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Aquus HVF-PHOS: Technical Data

Iron Zinc Aluminium Spray Dip
Aquus® HVF-PHOS 1.3 40-50 Liquid

A single pack, high performance, high coating weight product, benefiting from a robust operating temperature range. Coating weights are normally in the range 0.6 - 1.0g/m2
Download Technical Data Sheet as PDF

Aquus® ADDITIVE 530 A carefully designed surfactant blend, especially for more difficult cleaning applications. Operates at 40 - 60°C
Aquus® ADDITIVE 342 Additive for increasing the pH value of iron phosphate baths as well as neutralising iron phosphate baths for disposal purposes
Aquus® ADDITIVE 745 Additive for decreasing the pH value of iron phosphate baths, this is sometimes needed to combat carry over from preceding alkali cleaner stages.


HVF-PHOS is a heavyweight iron phosphate treatment designed for spray application on iron, steel, and zinc metals. It will clean the surface and leave an amorphous iron phosphate coating, which inhibits corrosion and improves the adhesion to post applied organic coatings.

Meets BS EN ISO 9717 2013 and DEF-STAN 03-11/5 Class IV.

HVF-PHOS: Concentrated base material
ADDITIVE 530: High temperature surfactant (Optional) for dip application
ADDITIVE 342: Acid consumed modifier
ADDITIVE 745: Acid consumed modifier

Testing Requirements:
Phenolphthalein indicator
BDH indicator 4.5
0.1M Sodium Hydroxide
0.1M Sulphuric Acid

Health & Safety:
This product is acidic. Click here to request a Health & Safety Data Sheet for safe handling and use.

It is recommended that the tank and fittings are made from stainless steel grade 316S16. This includes the heating elements and any spray nozzles. See a list of suitable equipment.

Process - Spray:
2. HVF-Phos (Second stage recommended)
3. Water rinse
4. Passivation (if required)
5. Drying

HVF-PHOS will degrease and phosphate in one operation. Pre-cleaning is not necessary unless the work is heavily soiled. If pre-cleaning is required, however, it must be followed by a suitable rinse stage.

Set-up and Testing:
The starting solution should be prepared by adding 13 litres (16kg) ofHVF-PHOS to every 1000 litres of clean water. Charge the tank with two thirds capacity of clean water, heat to 45°C and add the HVF-PHOS. Finally top up the tank with clean water and mix well.

Take a 10 ml sample of working solution, add 5 to 10 drops of phenolphthalein solution and titrate with 0.1N Sodium Hydroxide until the colour changes to permanent pink. Note the volume of 0.1N Sodium Hydroxide used. This is called the “pointage”.

A working solution prepared as above requires 4.5 ml of 0.1N Sodium Hydroxide and is known as a 4.5 point solution. To increase the “pointage” by one point add 2.9 litres (3.5 kg) ofHVF-PHOS per 1000 litres of working solution. Best results are achieved if the tank is tested and adjusted frequently.

Acid consumed:
After adjusting the “pointage” so that it is in the required range, take a 50 ml sample of the working solution and add 5-10 drops of BDH 4.5 indicator and titrate with 0.1N sulphuric acid. A colour change from blue* to reddish grey determines the end point of the titration. The number of mls of 0.1N sulphuric acid required is referred to as the Acid Consumed Pointage and this should be in the range 0.5 – 2.0.

To raise the Acid Consumed Pointage by one add 0.20 litres (260 gram) of ADDITIVE 342 per 1000 litres of working solution.

To lower the Acid Consumed Pointage by one add 0.16 litres (260 gram) of ADDITIVE 745 per 1000 litres of working solution.

*If the colour of the sample is reddish grey or red at this stage add caustic soda in increments of 80 gram per 1000 litres of working solution until the colour of the sample when taken from the tank is blue after adding the BDH 4.5 indicator.

Spray the work with the HVF-PHOS solution for sufficient time to convert the metal surface to a uniform coating. For best results a 2 stage process is recommended. The first stage takes 1 minute and the second stage takes 1.5-2 minutes. Alternatively a single stage of about 1.5 to 3.0 minutes should be satisfactory. If a pre-cleaning stage is undertaken, shorter process times of about 1 minute will be sufficient to generate a satisfactory coating. Coating weights are normally in the range 0.6 – 1.0g/m2.

Water Rinsing:
Following theHVF-PHOS treatment, the work must be rinsed with water. The flow of water through the rinse should be regulated to ensure that the rinse stage does not become excessively contaminated. Testing and control of rinse stages are covered in Technical Bulletin Number 1.

Following water rinsing, the work must dried immediately.

General Maintenance:
Automatic equipment can be used to monitor and control the strength of the HVF-PHOS working solution. Enviro Tech will, if requested, outline available equipment.

In the course of theHVF-PHOS process, sludge is formed as a by-product of the chemical reactions. This sludge settles to the bottom of the tank and should be removed regularly to prevent dusty coatings.

After the solution has been in use for some time, scale will form on the heating elements which must be removed at regular intervals to ensure that adequate heat transfer and proper processing temperatures can be maintained.

The timescale for maintenance depends on the use of the equipment and must be determined from experience.

HVF-PHOS solution must not be discharged to main drain without neutralisation and removal of any separated oils and solids material.

Further information

For more information or advice please contact us by telephone on +44(0)20 8281 6370 or email us using our contact form.
Thin Layer Pretreatment Processes are supplied and supported by EnviroTech Europe Ltd.

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