• ByRouging Solutions Editorial Team  ·  22 September 2026

CitriSurf 3050: Concentration, Temperature and Contact Time

Most people meet CitriSurf 3050 as a name on a quote sheet. The useful part is the numbers behind it, because those decide whether a cycle does its job or just gets the kit wet.

What Is CitriSurf 3050 For?

Low foaming work, mostly. Stellar Solutions sets it out in the CitriSurf 3050 product information sheet. The blend is "formulated for the cleaning and passivation of stainless steel products where very low foaming is required, i.e. CIP applications and baths with air agitation". That is the whole reason this grade exists in the range.

Foam is a real problem in a recirculating loop. It traps air against the metal, starves patches of the surface and makes the level hard to read. A product that foams less is easier to run for an hour at temperature.

That matters more in a plant than it sounds. A foaming bath trips level sensors, and an operator who cannot see the liquid line starts guessing. Guessing is how a cycle ends up running at the wrong strength.

The maker is clear about the metal too. It is designed for "austenitic and duplex grades of stainless steel", which covers the 304 and 316L found in most pharma and dairy plants.

One fix is worth making early, because the error is common. CitriSurf 3050 is a liquid. The manufacturer's own data sheet lists the form as Liquid, with a specific gravity of 1.25 and a viscosity of 6 cps. If you need a gel for vertical surfaces or spot work, that is a different product in the CitriSurf range.

What Concentration Does CitriSurf 3050 Need?

Between 7 and 13 percent by volume in water. The data sheet gives the normal working concentration as "7-13% by volume in water". The mixing instruction reads "1 part of CitriSurf 3050 with 7 to 14 parts of water by volume". For a clean in place loop it adds that "A ratio of 1 to 10 is typical for CIP".

That range is wider than it looks at first. A 1 to 7 mix is nearly twice the strength of a 1 to 14 mix. So "CitriSurf" on a batch record means very little on its own. Write the ratio down next to the product name.

Mix in clean equipment. The sheet asks that "All equipment, mixers, tanks and pumps should be clean and dry prior to mixing". It names polypropylene or stainless steel for the tanks and pumps.

Water quality is worth a thought here too. The sheet allows clean water and says purified water may be used if you want it. On a site with hard bore water, purified water for the final rinse is usually the better place to spend the money.

How Hot Should the Solution Run?

Warm, and warmer than most Indian plants run it. The listed operating temperature is "Room temp or higher (120-160F preferred)", which is roughly 49 to 71 degrees Celsius. The sheet is blunt about why: "Heat the solution for optimum performance."

Heat also fixes foam. The notes say "Increased foaming maybe observed at cooler temperatures" and tell you to heat the solution to reduce it. So a plant running cold to save on steam often ends up fighting foam it created.

If you do heat, watch what you heat with. The sheet recommends "Teflon coated (or equivalent), stainless steel or titanium heating devices", which rules out a lot of improvised immersion heaters.

A mild steel heater in a citric bath is its own source of free iron. You would be adding the contamination the cycle exists to remove, and the ferroxyl test at the end will find it.

How Long Should a Cycle Run?

Long enough to strip the free iron off the surface, and the right figure depends on what you are treating and how dirty it is. The data sheet gives two figures. "CIP operations are typically run for 30-60 minutes." For loose parts the time "is typically 5-20 minutes", and the sheet then lists what changes it.

The word typically is doing a lot of work there. The sheet lists what moves the number: "temperature, grade of stainless steel, hardness, use of ultrasonics, and the condition of the surface of the parts". A scaled surface takes longer than a clean one.

That is also why the sheet says "Your tests should indicate the best combination of bath parameters for the products you manufacture". The numbers are a starting point for a validation run. They are not a recipe to lift into an SOP untested.

Rinse immediately after. The instruction is to rinse "thoroughly with clean water", with flowing water called optimum, then "Dry completely in air immediately". A part left wet is a part you may have to do again.

Drying is part of the process, and the sheet says so. It notes that a hot air oven or another drying medium speeds it up and helps you "attain a highly passive surface". Air drying in a humid Mumbai monsoon is slower than the same job in March.

Which Grades and Standards CitriSurf 3050 Covers

The metal first. It is built for austenitic and duplex stainless, so the 304 and 316L in a WFI loop or a dairy line are squarely in scope. High carbon, sulfur or selenium grades need a pre-clean first. The sheet points to "a good water based alkaline cleaner" before the acid step.

On standards, quote the qualifier. The sheet says that "When used correctly, CitriSurf 3050 meets the requirements of the ASTM A967, ASTM A380, ASTM B600, and AMS 2700 standards". Those three words carry the whole claim.

Nobody is certified to A380 in any case. It is a practice, and a specification is the kind of document that sets a pass mark. Our guide to what ASTM A380 covers explains that split. ASTM A967 is the one that sets the pass mark your test has to clear, and its published scope says so.

There is one more line worth reading twice. The sheet asks that you test your own products with CitriSurf before production use, because "Every product and production facility is different". Treat the numbers here as the start of a validation, and let your own results set the final recipe.

What Goes Wrong on an Indian Line?

Four things go wrong more than anything else, and none of them is the chemical itself. The first is a ratio nobody wrote down. The batch record says CitriSurf and nothing else, so nobody can tell whether the cycle ran at 7 percent or 13.

The second is temperature drift. A jacketed tank that holds 140F at the start and 95F by minute forty has quietly changed the process. The record often shows one reading, taken at the start.

The third is rinse water. Good chemistry followed by hard bore water leaves spots. Those spots get mistaken for rouge at the next inspection. Our note on identifying rouge covers telling the two apart.

The fourth is skipping the pre-clean on greasy equipment. The sheet is explicit that heavy grease and oils should come off first. Otherwise the acid spends itself on the soil and never reaches the free iron.

How Do You Keep the Bath Working?

Watch the pH, and top the bath up before it drifts. The sheet sets a tight control band. The pH "should be held to within +0.1 of its initial value for normal operation", starting from roughly 1.8 at working strength.

Topping up is part of normal running. The maker tells you to "Replenish the bath with CitriSurf and water as appropriate to compensate for dragout, evaporation, and acid consumption". Dragout alone will pull a bath off strength over a shift.

Storage matters between runs. Keep the drum "between 50F and 120F", which is about 10 to 49C, in 316 stainless or approved polyethylene or polypropylene. A drum left on a Vapi rooftop in May is outside that band before lunchtime.

Our passivation team runs these baths on client sites. We log the ratio, the temperature and the pH on every cycle, because those are the readings an auditor asks for.

Where to Start

Pull your current SOP this week and look for three numbers in it: the mixing ratio, the target temperature and the contact time. If any one of them is missing, that is this week's job. Most SOPs we open name the product and stop there.

Then check what your batch record actually captures. A single temperature reading at the start of a forty minute cycle tells you very little, and two readings cost nothing.

Run a test batch before you change anything in production. The maker asks for it in writing, and it is the cheapest way to find out what your own surfaces need. Rouging Solutions can run that first batch with you.

Frequently Asked Questions