Electrolux 267712 (AOS101GTD1) Datasheet

Brand: Electrolux

Model: 267712 (AOS101GTD1)

Type: Datasheet

Electrolux 267712 (AOS101GTD1) is a single oven that combines microwave and traditional oven cooking modes, allowing you to cook a wide variety of foods quickly and easily. The microwave function is perfect for reheating leftovers, defrosting frozen foods, or cooking quick meals. The traditional oven cooking modes include bake, broil, and convection, giving you the flexibility to cook everything from roasted chicken to pizzas to cakes. The oven also features a self-cleaning function, making cleanup a breeze.

Here are some of the key features and benefits of the Electrolux 267712 (AOS101GTD1):

Technical Bulletin

Identification:

Bulletin no:

Date:

Issuer:

Factory:

GENERAL

PDX2000-09

19-09-2000

R.ZAGO (T.T.&S.)

Vallenoncello Cooking

POSTAL ADDRESS TELEPHONE TELEFAX

ELECTROLUX FSE Electrolux ZGI V.le Treviso 15 +39 0434 380570 +39 0434 380555

33170 PORDENONE - ITALIA

Page 1

FOOD SERVICE EQUIPMENT

English language

THE WATER AND THE APPLIANCES FOR

PROFESSIONAL COOKING

THE WATER AND THE APPLIANCES FOR PROFESSIONAL

COOKING

WHAT YOU NEED TO KNOW BEFORE SELLING AND INSTALLING AN APPLIANCE

Object

The lack of information, and the fact that there is not such a thing as a “culture of the water” among

those professionals who operate in the catering sector, is most times the source of many technical

problems which then cause the fast degradation of performance and reliability of the appliances used

for cooking foodstuff. The object of this technical bulletin is that of supplying our retailers and

engineers who carry out the installation and servicing of machines and appliances with the necessary

and sufficient elements that will allow them to evaluate first and to operate then so to avoid any

damages the water might provoke (corrosion and scaling) on the materials used for manufacturing the

machines and to choose the best water treatment possible.

Application field

Combined ovens with and without steam generators, indirect pans and all other functions of usual

modular catering .

The water, general news …

The water in the world is ever the same, it gets continually recycled in a perfect closed system. The

water in the seas, rivers and lakes evaporates continuously provoking the separation of impurities and

salt which remain in solid state.

Therefore water ascend towards the higher stratus of the atmosphere where it condenses to the solid

state dissolving (loading) the oxygen and the nitrogen and then precipitates on the earth (rain, snow,

hail) dissolving the carbon dioxide that the water contains. When the water enters in contact with the

soil and while flowing through the superficial stratum, the salt contained in the water dissolves. Then

water flows along impervious underground stratum until it gets pumped outside or it finds a natural

outlet. Now it continues flowing, it loads bacteria, it fills with vegetal and animal life until it evaporates

again so starting its natural cycle.

a) The water may contain substances such as:

b) Big suspended particles (sand, organic substances)

c) Average colloids (sulphides, metallic hydratez, detergents)

d) Molecular solutes such as gas, undissociated (sugar and silicates) and dissociated (ions)

molecules.

The main gas dissolved in water are… … Nitrogen (N2), Oxygen (02), Carbon dioxide (CO2),

Ammonia (NH3), Natural gas (CH4), Chlorine (CL2).

And the ions dissolved in water are …. Hydrogen (H+), Potassium (K+), Calcium (Ca++), Magnesium

(Mg++), Iron (Fe++), Copper (Cu++), Chloride (Cl-), Bicarbonate (HCO3-), Carbonate (CO3--),

Sulphate (SO4--), Phosphate (PO4--)

Apart from these elements the water contains also living organisms such as mildew, weeds, bacteria,

virus and chemical compounds deriving from industrial technological treatments.

Water is considered drinkable when suitable for human diet. To be drinkable water must contain every

element within a maximum limit of concentration.

Other substances must be absolutely absent such as: bacteria, virus, mildew, weeds, fungus, lead,

arsenic, chromium, cadmium, barium, cyanide, selenium.

Drinkable water might not be suitable for the correct functioning of a cooking appliance.

What is the corrosion…

Corrosion is the electrochemical phenomenon that provokes the progressive deterioration of all metallic

materials that enter in contact with aggressive agents (water, humidity). All professional cooking

machines are made of stainless steel (Aisi 304, 430); these materials are more resistant to corrosion

than other ones thanks to the greater presence of chromium (10,5 that distinguish stainless steel from

other iron alloys. This element is capable or reacting (passivation) when entering in contact with air

containing great quantities of oxygen (oxidant agent) by forming a special oxidized superficial film that

protects the material underneath. When stainless steel is in these conditions it is called “passive” and it

means that the metal is subjected to a very slow thermodynamic corrosion. Otherwise stainless steel is

called “active” when it reacts rapidly to the corrosion process. Naturally the passive film will get

recreated when ripped if the environment is sufficiently oxidant and if the oxygen is able to enter in

contact with the alloy. In short, it means that these materials protect themselves against the corrosion

by means of an “auto-regenerative protective skin” that slows down the electrochemical corrosion

process. According to the state it is in, passive or active, the stainless steel will oppose a valid

resistance to corrosion or will be destroyed by it. Even if the stainless steel resistance to corrosion is

greater that that of other metal it does not mean that, depending on its atomic structure, on special

environmental conditions, on the type of technological process undergone and mainly to the presence

of particular aggressive agents, after a variable incubation period the material protective film might get

ripped. In these conditions the destruction of the material underneath is very fast arriving to break or

even to get perforated. Hence there are not such a thing as a “magical” material but only materials that

can be more or less resistant to corrosion. There are various forms of corrosion, the following ones are

those more common for cooking appliances:

UNIFORM CORROSION

It is most common for fry-top and iron brat-pans. Corrosion forms a oxide film on a wide surface when

in presence of a very aggressive environment (humidity, water), it attacks mainly iron and specially

rough surfaces.

STRESS CORROSION Fig. A

Fig. A

It is very common on cooking appliances and it shows on

cells, steam generators and oven heat exchangers and in the

indirect pans cavity walls. It appears when the material present

in the corrosive environment gets mechanically stressed by

traction or cut in static or dynamic conditions. It takes the

form of branched cracks near the welding at a very high

penetration speed (up to 2 mm/hour) so that when the crack

becomes visible the material is already damaged. Stress

corrosion happens mainly caused for the following connected

facts:

• Stress by external traction due to the use of the appliance

itself or caused by the presence of material internal pressures

due to cool mechanical process (plastic deformation such as

stuffing and bending) or to thermal treatment (welding).

• Presence of an corrosive environment ( Chloride )

• Frequent thermal variations and high temperature.

Stress corrosion is a electrochemical corrosion but accelerated by the mechanical stress.

Intercrystalline corrosion Fig. B

Fig. B

It etches chromium stainless steel (Aisi

430-304-316-321), the material crumbles

and gets pulverized grain by grain. The

crystal lattice that unites the molecular

structure of stainless steel brakes due to

the precipitation of the chromium carbide

on the borders of grains at temperature

higher than 500°C. Imagine 2 contiguous

crystals, part of the chromium migrates

towards the border between two grain so

incrasing the concentration of chromium

on the border of every grain which

becomes much higher than the material

average. This way the concentration on

zones (fig. B1) near by the grains borders

gets depleted of chromium until

“uncovering” the zones right by the

borders that this way become vulnerable to

corrosion agents. So both grains separate. The weaker parts are the ones that have undergone thermal

treatments (welding) and mechanical processes (moulding, bending, skirting, etc…) and that operate at

temperatures between 450 and 850° such as heat exchangers).

PITTING - Fig. C

Fig. C

This is the most common one on the

cooking appliances, very much on the

pans wells and brat-pans and easily

recognizable once the process is in

course due to the formation of black

points (from 0.1 to 1 mm) that can

even perforate the whole material

thickness. It shows when the stainless

steel is left in contact with the

contaminant solution (salt or water

having a very high percentage of

chloride) locally and in stagnant way.

The point shaped corrosive attack

operates in two phases, the first one

called “incubation phase” brakes the

passive layer, the second one called

“growing phase” presents a penetrating

or cavernous self-accelerating process

in the sense that feeds itself. From the

electrochemical point of view the

phenomena is caused by the formation

of a kind of battery between the metal

(cathode) and the contaminant (anode);

the electric current between the

cathode and the anode brings in the

solution (dilutes) the metallic ions so

creating the pitting. Chlorine ions CL-

increase on the bottom of the pitting so

speeding the point penetration while

the lack of oxygen on the pitting

bottom prevents any attempt to

regenerate the passive film.

GENERAL RULES

Before carrying out any operation on the product or on the installation it is convenient to define

precisely some fundamental concepts that apply to all machines used for cooking foodstuff. Lets listed

here bellow:

• As already described the corrosion is a complex phenomenon that shows itself in various forms

and different causes that provoke the same effect, that is to say the destruction/breaking of the

material. The main cause of any type of corrosion is THE CONCENTRATION OF

CHLORIDE in the water. The greater the concentration of chloride the more aggressive will

become water and consequently the fastest will be the corrosion phenomenon.

• Once the stress or intercrystaline corrosion processes are in course (since the moment it is visible

to the naked eye), the phenomenon can not be stopped but only slowed down. Therefore

prevention it is most important by measuring the quality of water and installing the most suitable

water treating system while installing the appliance. As we intend to demonstrate along, pitting can

be removed if diagnosed in time.

• Temperature helps the corrosion process acceleration; having the same concentration of chloride

and material, corrosion process will be faster on that material which operates at the highest

temperature.

How to prevent corrosion… and scaling …

The measuring phase …

Water is, therefore, the most dangerous element since it might contain contaminants; remember that

drinkable water could be harmful to the appliances and so it does not represent any “security”.

Before installing an appliance you need to control that the tap water is suitable to be used by means of

the 3 parameters that influence aggressiveness against corrosion such as :

1. Concentration of chloride

2. Electrical conductivity

3. PH

A forth parameter is fundamental for the appliances to work correctly: the water total hardness; this

value determines the capacity of a particular type of water to produce scaling.

As already said, the quantity of chloride in solution is the most important characteristic that determines

the initiation and propagation of the corrosive phenomenon. It gets measured in mg/l (milligramilitre)

or ppm (parts per million) by means of a kit (fig. 1-2) which is very easy to find.

Fig. 1 Fig. 2

To measure the quantity of chloride in the water carry out the following operations:

1. Take 6 ml of water using the special syringe and inject it in the 2 containers (fig 3)

2. Dissolve 6 drops of reactant Cl-1A in both containers (fig.4)

3. Close one of the containers and place it on the left part of the comparator (fig.5)

4. Dissolve 6 drops of reactant Cl-2A in the other container, close it and shake it, then place it on the

other hole of the comparator (fig.6).

5. Compare the right sample colour with the supplied chromatic scale, when colours are the same

read the ppm value on the bottom right side (fig.8).

Fig. 3 Fig. 4 Fig. 5

Fig. 6 Fig. 7 Fig. 8

The conductivity is the propriety that allows the water to conduct electric power, it gets measured in

microsiemens/cm by means of a conductivitymeter (Fig.9).

Switch on the instrument and plunge it in the water, then read the value displayed by the relative

indicator (fig.10-11).

Fig. 9 Fig. 10 Fig. 11

The PH indicates the acidity or the basicity of water from 1 to 14 in which 7 represent the neutral,

under this value you have a acid solution, over this value you have a basic solution. The more acid the

water the more aggressive. The PH is easy to measure by means of indicative paper strips (fig.11)

which colour change when immerse in the solution you need to measure. Then you compare the colour

of the strip with an special chromatic scale supplied to find out a good approximate value.

Fig. 12 Fig. 13 Fig. 14

The total hardness express the capacity the water has to form magnesium and calcium carbonate

(CaCO3) more commonly called scaling, scaling is favoured by the increasing of temperature.

These compounds deposit on the container walls and piping forming the scaling which often breaks the

cooking machine. The total hardness is measured in French degrees or milligramlitre of calcium

carbonate with the following relation: 1°F = 10 mg/l

Sometimes the water hardness is also measured in German degrees (°d) with the following conversion

1°F=0,56 °d. Water is called “soft” when hardness value varies from 0 to 10 °F, low hard water when

hardness varies between 11-20°F and very hard > 40°F.

The hardness values advisable for installing cooking machines are those compressed between 0,5 e 5°F

To measure the hardness there is a kit (fig.15) easily find in the shops that has to be used as follows:

1. Take 5 ml of tap water using the syringe and fill it in a test tube (fig.16)

2. Dilute 3 drops of reactant 1 in the test tube and shake it (fig.17), the water becomes red coloured

(fig. 18).

3. Using the special pipette take reactant 2 until filling up the pipette to mark “0” and dilute the

contains of the pipette one drop at the time until water in the test tube becomes green (fig. 19-20-

21)

4. Read the hardness value on the graduated scale; in case you need to add again reactant 2, add the

values read during the second measuring on the graduated scale (fig. 22).

Fig. 15 Fig. 16 Fig. 17

Fig. 18 Fig. 19 Fig. 20

Fig. 21 Fig. 22

The choice of the water treating system …

Once you have measures the 3 parameters related to corrosion and the total hardness regarding the

scaling, control if the tap water needs to be treated and if so try and choose the most suitable system.

First of all control the water aggressiveness and then the water hardness, you will choose the system to

be installed by combining the 12 following results:

1. Choose the reference table according to the appliance you intend to install (C for FCV with steam

generator; B for ISG ; A for indirect pans ) .

NOTE: THE TABLES HERE BELLOW ARE TO BE USED AS A REFERENCE FOR AISI 304

APPLIANCES.

2. Multiply the conductivity value for the PH value read and mark the value on the axis of the

abscissa (fig.16).

3. Mark the chloride value read on the ordinate axis (fig.17).

4. Cross unite the 2 resultant values and check in area you are, for example in case of having as

reference table C:

Area 1 = No treatment required

Area 2 = Install a NANOFILTER

Area 3 = Install an OSMOSIS

Example : You have measured the tap water and read these values PH=6.4 ; Conductivity = 850mS/cm;

Chloride = 35 ppm and you need to install and oven and steam generator (as a reference you need to

use table C) the suggested treatment is that of installing a NANOFILTER .

Now according to the value of the total hardness measurement, you need to combine both results to

choose the most suitable treatment using as a reference table D .

Tab. D

Not required Not required Nanofilter Nanofilter Osmosis Osmosis

< 5°F > 5°F < 5°F >5°F < 5°F > 5°F

Not required Softener Nanofilter Nanofilter Osmosis Osmosis

Where …

1= Measuring result of tables A,B,C

2= Total hardness measuring result

3= Treating system to be installed

As you can see, both the nanofiltering and inverse osmosis resolve the problem, so it is convenient to

install a water softener, which is more convenient, only when you have not very aggressive hard water.

While installing one or more appliances pay attention also to these points:

• Make sure there is a 100 micron cross section net filter installed to eliminate suspended solid parts

(sand, metallic residuals, etc…) that could tamper the valves and cocks and are the source of many

bacterial infections. Clean the filter every 2 months more or less.

• Control the water static pressure on the appliance inlet using a pressure gauge; pressure value

must be compressed between 1,5 and 3 bar .

• If you need to install a water softener, control that there is also a sterilization system to prevent

bacterial proliferation.

• If you need to install steam generator ovens and an inverse osmosis device, water conductivity

falls almost to zero. Under these conditions the water level control system of steam generator will

not work, and therefore you will need to reset a certain minimum salinity level in the water. To do

so by-pass a certain quantity of not-treated water to obtain a conductivity in the steam generator

inlet of at least 50 microsiemens/cm.

Tab. A

Tab. B

Tab. C

THE ADVISED TREATING SYSTEMS

NANOFILTERS type ZA01 – code 922186

The nanofiltering treatment operates making water in pressure pass through a filtering membrane

which holds suspended substances (salt). The nanofilter reduces the quantity of chloride of 80% (if you

have 35ppm in the inlet, there will remain 7 in the outlet) and “purifies” around the 80% of all

substances contained; on the average you will have 30 litres of “purified” water every 100 litres.

Correct maintenance of prefilter and membrane is most important for the machines best performance

and therefore for the appliance itself. Replace the prefilter twice a year, wash the membrane twice a

year and replace it every two years when water has a hardness value up to 40°F, when hardness

value is superior to this value the filter should replaced at least 3 times a year, for replacing instructions

consult the installation and use instructions manual.

The inverse osmosis treatment is similar to the prefiltering one but for the fact that the reduction of

salinity and salt chloride in the water falls to 99%. The inverse osmosis system is a good prevention

against corrosion but for the cases in which chloride contamination happens after the water have

been treated. In this case water aggressiveness increases exponentially until becoming more dangerous

that if it was not treated. Therefore pay attention when installing inverse osmosis systems in premises

used to salt food in the cells!!.

Passiving liquids are an efficient remedy against pitting only when the phenomenon is in its initial

phase and pitting is not very deep. These liquids (nitric acid) are capable or regenerating the destroyed

protection film; it is, though, absolutely necessary to eliminate first physically all the pitted zones by

removing the damaged metal. This liquids can be used on brat-pans wells, pasta cookers and pans. The

use of these liquids do not represent any advantage when used in case of stress corrosion or

intrecrystaline corrosion. Carry out the following operations:

1. Remove the damaged zones and pitting by smoothing so to create the smoothest possible surface,

wash and dry accurately.

2. Apply a thin film of passiving liquid (passivation creates by itself when entering in contact with

the air).

Demineralizing and deionizing systems are devices that “purify” completely water that becomes

free from any substance different from the base molecule H2O. The use of deonized water

enriched with orthophosphate sodium in 0,1% solution is indicated for indirect pans. Never used

pure deionized water since it is most aggressive on stainless steel. The orthophosphate sodium is a

corrosion inhibitor that increased the passivation of stainless steel which so becomes “tougher”

on corrosion; it is supplied with pan directly in the manufacturer premises. It is not necessary to

add it during the topping up but in case the cavity wall should be completely emptied it will need

to be replaced.

WATER SOFTENER type LT8 code 921305

The function of the water softeners is that of preventing the scaling; these machines change the calcium

(scaling) contained in the water with sodium that do get encrusted. The water softener is composed by

container for special porous resins which contain sodium deriving from the division of cooking salt.

Resins hold the magnesium and calcium carbonate and release sodium carbonate. When the sodium

contained in the resin is finished, the resin needs to be refill with sodium which must also be diffused

by means of a “regenerative” phase. Regeneration phase may be manual or automatic and is carried out

generally by adding common cooking salt in the special container. If resin regeneration is not carried

out regularly, the water upstream and downstream the water softener will be the same, as if were not

treated. It is convenient to install automatic water softeners so be sure that resins will be regenerated

automatically without depending on the operator.

The capacity of a water softener is expressed in litres of resin , the resin lasting time is more or less of

2000 regenerating cycles after which it should be changed; a litre of resin softens a variable quantity of

water according to hardness:

Consumption

H2O (Lt/H)

Hardness in °F H2O softened x

litre of resin

H2O softened

with 5,6 litres of

resin (Litres)

Regeneration

frequency (hours)

10 10 215 1200 120

20 10 215 1200 60

30 10 215 1200 40

10 20 200 1100 110

20 20 200 1100 55

30 20 200 1100 37

10 30 180 1000 100

20 30 180 1000 50

30 30 180 1000 33

10 40 160 900 90

20 40 160 900 45

30 40 160 900 30

10 50 140 800 80

20 50 140 800 40

30 50 140 800 26

10 60 125 700 70

20 60 125 700 35

30 60 125 700 23

When installing a water softener you need to install also a “Sterilization” system, that is to say an

electronic device that clean away bacteria and virus in the resins that deposit during the treatment. The

water softener LT8 code 921305 is supplied with its own sterilization system code 921306 .

All type of water softeners and specially ion exchange water softeners are often used incorrectly for

contrasting corrosion. In this point we need to be definitive: water softeners do not modify the water

aggressiveness. Therefore do not absolutely install water softeners if you have corrosion problems

since this systems function is only that of preventing scaling.

Which are the systems you will avoid installing

Electric/electronic and magnetic systems …

This type of systems are very common and there function is that of interacting with water molecules so

that scaling unites in more round forms which are easier to remove. They are absolutely not reliable if

the water temperature is over 60°C .

Chemical additives …

They are very common, there are also many types available; here by we indicated some of them :

• PH correctors

• Filming aliphatic polyamide for protecting piping against rust

• Polyphosphate descaling

All these products are toxic, produce foam that damage the oven’s electronic level regulators and in

any case are not reliable when water temperature is 60°C .

Electrolux 267712 (AOS101GTD1) Datasheet

Brand: Electrolux

Model: 267712 (AOS101GTD1)

Type: Datasheet

Here are some of the key features and benefits of the Electrolux 267712 (AOS101GTD1):

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Electrolux 267712 (AOS101GTD1) Datasheet

Electrolux 267712 (AOS101GTD1) Datasheet

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