CERTIFICATE OF ANALYSIS
product : CENO FLUX-NHL P251

Results of the tests
Solution temperature : 76^oC

pH-value : 5
Viscosity : 7.26 sec
Separation volume I : 99ml
Separation volume II : 71ml
Grain
        >315 : 2.70%
        >200 : 7.60%
        >100 : 29.12%
        >40    : 42.27%
        <40    : 18.30%

Lithium chloride                       7447 - 41 - 8
Stromium chloride                   10476 - 85 - 4
Sodium fluoaluminate               15096 - 52 - 3
Potassium fluoride                   7789 - 23 - 3
Zinc chloride                           7646 - 85 - 7

CENO FLUX - NHL P251

(Al Brazing Flux)

Technical data:

Active temperature:                 520 - 640^oC

Melting range:                         510 - 560^oC

Conditions as received:             white powder

Solubility in warer at 20^oC:       abt 150g/l

pH value (10g/l) at 20^oC:           abt 6.5

Product Information

Al brazing Flux (CENO FLUX NHL P251)

Brazing fluxes Type SEKI are fluxes Type F - Li, with an active temperature of

520^oC - 640^oC This kind of fluxes is based on hygroscopical chlorides and fluorides.

CENO FLUX - NHL P251 is suitable for brazing processes at aluminium and aluminium

alloys with Mg-content up to abt, 2.5% in weight. As brazing solder there can be used

aluminium - silicon (AlSi) alloys with 7-13% in weight of silicon.

With regard to SEKI BRAZING process with our CENO FLUX - NHL P251 We are

introducing you step by step as follows:

Preparation of initial bath suspension:

Flame brazing:

1. 25% in weight of water(preferably distilled water) as a basis

2. 75% in weight of CENO FLUX NHL P251 by degrees stirred with the water lumpy-free.

Furnace brazing:

Steps 1. and 2. as above described.

3. Initial bath suspension stir for 5 hours and with water mix to a viscosity resp.

   draining time of approx. 7.5sec. (DIN-viscosity cup with 5 min nozzle).

After adding of water stir properly again till required viscosity is obtained.

Attn. : The final adjustment of viscosity should take place according to specific factors

       for use.

Attn. : During Preparation of hydrous suspensions there takes place an exotherm

       reaction which may heat up the preparation to nearly 100^oC.

Pre-cleaning

Pre-cleaning is necessary to remove existing oil - and grease residues caused by hot

rolling and pressing from the surfaces to the parts because those may possibly prevent

a wetting with flux and this way make impossible flow of the brazing solder.

Corroding and degreasing takes place in media, such as alkali solvents (e.g.NaOH)

acid solvents (e.g.HNO₃) or 1.1.1.trichlorethan resp. perchlorachylen.

Brazing process:

Brazing process takes place in open - furnace atmosphere in ambient-air furnaces

or in fore of flame - brazing.

The choice of temperature is dependent on the plating base material.

Post cleaning:

1. Splash still warm radiators resp. heat exchangers (that is with object temperature of

   300-400^oC) after brazing process with cold water (quenching). This way the flux slag

   caused by different extensions of heat of Al-material gets loose (consequently physically)

   and bursts into little single particles.

2. After pre treatment accord. to 1. lift the radiators resp. heat exchangers up single or more.

   frequent put them into baskets, if possible in sloping position and then rinse sufficiently

   by frequent dipping into warm water (min, 60^oC - max. 90^oC). With Al-oil-coolers take care

   of rinsing sufficiently both the oil-and air resp, water face.

3. After this drain off the radiators resp. heat exchangers or possibly(if necessary) blow

   through with compressed air and once more treat with normal tap water as described above.

4. Following 1-3 the radiators resp. heat exchangers have to be dipped resp, flowed in nitric

   acid (approx, 5-10% HNO³ remainder water) with about 50-60^oC bath temperature

   (dipping as described above).

5. Hereafter we recommend dipping and flowing of radiators resp. heat exchangers in cold

   normal tap water again.

6. The remaining water adhering to the radiators resp. heat exchangers should get evaporated

   in a suitable drying stove with a temperature if possible more than 130^oC.

It stands to reason that described sequence of proceeding is variable, however measures and

construction details have to be considered in any case, even special surface eflicts may be

obtained by mixing to the nitric acid a small quantity of hydrofluoric acid (HF)

(approx. 0.5 - 1.0% in weight).