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Update
The NOCOLOK dictionary was the reference book for the brazing of aluminium at its release over a decade ago. Now it has been completely revised and published under the name NOCOLOK Encyclopedia, with many additional chapters including a chapter on special fluxes. Within the new, fresh and tidier design lies concentrated knowledge for technicians and users in the aluminium industry. Many illustrations help make complex processes more understandable.
The PDF file is fully linked and keywords are quickly found using the built-in Acrobat Reader search function. The encyclopedia is free of charge and available for download.
Connected Global Thinking and Local Support
Arnaldo Huitron has worked for Solvay Flúor México as Sales & Marketing Manager in the GBU Solvay Special Chemicals for more than 14 years. He is responsible for all fluorinated products, including NOCOLOK.
Arnaldo is a chemical engineer and MBA with a great deal of experience in marketing and enterprise management. Before he joined Solvay he was employed at ICI Mexicana and Q. Hoescht México for several years.
Arnaldo offers commercial and technical support for NOCOLOK to customers in Mexico and Nafta. Solvay Flúor México distributes NOCOLOK throughout the country over four different warehouses with the aim to satisfy the demanding and growing heat exchanger industry in México. Solvay organized technical visits and seminars along with our Nafta technical team, tailoring them to each particular case of the heat exchanger industry, also supporting all the projects through the R&D centre in Hanover, Germany.
The seminars are given in both Spanish and English for a better assimilation from the technical staff of each individual company.
Update
The update of the NOCOLOK App 2.0 for iOS and Android has been available for some days now. Most users have already automatically received an update for their Smartphone. What does the new version offer?
- All NOCOLOK products are classified according to GHS guidelines
- The packaging chapter has been completely revised and updated
- Two additional calculators for increasing or decreasing the slurry concentration are available
- The NOCOLOK encyclopedia has been completely updated parallel to the PDF version
- The iOS version 6.0 is completely supported
And for those who do not yet have the NOCOLOK app on their Smartphone: now is the best time to download! Here are the links to the Apple AppStore and to Google play.
The app for Blackberrry will come soon.
Invitation
EABS and Solvay Fluor GmbH announce the twelfth annual presentation of their joint technical training seminar entitled:
Dates: 24th and 25th September 2013
Please download your Seminar Registration Form here
Purpose of the Seminar:
This technical training seminar will be presented in the English language at the Conference Centre and laboratories of SOLVAY GmbH, in Hannover, Germany. It will provide information concerning the manufacturing practices commonly used for brazing operations and, in particular, will address the three fundamental aspects of the industrial-scale brazing of aluminium.
These are:
- The flame brazing of aluminium.
- The Controlled Atmosphere Brazing (CAB) of aluminium heat exchangers with non-corrosive fluxes (NOCOLOK® Flux).
- The methodology of how to ensure that the brazing process selected is, indeed, the one that represents ‘best practice’.
Who should attend this two-day seminar?
- Technical staff who need to have a specific understanding of either one or both of the fine details of the technology of the brazing of aluminium with flames, and/or the NOCOLOK® furnace brazing process.
- Design and production engineers who are fabricating, or who are intending to fabricate, aluminium pipe-work assemblies and/or condensers and/or evaporators.
- Production Engineering Department Managers whose duties include day-to-day responsibility for the brazing of aluminium.
Follow this link to see what you can expect when you attend this seminar
EABS Technical Training Seminar: Aluminium Brazing and NOCOLOK
Here you can find the detailed seminar programme.
Review
Solvay Special Chemicals is the global leader for aluminium brazing flux. Almost every vehicle is equipped with a heat exchanger made of aluminium and most are brazed with NOCOLOK. The NOCOLOK team had the privilege of attending a Tech day at a major automobile manufacturer in South Korea.
Five Solvay Global Business Units, including Engineering Plastics, Specialty Polymers, Rare Earth Systems, Special Chemicals, and Aroma Performance, took part, showcasing innovations in four areas of chief importance for the automotive industry: light-weighting, electrification, green & clean technologies, and power train efficiency. These topics were covered through a series of poster sessions and oral presentations.
Daejun Han, Sales & Marketing Manager Asia Pacific, presented the possibilities of aluminium brazing with NOCOLOK with technical posters, videos, and the experimental glass-brazing furnace. "The automotive engineers were particularly interested in the NOCOLOK specialties Sil Flux and Zn Flux and the improved corrosion resistance," Han said at the end of the event, which was attended by over 900 participants of the automobile manufacturers.
Review
The China Refrigeration has established itself as one of the biggest exhibitions for the HVAC&R industry. More than 50,000 people attended the three-day event in Shanghai in early April. Under the motto “Serving People’s Well-being, Promoting Ecological Progress” 1,146 exhibitors from 30 countries presented themselves on 93,000 m2.
Of course the NOCOLOK Team was present, not least because the Asian market, with its high growth potential, is one of the main customers for NOCOLOK flux, especially in the heat exchangers for air conditioning sector.
The balance after three days was very positive: “We are surprised at the level of awareness of the NOCOLOK brand, especially in China and from the many new contacts,” reports Toby Ding, Asia Pacific NOCOLOK Technical Service Manager.
NOCOLOK Survey 2013
Would you like to win an iPad Mini? Then grant us five minutes of your time to give us your opinion and, with a little luck, you could win an iPad Mini with 16GB storage and Wi-Fi connection. Just click on the link and answer the questions in our Customer Satisfaction Survey. In early July we will raffle a white iPad Mini among all fully completed questionnaires from the period March 1 to June 20. And, you have a second chance to win early next year: among all 2013 participants we will be raffling a PlayStation 4. Participants from 2012 are welcome to cast your vote again, offer your evaluation and win one of five prizes we are giving away in 2013.
We look forward to hearing your opinion!
Click here for the survey
Technical Statement
Since the early 1980’s, controlled atmosphere brazing (CAB) using non-corrosive fluxes has evolved as the dominant process for manufacturing aluminium heat exchangers. Since its introduction, Potassium Aluminium Fluoride brazing flux (NOCOLOK Flux) has been used without any change to the chemical composition in brazing operations (i.e. CAB/furnace, flame, and induction).
Significant changes that have occurred over this period of time include:
- Coolant chemistry - basic types: Inorganic Additive Technology (IAT), Organic Additive Technology (OAT), Hybrid Organic Additive Technology (HOAT), plus additives, plus pH buffers
- Design of heat exchangers incorporating more internal brazed surfaces with increased internal fluxing (e.g. on folded tubes, inserts, turbulators)
- More heat exchangers in the system loop - and thus additional brazed surface area in contact with coolant
- Reduced coolant volumes as a result of smaller and more efficient designs
- Coolant system materials of construction (new alloys, engineered polymers, mold release agents)
- Increased fluid flow velocities through HEX components (erosion)
- Increased local engine temperatures due to bigger specific power (manifolds, cylinder head, water cooled turbochargers, cylinder liner)
- Introduction of low temperature radiator without degassing systems
Over the last several years, discussion of flux residue remaining on internal surfaces of brazed aluminium heat exchangers has become an industry hot topic due to engine coolant stability issues that historically had not occurred prior to the coolant system changes noted above.
As a leading flux manufacturer, Solvay has been working with our customers and other industry suppliers to better understand the part that post brazed flux plays in this discussion.
Key observations:
- Post braze flux residues on internal wetted surfaces of brazed aluminium heat exchangers are slightly soluble in currently used commercial coolants. Parameters affecting the level of dissolved flux in coolants include:
- Flux residue quantity
- Time of exposure to the coolant
- Temperature
- Coolant formulation and additives
- pH stability of the coolant
- Water content of the coolant
- Number of brazed heat exchangers in the loop (total brazed internal surface area)
- Experimental data indicates that some coolant additives react with dissolved flux, in particular with the aluminium component of flux.
- The coolant additives are designed to interact with aluminium species.
- It is important to note that aluminium oxides may be present from normal detachment within aluminium heat exchangers, unassociated with flux residue. As an example, coolants used in vacuum brazed heat exchangers show presence of dissolved aluminium in the system from this effect.
- Slight flux dissolution occurs in water and coolants at neutral pH - but increases at acidic and alkaline pH levels. Many coolant formulations operate at alkaline pH, which increases the solubility of flux residue and of aluminium oxide.
- Certain coolant additives can affect flux residue solubility. For example the addition of borax (Na2[B4O5(OH)4]·8H2O) increases flux residue solubility, while the addition of a phosphate (KH2PO3) slightly decreases the solubility of potassium aluminium fluorides.
A recent result of our research is that Solvay determined a no impact threshold limit of dissolved flux derived from joint work done with coolant, heat exchanger, and automotive manufacturers: In this specific case for a silicate-based coolant, a threshold limit of a maximum of 0.5 grams of dissolved flux per liter of coolant (50:50 mix ratio with water) could occur with no noticeable depletion of the silicate reserve. Such threshold limits must be determined for each coolant formulation individually - considering also the exact coolant/water mixing ratios.
As part of this study it is important to note that we found no evidence that fluorides cause depletion of silicates.
Determining dissolved flux levels in Coolants
Several OEM automotive and truck producers are introducing specifications for internal heat exchanger cleanliness. In many cases potassium concentration measurements are used to verify how much flux residue dissolves in the coolant or water volume of a brazed heat exchanger. It must be emphasized that more flux residue dissolves in water than in coolant/water mixtures.
Based on the threshold level mentioned above (0.5 g/l) the corresponding potassium concentration would be 150 mg/l. Note that some coolants contain potassium species in the original coolant composition and this must be taken into account when evaluating the results.
Due to the chemical interactions of fluoride with aluminium oxide and dissolved aluminium we do not recommend using fluoride concentration measurements as an indicator for dissolved flux residue. Furthermore, when using fluoride sensitive electrodes for analysis, it is challenging to distinguish between free fluoride ions and complex fluoride ions (e.g. AlF4–); thus, the results could be misleading.
Analyzing the exact level of aluminium in solution from dissolved flux residue is also problematic. Aluminium ions at alkaline pH will form aluminium hydroxide, which has low solubility and partially precipitates. This generally leads to Al concentrations lower than those calculated on the basis of the potassium values.
Other factors
OEM’s, coolant manufacturers, and heat exchanger manufacturers have determined that other important factors besides flux residues play a part in coolant system stability. A partial list follows:
- The nature of the coolant composition and coolant additives
- Coolant system operating design that avoids overheating and hot-spots
- Minimization of coolant exposure to air
- Avoiding exposure of coolants to exhaust gases
- Usage of inert coolant system materials of construction
- Prevention of oxidized iron/steel components prior to coolant fill
Summary
Coolant stability is critical to ensure proper engine heat management and to achieve the expected lifetime of modern heat exchanger systems. The heat exchanger design, operating parameters, materials of construction, and coolants all must be evaluated as they each impact system stability.
It has been shown that interactions can occur between the dissolved flux component and certain coolant additives. Understanding which additives may interact with dissolved flux is important. Of course, to reduce the amount of dissolved flux, the minimization of flux load becomes an important goal in the heat exchanger manufacturing process.
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