GOST 29006-91

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  ГОСТ 29006-91

GOST 29006−91 (ISO 4491−3-89) Powder metal. Method for the determination of hydrogen-reducible oxygen

GOST 29006−91
(ISO 4491−3-89)

Group B59

INTERSTATE STANDARD

POWDER METAL

Method for the determination of hydrogen-reducible oxygen

Metallic powders. Method for determination of hydrogen-reducible oxygen

MKC 77.160
AXTU 1709

Date of introduction 1992−07−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Academy of Sciences of the Ukrainian SSR

DEVELOPERS

V. N. Klimenko, PhD. tech. Sciences; A. E. kushchevsky, PhD. chem. Sciences; V. A. Dubok, PhD. chem. Sciences (head of subject); V. I. Kornilov, candidate. chem. Sciences; V. V. Garbuz, PhD. chem. Sciences; T. F. Mozol, I. M. Kryachek

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee on management of quality and standards from 13.05.91 N 668

Annex 2 of this standard prepared by the direct application of international standard ISO 4491−3-89* «Metal powders. Determination of oxygen content by methods of recovery. Part 3. The hydrogen-reducible oxygen"
________________
* Access to international and foreign documents referred to here and hereinafter, can be obtained by clicking on the link to the site shop.cntd.ru. — Note the manufacturer’s database.

3. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

4. REPRINTING. August 2004


This standard specifies a method for the determination of hydrogen-reducible oxygen, with the mass fraction of oxygen from 0.05% to 3%.

The standard covers powders, not alloyed, low-alloy, high-alloy metals containing carbon.

The standard does not apply to powders containing additives sublimating metals, lubricants and organic additives.

Recommendations on the choice of method for the determination of oxygen in metal powders is given in Appendix 1.

Allowed to carry out the determination of hydrogen-reducible oxygen, according to the international standard ISO 4491−3-89 given in Appendix 2.

The method is based on the aging of the pre-dried metal powder at a prescribed temperature and time in a flow of dry hydrogen and the measurement of the mass of the oxygen is recovered as water vapor.

To determine the mass of water vapor using them absorption of absolute methanol and titration with Karl Fischer reagent.

For powders containing carbon, use conversion of carbon oxide (II) oxide carbon (IV) water and methane by a Nickel catalyst.

Allowed to determine the mass fraction of oxygen to use other methods to ensure the metrological characteristics are not below those obtained by titration with Karl Fischer reagent.

1. GENERAL REQUIREMENTS

1.1. Mass fraction of oxygen in the alloy powder determined in two (or more) parallel batches.

The result of the analysis taking the arithmetic mean of two (or more) of parallel measurements at p = 0.95.

1.2. Sampling — according to GOST 23148.

The weight of the portion of the sample is determined in accordance with table.1.

Table 1

1.3. Weighing of batches is carried out with an uncertainty of less than 0.1 mg if, in the normative-technical documentation does not specify other values.

2. EQUIPMENT

Laboratory scales for General purpose according to GOST 24104* 2nd accuracy class with the largest weighing limit of 200 g or any other scale that meets the specified requirements for their metrological characteristics.
_______________
* From 1 July 2002 was put into effect GOST 24104−2001.


Installation for determination of hydrogen-reducible oxygen, (hell.1, 2) consists of:

Damn.1

Damn.2

the source of nitrogen (1), is provided with a gas reducer with flowmeter and regulator gas flow;

the source of hydrogen (2), is provided with a gas reducer with flowmeter and regulator gas flow rate, supplying gas at a rate between 20 and 35 DM/h;

the hydrogen purification device (3) containing a catalytic reducing agent (titanium sponge, copper deposited on silica gel, etc.) and a desiccant;

— three-way tap (4);

d (5);

— recovery gas-tight tubes (6) made of quartz in accordance with the requirements of one of the two active schemes for the restoration:

a) sealed one side of the quartz tube with an inner diameter of 27 mm to 30 mm and length 400 mm, open end which is gas-tight split coupling two pipes with a diameter of 5 to 6 mm and a length of from 60 to 80 mm, the other from 200 to 240 mm (allowed length is 400 mm) (Fig.1, 3);

Damn.3

b) a quartz tube, open on two sides, with inner diameter 20 mm, length up to 1000 mm with a releasable seal at the ends for entrance and exit of gas (damn.2, 3);

oven for drying (7) and the furnace for recovery of metal powder (8) with control systems for maintaining a predetermined temperature in the zones of location of the boats with the batches. Allowed the use of a single two-zone furnace, combining the functions of drying and recovery;

pumps (9), made of ceramics based on aluminum oxide, having a smooth surface and sizes, sufficient to fill no more than halfway. It is recommended to use in the analysis of boat BOS 2 or BOS 3 according to GOST 9147. Pumps should be calcined in hydrogen at a temperature of from 900 °C to 1100 °C for at least 1 h and stored in a desiccator;

connection of the bypass (10) used to protect the catalyst from contact with air in the case, if the conversion device is not connected;

— conversion device (11) consisting of a glass tube filled with Nickel catalyst, and furnace control system for maintaining temperature of 380 °C. the conversion Device must be permanently filled with hydrogen;

— burettes (12) with a capacity of 25 cmwith a scale division of 0,05, protected from the ingress of atmospheric moisture by a glass tube filled with desiccant;

detector (13) for the determination of the titration end point;

— flasks for titration (14) with a capacity of from 200 to 300 cmwith a magnetic stirrer. Bulb, if necessary, provided with two platinum electrodes.

3. REAGENTS AND MATERIALS

Methanol dehydrated with GOST 6995.

The Karl Fischer reagent with the equivalent of 1 mg of oxygen per 1 cmof the reagent. The mass concentration of Karl Fischer reagent is determined according to GOST 18317.

Hydrogen with a mass fraction of oxygen is not more than 0.005% with a dew point not exceeding -45°C.

Nitrogen or other inert gas with a mass fraction of oxygen is not more than 0.005% with a dew point not exceeding -45°C.

Drying means: alumino-silicate of sodium, anhydrous, granular, activated silica gel or magnesium perchlorate (angeren).

4. PREPARATION FOR ASSAY

4.1. The installation is collected in accordance with the devil.1 and 2 for methods 1 and 2. To install the method 1 regenerative tube set in the oven for drying (7).

4.2. For each testing method and each type of powder was experimentally select the temperature and duration of the test until the complete recovery of powders.

In table.2 shows the approximate temperature recovery of the powders at the time of exposure not less than 20 min.

Table 2

4.3. Drying of powders is carried out at a temperature of (170±10)°C for 20 min in a current of inert gas at a rate of 30 DM/h.

4.4. Set the required temperature recovery in the recovery furnace (8).

4.5. Wash out the burette (12) the Karl Fischer reagent to exclude the change in the mass concentration of the reagent from moisture in the burette. Fill the burette with Karl Fischer reagent.

4.6. Pour the methanol in a flask for titration (14) so that the level of methanol was above the level of the exit tube of the gas and electrodes (if applicable electrochemical detector); include the stirrer and titrated with Karl Fischer reagent to the visual point neutralize possible traces of water in methanol.

4.7. If you use electrochemical detection of the equivalence point (Fig.4) at the bottom of the electrode detector switch (3) and setting resistor (1) so that the current microammeter (2) was equal to 120 And, simultaneously de-energised electrodes.

Damn.4

4.8. For methods 1 and 2 establish a flow of inert gas (Fig.1 and 2) at a rate of 30 DM/h and maintain it for at least 10 min. then with a crane (4) switch the flow of inert gas to hydrogen flow and set the flow rate of 25 DM/h.

For method 1 insert a tube into the oven restore and leave it for 10 minutes, Switch the flow of hydrogen to the inert gas. Take out the recovery tube and cooled to room temperature.

4.9. Titrate the methanol to the visual equivalence point for the neutralization of traces of water.

4.10. To check the integrity and efficiency of the installation of spend control experience. A control experiment is conducted for each series of definitions with an empty boat in the conditions described in sec. 5. If the result is greater than 1 mg of oxygen or the results are different, the equipment is subjected to leak.

5. ANALYSIS

5.1. For methods 1 and 2 if necessary, connect the conversion device, set the temperature (380±10)°C. Conversion device include at the time of entry of boats into the recovery zone of the furnace. When using a conversion device is necessary to ensure that at the time of connection it was filled with dry hydrogen.

The conversion device can not be used, if mass fraction of carbon in the metal powder is less than 3% of the mass fraction of oxygen.

5.2. Method 1

Recovery open the phone and put it in a boat with a hitch. Shut up and blow dried with an inert gas at a flow rate of at least 30 DM/h for 10 min to remove the air introduced with the charge.

Titrate the methanol to the visual equivalence point. Set the inert gas stream at a rate of 30 DM/h, and insert a recovery tube into the oven drying temperature (170±10)°C. After drying the methanol is titrated to the equivalence point, determined either visually or by an electrochemical detector. Record the volume of Karl Fischer reagent in the burette and the drying time.

With the help of a crane (4) switch the flow of inert gas to hydrogen flow, the flow rate of hydrogen 25 DM/h, and put the phone in recovery furnace in which the desired temperature. After recovering the methanol is titrated to the equivalence point. Record the volume of Karl Fischer reagent.

With the help of a crane (4) switch the flow of hydrogen to the inert gas stream. Remove the tube from the oven, cooled to room temperature (use a fan), open the receiver and remove the boat with the powder.

5.3. Method 2

Set the temperature in drying and reducing zones of the furnace (8), blow the drying tube (6) is dried with an inert gas, then open and put it in a boat with a hitch. With a hook of stainless steel, introduced into a recovery tube using a movable gas-tight seal, move the boat in a reducing zone of the furnace. After recovery is completed, titrate the methanol with Karl Fischer reagent. Record the volume used reagent.

Switch the flow of hydrogen to the inert gas stream. Move the boat in a low-temperature zone of the furnace and after 1 min remove it from the tube.

Spend two (or more) dimensions. The number of measurements should be specified in the normative-technical documentation for the particular powder.

Note. In mass analysis can be placed in the area of kiln drying some samples and moving them through a two-zone furnace, accumulating the output.

6. PROCESSING OF THE RESULTS OF THE ANALYSIS

6.1. Fraction of total mass of hydrogen-reducible oxygen, () percentage calculated by the formula

,

where is the mass concentration of the reagent, Karl Fischer, mg/cm;

 — the volume of Karl Fischer reagent consumed for titration of sample, cm;

 — the volume of Karl Fischer reagent consumed for titration in the control experiment, cm;

 — weight of sample, mg.

6.2. The absolute discrepancy between two parallel definitions should not exceed permissible values (at p = 0.95) shown in table.3.

Table 3

7. PROTOCOL ANALYSIS

Protocol analysis should include:

— name, type, brand, samples of the powder;

— the time and temperature of drying;

— time and temperature recovery;

— the results of individual determinations and the average oxygen content;

— information on the application of the conversion device;

— information on transactions not specified in the standard, which may influence the results of determinations;

— the designation of this standard.

ANNEX 1 (reference). RECOMMENDATIONS ON THE CHOICE OF METHOD FOR THE DETERMINATION OF OXYGEN IN METAL POWDERS

ANNEX 1
Reference

1. When measuring the oxygen content of the metal powder in the practice of powder metallurgy is usually used three methods of measurements:

— determination of the mass loss during annealing in hydrogen;

— determination of hydrogen-reducible oxygen;

— determination of content of total oxygen by the method of reductive extraction of carbon.

For the correct choice of method of measuring the oxygen content must consider the following:

1.1. In terms of measuring the mass loss during annealing in hydrogen at a temperature of 1000 °C — 1200 °C fully restores only a portion of the metal oxides present in the metal powder in the form of random or dopants (e.g. oxides of copper, iron, cobalt, Nickel, tin, lead, tungsten, molybdenum). The oxides of such metals as chromium, manganese, vanadium, titanium recovered partially. Oxides of alkali, alkaline earth, most rare earth metals, aluminum, silicon, zirconium and others in hydrogen is not practically restored. This leads to the smaller value of the mass loss on ignition compared with the total oxygen content and the dependence of this quantity on the conditions of recovery.

The metalloids contained in the metal powder (carbon, nitrogen, sulfur, phosphorus), while restoring the hydrogen can react with hydrogen or with oxides contained in the powder, forming volatile compounds, which gives additional contribution to the measured mass loss during annealing in hydrogen.

The carbon contained in the metal powder, can recover part of the oxides, not recoverable hydrogen that leads to the dependence of the measured mass loss during annealing in hydrogen on the carbon content.

Impurity metals with a greater affinity to oxygen (chromium, aluminium, zirconium, titanium, etc.) may be partially oxidized during the annealing in hydrogen as due to the traces of hydrogen and moisture present in the hydrogen and oxygen associated with legkovozvodimykh oxides. The consequence of this is underestimation of the measured value or even increase in the weight of the metal powder during annealing in hydrogen.

Because of these reasons the magnitude of the mass loss during annealing in hydrogen is only conditionally can be considered as a measure of oxygen content in metallic powders and the application of this method requires detailed analysis of possible changes in the composition of powder and accurate reproduction of the conditions of the definition.

1.2. Measurement of the content of the hydrogen-reducible oxygen, to eliminate the influence of metalloids, sublimating impurities, carbon and determine the amount of oxygen in the metal powder, which interacts with hydrogen in the conditions of recovery.

This method is also impossible to determine the amount of oxygen that is included on hardly-cracked oxides, rare earth and other metals contained in the analyzed powder in the form of inclusions, or impurities. However, in this method eliminates the error associated with the presence of carbon using the conversion device is transferred to the reactions , into methane and water, titmouse using Karl Fischer reagent.

3. The method of reductive extraction of oxygen by melting the metal powder at a temperature of 2000 °C — 2500 °C in a graphite crucible in a stream of inert gas allows to determine the total oxygen content, regardless of its location in the metal powder in the form of adsorbed gas films and inclusions of oxides and hydroxides of any composition, a solid solution of oxygen in the metal.

The disadvantage of this method is its relative nature — the oxygen content is determined relative to a standard sample.

If in the method of reductive melting is used coulometric check carbon oxide (II), after its oxidation to carbon monoxide (IV) and in the analyzed powder contains impurities metalloids sulphur, phosphorus, nitrogen, the results may be inflated due to the formation of oxides of metalloids. These errors are almost completely eliminated by the complexity of the installation by introducing absorbing substances. Chromatographic and IR spectrometric methods check carbon monoxide impurities are metalloids do not affect the results of the analysis.

Understatement of the results of determination of oxygen by the method of reductive melting is possible in those cases when the analyzed powder are easily sublimating metals or oxides, which congenerous on the cold parts of the gas path and partially adsorb the carbon monoxide. However, for the powders of the metals of concern, this phenomenon is not observed.

For control of correctness of determination of oxygen recovery by extraction and calibration standard samples using more sophisticated, although direct methods for the determination of oxygen, such as mass spectrometry and neutron activation.

APPENDIX 2 (recommended). INTERNATIONAL STANDARD ISO 44491−3-89. THE METAL POWDERS. DETERMINATION OF OXYGEN CONTENT BY METHODS OF RECOVERY. PART 3. THE HYDROGEN-REDUCIBLE OXYGEN

ANNEX 2
Recommended

POWDER METAL

DETERMINATION OF OXYGEN CONTENT BY METHODS OF RECOVERY

PART 3

THE HYDROGEN-REDUCIBLE OXYGEN

1. Appointment

This part of ISO specifies a method for the determination of hydrogen-reducible oxygen in the metal powders containing 0,05% () 3% () oxygen.

The method is applied to unalloyed, partially or completely doped metal powders and also to mixtures of carbides and binder metal. It does not apply to powders containing the lubricant or organic fillers.

Application of the method can be extended to powders containing carbon, using a special catalyst.

This part of ISO 4491 should be used in conjunction with ISO 760 (GOST 18317) and ISO 4491−1.

2. Links

The following standards contain provisions used in this part of ISO 4491. Their products have been useful when publishing. Since all standards are reviewed, the creators of this document have used the latest products the below standards. Members of ISO and IEC maintain sound proposals for the development of international standards.

ISO 760−78 the Definition of water. Karl Fischer method (General method)

ISO 4491−1-89 Powder metal. Determination of oxygen content by methods of recovery. Part 1. General management

3. The essence of the method

Pre-processing the test sample by drying at a low temperature (170°C) in dry nitrogen.

The recovery in the flow of dry hydrogen at a given temperature. Absorption in methanol of the water formed by the reaction of oxides with hydrogen. The titration with Karl Fischer reagent, wherein the endpoint is determined visually by change of color or electrometrically two electrodes (point final stop).

For powders containing carbon, conversion of the resulting monoxide and carbon dioxide to methane and water at a temperature of 380 °C takes place with the help of Nickel catalyst.

4. Reagents

For the analysis use only reagents of known analytical grade and only distilled water or water of equivalent purity.

A note of caution. The Karl Fischer reagent contains four toxic component: iodine, sulfur dioxide, pyridine and methanol. It is important to avoid direct contact and inhalation especially. If there is accidental contact, it should be copious flushing with water.

4.1. Methanol, anhydrous.

4.2. The Karl Fischer reagent equivalent to 1 mg of oxygen per milliliter.

The titer of the Karl Fischer reagent is determined using one of the following methods:

a) is poured into the titration flask from 20 to 30 mg of water weighed with an accuracy of 0.1 mg;

b) add 100 to 200 mg, weighed with an accuracy of 0.1 mg of the dihydrate of sodium Vinokurova (certifikovany substances with the theoretical water content of 15.66% (), corresponding of 13.92% () oxygen), pre-milled to fine powder and dried at a temperature of (105±5)°C to constant weight;

C) apply the method given in clause 7, using from 100 to 200 mg of pure sodium dihydrate Vinokurova, weighed with an accuracy of 0.1 mg, as the test sample, but stopping at the stage of drying at a temperature of 170 °C and subsequent titration.

Cm. ISO 760 for a more detailed description of standard procedures.

4.3. Hydrogen, having a maximum oxygen content of 0,005% () and dew point not exceeding -45°C.

4.4. Nitrogen or argon, having a maximum oxygen content of 0,005% () and dew point not exceeding -45°C.

4.5. A desiccant consisting of granular anhydrous aluminium-sodium silicate, activated silica gel or magnesium perchlorate.

5. Equipment

Note. The installation diagram given on features.1 (method 1) and hell.2 (method 2).

5.1. The unit supplying the hydrogen (A) having the pressure-relief valve, control valve and flow meter.

5.2. Cleaner (In) for hydrogen containing a catalytic deoxidizer and desiccant.

5.3. Feeder of nitrogen (or argon) (With) having the pressure-relief valve, control valve and flow meter.

5.4. Valve switching strip (D).

5.5. Device for final drying of the gas (E), containing desiccant.

5.6. The recovery tube (F), not passing gas, made of quartz corresponding to one of the specifications:

a) a tube, sealed at one end, with an internal diameter of 27 to 30 mm, a length of about 400 mm with two smaller quartz tubes of diameter 5 to 6 mm and length: from 60 to 80 mm, the other from 200 to 240 mm, located as shown on the devil.3. This device is first introduced into a drying and then in a reducing furnace;

b) a tube with open ends, an inner diameter of about 20 mm, length 1 m, with an entrance and exit for gas. This tube is permanently located in the two furnaces.

5.7. Two furnaces (G), one for drying the test samples and the other for oxide reduction, with temperature control capable of maintaining temperature within the specified limits in the part of tube where there is a boat.

Note. Use one furnace that performs both the functions of drying and recovery.

5.8. Boat (N) is preferably high-alumina ceramic with polished surface and of a size such that the test sample in the filled condition did not exceed half its volume. The boat is placed in hydrogen at a temperature of from 900 °C to 1100 °C for at least 1 h, and then kept prior to use in the dryer.

5.9. Device conversion catalyst (I) consisting of a glass tube filled with Nickel catalyst, and a furnace with temperature control system capable of maintaining the temperature in the glass tube 380 °C. the conversion Device must be constantly filled with hydrogen.

5.10. The direct circuit (J), arranged so that air had access to the catalyst.

5.11. Titration flask (K) with the capacity from 200 to 300 cmwith a magnetic stirrer and an equivalent device, equipped with two platinum electrodes in case of electrometric determination of the titration end point.

5.12. Detector the end point (L) is used for the electrometric determination of the end point.

5.13. Burette (M), with a capacity of 25 cmwith a scale of 0.05 cm, protected from moisture environment with a safety tube filled with desiccant (n.4.5).

Allowed the use of equipment is given in PP.5.11, 5.12 and 5.13, as well as any industrial equipment, if it has a titration apparatus, Karl Fischer, subject to the requirements of ISO 760.

6. Sampling

The powder must be examined in the delivery condition.

7. The test procedure

7.1. The test sample

The mass of the test samples, weighed with an accuracy of 0.1 mg, taken in accordance with table.4 depending on the anticipated oxygen content.

Table 4

7.2. Test conditions

For each type of equipment and each type of powder to experimentally determine the optimum temperature and time for full recovery.

Are given in table.5 temperature recovery are help. Recovery duration 20 min.

Table 5

In the same way to determine the optimal drying time at 170 °C in dry nitrogen.

7.3. Training equipment

7.3.1. Gather the installation diagram, as shown in hell.1 for method 1 or in hell.2 for method 2. Set the temperature recovery in the recovery furnace. While for method 1 the recovery pipe leave outside the oven.

7.3.2. Wash out the burette with Karl Fischer reagent to ensure no moisture, which may alter the titer of the reagent. Pour out the remnants and fill the burette with Karl Fischer reagent.

7.3.3. Fill the titration flask with methyl alcohol so that the introductory tube (and the electrodes, if any) was below the liquid surface. Include the stirrer and titrated with Karl Fischer reagent to the visual end point of titration to neutralize the traces of water in methanol.

7.3.4. If you use the electrometric determination of the end point of the titration (see the devil.4) then short the electrodes of the switch S electrometric detector, the end point of the titration and the adjustment of the variable resistance R set at the microammeter N a current of 120 A. Again include the switch 's.

7.3.5. For both methods regulate the flow rate of nitrogen, which must be not less than 30 DM/h time course — 10 min. Switch the gas flow from nitrogen to hydrogen by using the gas selection valve and set the flow rate of about 25 DM/h.

For method 1 insert a recovery tube in the recovery oven and leave for 10 minutes, Switch the gas flow back on the nitrogen. Remove the tube and cool to room temperature.

7.3.6. Re-titrate the methanol to the visual end point of titration to neutralize the traces of water formed during the test.

7.3.7. Check the condition and sealability of the apparatus, conducting the blank described in claim 7.4.

A note of caution. Do not turn off the flow of hydrogen until then, until the tube is hot, except in the case of switching the flow of hydrogen to nitrogen.

7.4. Blank

For each series of definitions spend idle experience with the use of empty boats subject to the same test procedure as for the test samples.

Note. Serviceable equipment gives the result of test experiment, approximately 1 mg of oxygen at heating time 20 min. If the result is much higher or the results are different, then you should check the installation for leaks.

7.5. Definition

In both methods, to avoid the impact of the carbon include device conversion catalyst, pre-heated to a temperature of (380±10)°C, and is connected to the system before you put the boat in the recovery zone.

At the end of the definition is necessary to ensure that the device conversion catalyst has not been turned off prior to switching the flow of hydrogen to nitrogen.

Note. If necessary, you can determine the moisture content of the sample, recording the volume of Karl Fischer reagent used to titrate water formed during drying.

7.5.1. Method 1. The recovery tube with a closed end

Open the recovery tube and insert the boat containing the weighed samples of the investigated powder. Up close and blown dry with nitrogen with a minimum speed of 30 DM/h to remove air trapped together with the investigated sample. If the purge has not been set in advance, it is necessary to purge 10 min.

The methanol is titrated to a visual end point of titration. Set the nitrogen flow at the rate of 25 DM/h and placing the tube in an oven at a temperature of (170±10)°C. At the end of the drying period the methanol is titrated to the end point, which is determined visually or using the electrometer detector in accordance with the requirements given in clause 7.3.4. Record the volume of Karl Fischer reagent in the burette and during drying. Using a crane to change the flow of nitrogen to hydrogen by setting a flow rate of 25 DM/h, and put a tube in a reducing furnace in which the temperature of recovery. At the end of recovery the methanol is titrated to the end point of the titration, defining it in the same way as was presented earlier. Record the readings of the burette and record the volume of titration , sm. Record the recovery time. Change the gas flow from hydrogen to nitrogen and remove the tube from the oven. Cool the tube to room temperature, using a fan, then open the receiver and remove the boat.

7.5.2. Method 2. The recovery tube with open end

You must make sure that the furnace temperature is set correctly. Purged with dry nitrogen, and then open the recovery tube and insert the boat with the studied sample. With a hook of stainless steel with a hermetic seal pushed the boat into the drying zone. After drying titrate the methanol with Karl Fischer reagent.

Change the nitrogen flow to hydrogen and pushing the boat in a zone of high temperature reducing furnace. At the end of the recovery period is titrated with Karl Fischer reagent. Record the volume of reagent, cm.

Changing the flow of hydrogen to nitrogen. Move the boat in an area of low temperature and, after 1 min, remove it from the oven.

8. Expression of results

8.1. The content of the hydrogen-reducible oxygen (rest.), expressed as a percentage by mass, determined by the formula

,

where  — titer Karl Fischer reagent, mg/cm;

 — the volume of Karl Fischer reagent used for the studied sample, cm;

 — the volume of Karl Fischer reagent used for the baseline test, cm;

 — mass of test sample, mg.

8.2. The discrepancy between the results of two (or more) of the definitions shall not exceed the maximum permissible values given in table.3.

If the results are satisfactory, the average value is rounded as specified in table.6.

If the difference exceeds the maximum permissible value, then the test is repeated, paying particular attention to the reproducibility control test, recovery time and all other specified warnings.

Table 6

9. Test report

The test report should include:

a) a reference to this part of ISO 4491;

b) all details necessary for identification of the test sample;

C) drying time and temperature;

g) the recovery time and temperature;

d) were the conversion device with the catalyst;

e) the average value of the results obtained;

g) any operation not specified in this standard or in standards referenced, as well as any operations that are considered as optional;

h) any incidental moments that could affect the results.

A device supply of hydrogen; To clean; With — the feeder of nitrogen or argon; D — gas switching valve; E — the device for final drying of gas; F — recovery tube; G — furnace; H — boat, I — device conversion catalyst; J — video scheme; To — the titration flask; L detector the end point of the titration; M — burette

Damn.1. Schematic view of a device according to method 1

A device supply of hydrogen; To clean; With — the feeder of nitrogen or argon; D — gas switching valve; E — the device for final drying of gas; F — recovery tube; G — furnace; H — boat, I — device conversion catalyst; J — video scheme; To — the titration flask; L detector the end point of the titration; M — burette

Damn.2. Schematic view of a device according to the method 2

F — recovery tube; H — boat

Damn.3. Examples of the recovery tubes

N — microammeter; R — resistor; S, switch

Damn.4. Schematic diagram of the detector of the end point