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GB/T 10591-2006Specifications for high temperature / low air pressure testing chambers (English PDF)

高温/低气压试验箱技术条件

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Issued by

AQSIQ; SAC

Level / Type

National · Recommended

Issue date

April 3, 2006

Implementation date

October 1, 2006

Scope

GB/T 10591-2006 is the English-translated version of 高温/低气压试验箱技术条件.

China's national specification for the environmental test chamber that applies heat and reduced air pressure at the same time. The combination is worth a standard of its own because the two effects reinforce each other rather than cancelling out: at low pressure there is very little air left to carry heat away by convection, so a component that dissipates power runs far hotter than the air around it, and putting a high ambient on top of that produces the worst thermal case the equipment will ever meet. Anything intended for an aircraft, a high-altitude vehicle, a mountain radio site or an unpressurised cargo hold has to be shown to survive that case, and the only honest way to show it is to reproduce it. This standard specifies the terms and definitions, the recommended conditions of use, the technical requirements, the test methods, the inspection rules and the marking, packaging and storage of such chambers, and it applies to chambers used for high temperature and low air pressure testing of electrical and electronic products, of other products, and of parts and materials. It is one of a family of eight companion specifications covering the equipment a Chinese environmental laboratory owns - damp heat, salt spray, mould growth, low temperature damp heat, high and low temperature with low pressure, high and low temperature, and high temperature. The 2006 edition rewrote the 1989 text against IEC 60068-3-5, adding a terms and definitions clause, tightening the temperature fluctuation figure, requiring temperature data to be logged once a minute and moving the temperature performance test to the no-load condition. What a buyer gets from it is a common yardstick: two chambers from two makers that both claim 200 degrees C at 1 kPa can actually be compared, because the standard fixes how temperature deviation, gradient, fluctuation and rate of change are measured and what the limits are.

Document preview — GB/T 10591-2006

National Standard of the People's Republic of China

ICS: 19.040
Classification: N 04
Replacing: GB/T 10591-1989

Issued by: General Administration of Quality Supervision, Inspection and Quarantine; Standardization Administration of the PRC

1 Scope
2 Normative references
3 Terms and definitions
4 Recommended conditions of use
4.1 Ambient conditions
4.2 Power supply conditions
4.3 Load conditions
5 Technical requirements
5.1 Product performance
5.2 Requirements for the structure and the appearance of the product
5.3 Safety and environmental protection requirements
6 Test methods
6.1 Principal test instruments
6.2 Test conditions
6.3 Method of measuring the temperature
7 Inspection rules
8 Marking, packaging and storage
Annex A (informative) Method for identifying suspect data
Annex B (informative) Evaluation of the uncertainty of measurement of the technical performance of the test chamber

Foreword

GB/T 10591-2006 was issued on 3 April 2006 by the General Administration of Quality Supervision, Inspection and Quarantine and the Standardization Administration of the People's Republic of China, and has been in force since 1 October 2006. The /T in the designation marks it as a recommended national standard.

This standard is one of the series 'Specifications for environmental testing equipment'. The series consists of GB/T 10586-2006 Specifications for damp heat testing chambers, GB/T 10587-2006 Specifications for salt mist testing chambers, GB/T 10588-2006 Specifications for mould growth testing chambers, GB/T 10589-1989 Specifications for low temperature damp heat testing chambers, GB/T 10590-2006 Specifications for high and low temperature / low air pressure testing chambers, GB/T 10591-2006 Specifications for high temperature / low air pressure testing chambers, GB/T 10592-1989 Specifications for high and low temperature testing chambers and GB/T 11158-1989 Specifications for high temperature testing chambers.

From the date of its implementation this standard replaces GB/T 10591-1989 Specifications for high temperature / low air pressure testing chambers.

The main changes with respect to GB/T 10591-1989 are the following: a) a clause 'Terms and definitions' has been added, taking over the relevant content of IEC 60068-3-5; b) the concept of temperature fluctuation has been taken from IEC 60068-3-5 and the temperature fluctuation figure changed to 1 degree C (see Table 1); c) following the temperature data recording requirement of IEC 60068-3-5, data are now recorded once every minute (see 6.3); d) the test method for the rate of temperature rise has been revised in accordance with IEC 60068-3-5 (see 6.7); e) the range of atmospheric pressure in the conditions of use has been widened (see 4.1); f) a requirement for electrical insulation strength has been added (see 5.3.1); g) the test of the temperature performance is now carried out in the no-load condition (see 6.2.2); h) information on the method for evaluating the uncertainty of measurement of the temperature deviation and on its application has been added (see Annex B).

Annex A and Annex B of this standard are informative annexes.

This standard was proposed by the China Machinery Industry Federation and is under the jurisdiction of the Instrument and Meter Comprehensive Technical and Economic Research Institute of the machinery industry. The drafting was carried out by Chengdu Tianyu Test Equipment Co. Ltd., Chongqing Wanda Instrument Co. Ltd., the Fifth Electronics Research Institute of the Ministry of Information Industry and Chongqing Yinhe Test Instrument Co. Ltd.

1 Scope

This standard specifies the terms and definitions, the conditions of use, the technical requirements, the test methods, the inspection rules and the marking, packaging and storage of high temperature / low air pressure testing chambers (below referred to as 'testing chambers').

This standard applies to testing chambers used for carrying out high temperature and low air pressure tests on electrical and electronic products and other products, on parts and on materials.

2 Normative references

The provisions of the following documents become provisions of this standard through reference in this standard. For dated references, subsequent amendments (excluding corrections) or revisions do not apply to this standard; however, the parties to agreements based on this standard are encouraged to investigate whether the latest editions may be used. For undated references, the latest edition applies to this standard.

GB/T 191-2000 Packaging - Pictorial marking for handling of goods (eqv ISO 780:1997)

GB/T 14048.1-2000 Low-voltage switchgear and controlgear - Part 1: General rules (eqv IEC 60947-1:1999)

JB/T 9512-1999 Climatic environmental testing equipment and chambers - Determination of the noise sound power level

JJF 1059-1999 Evaluation and expression of uncertainty in measurement

3 Terms and definitions

The following terms and definitions apply to this standard.

3.1 test chamber: A closed cabinet or space in which some part is able to meet the specified test conditions.

3.2 temperature setpoint: The desired temperature set by means of the control device of the test chamber.

3.3 achieved temperature: After stabilization, the temperature at any point in the working space of the test chamber.

3.4 temperature stabilization: The condition in which the temperature at all points of the working space has reached the temperature setpoint and is held within the given tolerance range.

3.5 temperature fluctuation: After stabilization, the difference between the highest and the lowest temperature at any one point of the working space within a given interval of time.

3.6 working space: That part of the interior of the test chamber in which the specified conditions can be held within the specified tolerance.

3.7 temperature gradient: After stabilization, the largest value of the difference between the mean temperatures of any two points of the working space within any interval of time.

3.8 temperature rate of change: The rate of transition between two given temperatures measured at the centre of the working space, expressed in degrees C per minute.

3.9 temperature variation in space: After stabilization, within any interval of time, the difference between the mean temperature at the centre of the working space and the mean temperature at the other points of the working space.

3.10 temperature extremes: After stabilization, the highest and the lowest temperatures measured anywhere in the working space.

4.1 Ambient conditions

a) temperature: 15 degrees C to 35 degrees C; b) relative humidity: not greater than 85 per cent; c) atmospheric pressure: 80 kPa to 106 kPa; d) no strong vibration in the surroundings; e) no direct sunlight or direct radiation from other heat sources; f) no strong air currents in the surroundings, and where the surrounding air has to be forced into motion the air stream shall not blow directly onto the chamber body; g) no influence of strong electromagnetic fields in the surroundings; h) no high concentration of dust and no corrosive substances in the surroundings.

4.2 Power supply conditions

a) voltage: 220 V plus or minus 22 V, or 380 V plus or minus 38 V; b) frequency: 50 Hz plus or minus 0.5 Hz.

4.3 Load conditions

The load in the test chamber shall satisfy all of the following conditions at the same time: a) the total mass of the load placed in the working chamber shall not exceed 80 kg per cubic metre of working chamber volume; b) the total volume of the load shall not be greater than one fifth of the volume of the working chamber; c) on any cross-section perpendicular to the prevailing direction of air flow, the sum of the areas of the load shall not be greater than one third of the cross-sectional area of the working chamber at that place, and the load shall not be so placed as to obstruct the flow of air.

5.1 Product performance

The performance items and the corresponding figures for the test chamber are given in Table 1. The table sets ten items. The temperature ratings are 30, 40, 55, 70, 85, 100, 125, 155, 175 and 200 degrees C. The temperature deviation is plus or minus 2 degrees C for a test at normal pressure, and for a combined temperature and low pressure test it is plus or minus 3 degrees C up to 100 degrees C and plus or minus 5 degrees C above 100 degrees C and up to 200 degrees C, with the note that below 4 kPa the temperature deviation may be relaxed appropriately. The temperature gradient shall not exceed 2 degrees C and the temperature fluctuation shall not exceed 1.0 degrees C. The difference between the temperature of the inner wall of the working chamber and the temperature of the working space shall not be higher than 3 per cent of the working space temperature, expressed in K. The air pressure ratings are 84, 79.5, 70, 61.5, 55, 40, 25, 15, 8, 4, 2 and 1 kPa. The air pressure deviation is plus or minus 2 kPa from 84 kPa to 40 kPa, plus or minus 0.5 kPa from 25 kPa to 4 kPa and plus or minus 0.1 kPa at 2 kPa and below. The rate of temperature rise is calculated over each 5 min and the average rate shall not be greater than 1 degree C per minute, or else the fastest heating time shall be stated by the manufacturer in the product documents. The rate of change of air pressure shall not exceed 10 kPa per minute, and the air speed shall not exceed 1 m/s or shall be adjustable, with the adjustable range stated by the manufacturer in the product documents.

5.2 Requirements for the structure and the appearance of the product

5.2.1 The inner wall of the test chamber shall be made of a material that is heat resistant, not readily oxidised and of a certain mechanical strength.

5.2.2 The insulating material shall be able to withstand high temperature and shall be flame retardant.

5.2.3 The thickness of the insulating layer shall be such that the temperature of the parts of the outside of the chamber that are easily touched is not higher than 50 degrees C.

5.2.4 The heating elements shall not radiate directly onto the test specimen.

5.2.5 An observation window and a lighting device shall be provided.

5.2.6 Contamination of the air inside the chamber by the auxiliary devices of the test chamber and by the materials of the inner walls shall be avoided.

5.2.7 The sealing strip of the chamber door shall not age, become sticky, deform or lose its sealing property under high temperature conditions, and shall be easy to replace.

5.2.8 A device for test wiring shall be provided.

5.2.9 The external coating or plating shall be smooth and even in colour, without exposed base metal, peeling, blistering or scratch marks.

5.2.10 The specimen rack shall have a certain mechanical strength under high temperature conditions and shall be easy to load and unload.

5.3 Safety and environmental protection requirements

5.3.1 The insulation resistance between the wiring terminals and the metal enclosure of the chamber body shall be at least 2 megohm when cold and at least 1 megohm when hot, measured with a 500 V megohmmeter of accuracy class 1.0, and shall withstand a dielectric strength test at 1 500 V alternating current at 50 Hz applied for 5 s.

5.3.2 The protective earthing terminal shall have a good electrical connection with the enclosure of the test chamber and shall allow a firm and convenient connection to be made; it shall comply with 7.1.9 of GB/T 14048.1-2000.

5.3.3 Protection and alarm devices against over-temperature and over-current shall be provided.

5.3.4 The noise of the complete machine shall not be higher than 85 dB(A).

6.1 Principal test instruments

6.1.1 Anemometer: an anemometer whose sensitivity is not lower than 0.05 m/s.

6.1.2 Thermometer: a temperature measuring system made up of platinum resistance thermometers, thermocouples or similar temperature sensors, meeting the following requirements: the time constant of the sensor shall be 20 s to 40 s, and the expanded uncertainty of the temperature measuring system (k = 2) shall not be greater than 0.4 degrees C.

6.1.3 Surface thermometer: a measuring system made up of platinum resistance thermometers or similar sensors and meeting the following requirements: the time constant of the sensor shall be 20 s to 40 s, and the expanded uncertainty of the temperature measuring system (k = 2) shall not be greater than 1.0 degrees C.

6.1.4 Air pressure measuring instrument: a pressure gauge whose expanded uncertainty (k = 2) is not greater than one third of the permitted deviation of the air pressure being measured.

6.2 Test conditions

6.2.1 The test conditions shall meet the requirements of 4.1 and 4.2.

6.2.2 The test shall be carried out in the no-load condition.

6.3 Method of measuring the temperature

6.3.1.1 Three measuring planes, referred to as the upper, middle and lower layers, shall be defined within the working space of the test chamber. The distance between the upper layer and the ceiling of the working chamber is one tenth of the height of the working chamber; the middle layer passes through the geometrical centre of the working chamber; the lower layer is 10 mm above the lowest specimen rack. Note: where the working chamber has a sloping or pointed roof, the ceiling is taken to be the imaginary plane through the line of intersection between the sloping surface and the vertical surface.

6.3.1.2 The measuring points lie on the three measuring planes. The central measuring point is at the geometrical centre of the working chamber and the remaining measuring points are at a distance from the walls of the working chamber equal to one tenth of the respective edge length (Figure 1). For a test chamber whose working chamber volume is not greater than 1 cubic metre, however, that distance shall not be less than 50 mm.

6.3.1.3 Relationship between the number of measuring points and the volume of the working chamber: a) where the volume of the working chamber is not greater than 2 cubic metres, there are 9 temperature measuring points, arranged as in Figure 1; b) where the volume of the working chamber is greater than 2 cubic metres, there are 15 temperature measuring points, arranged as in Figure 2.

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.

Referenced standards

Normative references

GB/T 191-2000 Packaging - Pictorial marking for handling of goods (eqv ISO 780:1997)Graphical symbols marking for handling and storage of packages

GB/T 14048.1-2000 Low-voltage switchgear and controlgear - Part 1: General rules (eqv IEC 60947-1:1999) · JB/T 9512-1999 Climatic environmental testing equipment and chambers - Determination of the noise sound power level · JJF 1059-1999 Evaluation and expression of uncertainty in measurement

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