-toxic, no environmental issues); sodium nitrite for closed hot-water loops where molybdate cost is prohibitive (but mandates biocide co-treatment to prevent Nitrobacter).
▶What is cycles of concentration and how does it affect inhibitor dosing?
Cycles of concentration (COC) measures how much the dissolved salts have concentrated vs makeup water. Higher COC = less blowdown water = better water efficiency, but increases scale and corrosion risk. Inhibitor programs must be tuned to the target COC (typically 3–6 for most towers).
What is cycles of concentration and how does it affect inhibitor dosing?
Cycles of concentration (COC) measures how much the dissolved salts have concentrated vs makeup water. Higher COC = less blowdown water = better water efficiency, but increases scale and corrosion risk. Inhibitor programs must be tuned to the target COC (typically 3–6 for most towers).
▶What are the environmental and regulatory constraints on phosphonate and zinc discharge?
EU IED and many national regulations limit total phosphorus in cooling-tower blowdown to 1–2 mg/L P and zinc to 0.3–1 mg/L Zn. This drives shifts from zinc-phosphonate programs to zinc-free molybdate or all-organic polymer programs in environmentally sensitive sites.
What are the environmental and regulatory constraints on phosphonate and zinc discharge?
EU IED and many national regulations limit total phosphorus in cooling-tower blowdown to 1–2 mg/L P and zinc to 0.3–1 mg/L Zn. This drives shifts from zinc-phosphonate programs to zinc-free molybdate or all-organic polymer programs in environmentally sensitive sites.
▶How do I monitor scale and corrosion inhibitor performance on-site?
Use corrosion coupons (mild steel + copper, 30-day exposure, target <5 mpy carbon steel / <1 mpy copper), deposit coupons, and monthly water analysis (calcium, M-alkalinity, silica, phosphonate residual, pH, conductivity, Zn if used).
How do I monitor scale and corrosion inhibitor performance on-site?
Use corrosion coupons (mild steel + copper, 30-day exposure, target <5 mpy carbon steel / <1 mpy copper), deposit coupons, and monthly water analysis (calcium, M-alkalinity, silica, phosphonate residual, pH, conductivity, Zn if used).