Antiscalant for RO plant — UN-307 phosphonate-blend chemistry for refinery feedwater
Programme outline, dosing range, feed points, target parameters, and lead times for the AAS antiscalant for ro plant into the refineries segment in Pakistan. Sole Pakistan agent for Shaanxi Ande Technology (China) and Innovative Water Technology (Pakistan). Karachi office, same-business-day technical response.
Same-day Karachi visit · CoA per drum · Engineering autopsy on request
UN-307 on a Mahmood Kot refining-sector RO train at 4 ppm dose: feed LSI +2.3, silica 42 mg/L. First-year silica fouling reduced 70% versus previous chemistry; autopsy confirmed scale-free membranes at 12 months.
Dosing programme outline
Programme outline below is the AAS default for refineries applications. Final dose is set against the customer's source-water analysis, equipment metallurgy, and operating cycles. Every drum ships with a Certificate of Analysis; SDS is shipped pre-shipment for HSE-document review.
- Product code
- UN-307
- Active chemistry
- Phosphonate blend (HEDP / PBTC) + polymeric dispersant
- Active content
- 40–50%
- Appearance
- Colourless to pale yellow liquid
- Density (25°C)
- ~1.20 g/cm³
- pH (1% solution)
- 2.0–4.0
- Typical dose
- 2–5 ppm on RO feed (as product)
- Max feedwater LSI
- +2.8
- Membrane compatibility
- Polyamide TFC / CPA / ESPA
- Drum / IBC
- 200 L drum, 1000 L IBC, bulk on tanker (contract)
- Lead time
- Ex-Karachi stock; 4–6 wks CIF on bulk
How a phosphonate antiscalant actually protects an RO membrane
An antiscalant for an RO plant does three jobs at once. Threshold inhibition — a low-dose phosphonate disrupts nucleation of CaCO₃, CaSO₄, BaSO₄, and SrSO₄ crystals before they form. Crystal modification — the phosphonate distorts the crystal lattice if nucleation does happen, preventing the crystal from adhering to the membrane surface. Dispersion — the polymeric component of UN-307 holds the modified crystals in suspension long enough to be flushed out in the concentrate. The dose window (2–5 ppm on feed) is set against the concentrate-side saturation indices, not against the feedwater LSI directly. A 2 ppm dose protects a brackish-water RO at LSI +1.5; a 5 ppm dose is needed on a refinery feed with LSI +2.3 and silica running 40 ppm reactive.
Where UN-307 wins on Pakistani RO plant feedwater
Pakistani RO plant feedwater carries scaling-index combinations that generic antiscalants do not handle. Indus-fed groundwater in Punjab pushes calcium and bicarbonate together — high LSI. Sindh-derived makeup from Korangi or Port Qasim runs high on sulphate plus barium — high CaSO₄ saturation plus BaSO₄ supersaturation. Mahmood Kot bores run silica into the 25–40 ppm reactive range. UN-307 is formulated with a polymeric dispersant component that holds silica supersaturation at the concentrate side — the failure mode that takes out a generic phosphonate antiscalant on these feedwaters within 6 months.
Dosing protocol: set against the concentrate side, not the feed
A common error in Pakistani RO operations is dosing antiscalant against the feedwater chemistry. The scaling risk lives on the concentrate side, where ions are concentrated 3–5× depending on recovery. The right protocol: pull a current feedwater analysis (TDS, Ca, Mg, alkalinity, SO₄, Si, Ba, Fe, pH), project concentrate-side ionic composition at the operating recovery, calculate LSI / S&DSI / silica saturation at the concentrate, and set the UN-307 dose against the maximum saturation index. AAS supplies the projection spreadsheet with the first programme order; the LSI/RSI Calculator at /calculators/lsi-rsi/ runs the feedwater-side numbers as a quick reference.
Compatibility with upstream and downstream chemistry
UN-307 dosing must sit downstream of any oxidising chemistry — chlorine, hypochlorite, peroxide — that the feedwater carries. The standard sequence is: oxidiser dosing for biofouling control (cooling-water side or well-head chlorination), then SMBS injection for dechlorination ahead of the cartridge filter (ORP-controlled to < +100 mV), then UN-307 injection at the cartridge-filter outlet, then the high-pressure pump and the membrane array. Polymeric dispersants in UN-307 are compatible with the standard cleaning chemistries (citric acid for inorganic scale, sodium-EDTA for metal-organic fouling, biodegradable surfactants for organic load) used during CIP.
What ships in the AAS UN-307 supply line
UN-307 ships in 200 L drums and 1000 L IBCs ex-Karachi for same-week dispatch. Bulk supply on tanker is available against a contracted multi-year volume; pricing improves with bulk commitment. The supply pack ships with COA per drum, MSDS pre-shipment, and a dose-calculation worksheet pre-filled against the customer's current feedwater analysis. Programme retainer covers quarterly feedwater retest, dose review, and 12-month membrane autopsy on a representative pressure-vessel coupon.
Questions procurement teams ask first.
What is the typical antiscalant dose on a Pakistani RO plant?
2–5 ppm of UN-307 on feed (as product, 40–50% active). The exact dose is set against concentrate-side saturation indices, not feedwater LSI alone. A 2 ppm starting dose covers a clean brackish feed; 4–5 ppm is needed on a refinery feed with silica > 25 ppm or LSI > +2.0.
Is UN-307 compatible with the standard RO membranes used in Pakistan?
Yes — UN-307 is compatible with all polyamide TFC, CPA, and ESPA membrane families (Dow FilmTec, Hydranautics, Toray, Suez). It is not chlorine-tolerant; dechlorination chemistry (SMBS, sodium bisulphite) must be dosed upstream of UN-307 injection.
How does UN-307 cost-in-use compare to Nalco PermaTreat 191 or Genesys LF?
On equivalent active-phosphonate basis, UN-307 lands at roughly 30–45% below Nalco / Genesys list price CIF Karachi. The Cost-in-Use calculator at /calculators/cost-in-use/ normalises against active-species per m³ treated; head-to-head autopsy data after 12 months on programme is available under NDA for refinery procurement.
Can UN-307 handle high-silica feedwater?
Yes — the polymeric dispersant component in UN-307 holds silica supersaturation at the concentrate side. Reference deployment: UN-307 at 4 ppm on a Mahmood Kot refining-sector RO train, feed LSI +2.3 with silica 42 mg/L; first-year silica fouling reduced 70% versus previous chemistry.
Where does antiscalant fit in the broader RO chemistry programme?
Antiscalant is one of two chemistries on a standard RO programme; the other is UN-611 RO membrane biocide for biofilm control. The complete refinery programme at /programs/refinery-process/ also covers feedwater audit, CIP planning, and membrane autopsy.
Read deeper into the programme.
Request a technical proposal for antiscalant for ro plant.
Send the unit you're trying to protect (site, loop or train, symptom or KPI, volume, deadline) plus a source-water analysis if you have one. Same-business-day Karachi reply with a programme outline, dose range, and the relevant CoAs / SDS attached.
Karachi office · Sole Pakistan agent · Shaanxi Ande & Innovative Water