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GB/T 10590-2006Specifications for high and low temperature / low air pressure testing chambers (English PDF)

高低温/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 10590-2006 is the English-translated version of 高低温/低气压试验箱技术条件.

China's national specification for the combined high and low temperature with low air pressure testing chamber - the altitude chamber, which reproduces together the temperature and the reduced pressure found at height. Combining the two conditions is the whole point of the machine, because they interact and testing for each of them separately misses most of what actually goes wrong: at low pressure there is little air left to carry heat away, so a component that runs cool at sea level overheats even though the surrounding air is colder, the dielectric strength of air falls so that a clearance which insulates on the ground flashes over above it, sealed assemblies burst or leak as the differential rises, and liquids boil at temperatures they would never reach otherwise. Anything meant for aircraft, for high-altitude vehicles or for equipment carried by air has to be proved in a chamber of this kind before it is allowed near a real aeroplane. The standard belongs to the family of specifications for environmental testing equipment, alongside the damp heat, salt mist, mould growth and high temperature chambers, and it is the document a laboratory quotes when it buys such a chamber and the document an inspector uses when he checks that the chamber does what its plate says. It fixes the classes of temperature and of air pressure the chamber may be built to, the deviations and fluctuations allowed at each of them, the gradient across the working space, the rates at which temperature and pressure may be changed, and the air speed - and it fixes them for the combined condition, which is always the harder one, since with the air thinned out the usual forced convection barely works. To those it adds the requirements on the construction of the chamber, the insulation, the door seals that must not harden in the cold, the refrigeration circuit, the electrical safety of a heated vessel that is also being evacuated, and the noise. Finally it sets out the test methods, from the placing of the measuring points inside the working space to the arithmetic by which each figure is worked out, so that two laboratories measuring the same chamber arrive at the same number. Issued on 3 April 2006 and in force since 1 October 2006, it replaced GB/T 10590-1989 and GB/T 11159-1989.

Document preview — GB/T 10590-2006

National Standard of the People's Republic of China

ICS: 19.040
Classification: N 04
Replacing: GB/T 10590-1989, GB/T 11159-1989

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 Conditions of use
4.1 Ambient conditions
4.2 Power supply conditions
4.3 Water supply conditions
4.4 Test load conditions
5 Technical requirements
5.1 Performance of the product
5.2 Requirements on the structure and the appearance of the product
5.3 Safety and environmental protection requirements
6 Test methods
6.1 Main measuring instruments
6.2 Test conditions
6.3 Method for testing the temperature
7 Inspection rules
8 Marking, packaging and storage
A Annex A (informative) Method for identifying doubtful data
B Annex B (informative) Evaluation of the uncertainty of the measurement of temperature deviation

Foreword

This standard is one of the series of specifications for environmental testing equipment. The series is made up 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 and damp heat 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 it comes into force this standard replaces GB/T 10590-1989 Specifications for low temperature / low air pressure testing chambers and GB/T 11159-1989 Specifications for low air pressure testing chambers.

The main differences from GB/T 10590-1989 and GB/T 11159-1989 are the following: a) a chapter on terms and definitions has been added, taking its content from the relevant part of IEC 60068-3-5; b) following the concept of temperature fluctuation of IEC 60068-3-5, the temperature fluctuation figure has been changed to 1 degree C (see Table 1); c) following the temperature data recording requirement of IEC 60068-3-5, the data are now recorded once every minute (see 6.3); d) the method for testing the rate of temperature change has been revised in line with IEC 60068-3-5 (see 6.6); e) the range of atmospheric pressure in the conditions of use has been widened (see 4.1); f) the working temperature classes of the product have been adjusted slightly, with a low temperature class of minus 30 degrees C added and the high temperature class of 200 degrees C removed (see Table 1); g) the temperature deviation figures are now graded according to the air pressure (see Table 1); h) a requirement on the quality of the cooling water has been added (see 4.3 c)); i) a requirement on electric insulation strength has been added (see 5.3.1); j) the testing of the temperature performance is now carried out with the chamber empty (see 6.3.2); k) a method for evaluating the uncertainty of the measurement of temperature deviation, and information on its application, have 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 administration of the Instrument and Meter Comprehensive Technical and Economic Research Institute of the machinery industry. It was drafted by Chongqing Wanda Instrument Co., Ltd., Chengdu Tianyu Test Equipment Co., Ltd., the Fifth Electronics Research Institute of the Ministry of Information Industry and Chongqing Yinhe Test Equipment Co., Ltd. The main drafters are Chen Yunsheng, Que Zhengxin, Lai Wenguang and Xu Qinglu.

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 and low temperature with low air pressure testing chambers, referred to below as the test chamber.

This standard applies to test chambers used to carry out high and low temperature with low air pressure tests on electrical and electronic products, on other products, on components and on materials.

2 Normative references

The provisions of the following documents become provisions of this standard through being referred to in it. For dated references, later amendments (excluding corrections) or revisions do not apply; however, the parties to an agreement based on this standard are encouraged to examine whether the latest editions of those documents may be used. For undated references, the latest edition applies.

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 - General rules (eqv IEC 60947-1:1999)

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

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, some part of which 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 stabilisation, the temperature at any point within the working space of the test chamber.

3.4 temperature stabilization: the condition in which the temperature at every point of the working space has reached the temperature setpoint and is held within the given tolerance.

3.5 temperature fluctuation: after stabilisation, the difference between the highest and the lowest temperature at any one point of the working space during a given interval of time.

3.6 working space: the part of the test chamber within which the specified conditions can be maintained inside the specified tolerances.

3.7 temperature gradient: after stabilisation, the greatest value of the difference between the mean temperatures of any two points of the working space during a given 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 and expressed in degrees C per minute.

3.9 temperature variation in space: after stabilisation, the difference during a given interval of time 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 stabilisation, the highest and the lowest temperatures reached within the working space.

4.1 Ambient conditions

a) temperature: 15 degrees C to 35 degrees C; b) relative humidity: not greater than 85 %; c) atmospheric pressure: 80 kPa to 106 kPa; d) no severe vibration and no corrosive gas in the surroundings; e) no direct sunlight and no direct radiation from other sources of heat or cold; f) no strong air currents in the surroundings, and where the surrounding air has to be moved by force, the air stream shall not blow directly onto the body of the chamber; g) no magnetic field in the surroundings capable of disturbing the control circuits of the chamber; h) no high concentration of dust and no corrosive substances in the surroundings.

4.2 Power supply conditions

a) alternating voltage: 220 V +/- 22 V or 380 V +/- 38 V; b) frequency: 50 Hz +/- 0.5 Hz.

4.3 Water supply conditions

Mains water or recirculated water meeting the following conditions should be used: a) water temperature: not higher than 30 degrees C; b) water pressure: 0.1 MPa to 0.3 MPa; c) water quality: in accordance with the standard for industrial water.

4.4 Test load conditions

The load of 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 for each cubic metre of its volume; b) the total volume of the load shall not exceed 1/5 of the volume of the working chamber; c) on any cross-section perpendicular to the main direction of the air flow, the sum of the areas of the load shall not exceed 1/3 of the cross-sectional area of the working chamber at that point, and the load shall not be so placed as to obstruct the flow of the air.

5.1 Performance of the product

The performance items of the test chamber and the figures required of them are given in Table 1.

Table 1 gives, item by item: the temperature classes, which are 30, 40, 55, 70, 85, 100, 125, 155 and 175 degrees C on the high side and 5, minus 5, minus 25, minus 30, minus 40, minus 55 and minus 65 degrees C on the low side; the temperature deviation, which is +/- 2 degrees C in a temperature test at normal pressure and, in a combined temperature and low pressure test, +/- 3 degrees C up to 100 degrees C and +/- 5 degrees C above 100 degrees C and up to 200 degrees C; the temperature gradient, not more than 2 degrees C; the temperature fluctuation, not more than 1.0 degrees C; the difference between the temperature of the inner wall of the working chamber and the temperature of the working space, which shall not exceed 3 % of the chamber temperature in the high temperature classes and 8 % of it in the low temperature classes; the air pressure classes, which are 84, 79.5, 70, 61.5, 55, 40, 25, 15, 8, 4, 2 and 1 kPa; the air pressure deviation, which is +/- 2 kPa from 84 kPa to 40 kPa, +/- 0.5 kPa from 25 kPa to 4 kPa and +/- 0.1 kPa at 2 kPa and below; the rate of heating and cooling, computed every 5 min, whose average shall not exceed 1 degree C per minute, or else the fastest heating and cooling times shall be specified; the rate of change of air pressure, not more than 10 kPa per minute; and the air speed, not more than 1 m/s or adjustable.

Three notes are attached to the table: in a low temperature with low pressure test, if the pressure is below 10 kPa, and in a high temperature with low pressure test, if the pressure is below 4 kPa, the temperature deviation may be relaxed as appropriate; the manufacturer shall state the fastest heating and cooling times in the technical documentation of the product; and the manufacturer shall state in the same documentation the range over which the air speed can be adjusted.

5.2 Requirements on 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 resists heat, is not readily oxidised or corroded, and has a certain mechanical strength.

5.2.2 The insulating material shall withstand both high and low temperature and shall be flame retardant.

5.2.3 The thickness of the insulating layer shall be such that the temperature of the outer surface of the chamber does not exceed 50 degrees C, and such that when the chamber is operated at an ambient temperature of 15 degrees C to 35 degrees C and a relative humidity below 85 % no visible condensation appears.

5.2.4 The heating and refrigerating components shall not radiate directly onto the specimen.

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

5.2.6 The auxiliary devices of the chamber and the materials of its inner wall shall not contaminate the air inside the chamber.

5.2.7 The sealing strip of the chamber door shall not harden and lose its sealing property at low temperature.

5.2.8 The pipework of the refrigerating system shall be tightly and reliably sealed and shall not leak gas, water or oil.

5.2.9 A device for the connection of test leads shall be provided.

5.2.10 The painted or plated finish shall be smooth and even in colour, and shall show no bare patches, peeling, blistering or scratches.

5.2.11 A rack for placing or hanging the specimens shall be provided.

5.3 Safety and environmental protection requirements

5.3.1 The insulation resistance between the terminals and the metal casing of the chamber shall be above 2 Mohm in the cold state and above 1 Mohm in the hot state, measured with a 500 V megohmmeter of accuracy class 1.0, and the equipment shall withstand a dielectric strength test at 1 500 V alternating voltage at 50 Hz applied for 5 s.

5.3.2 The protective earthing terminal shall be well connected electrically to the casing of the chamber, shall allow a firm and convenient connection to be made, and shall comply with 7.1.9 of GB/T 14048.1-2000.

5.3.3 Protection and alarm devices against over-temperature, over-current and loss of water shall be provided.

5.3.4 The noise of the complete machine shall not exceed 85 dB(A).

6.1 Main measuring 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 other similar temperature sensors and meeting the following requirements: a sensor time constant of 20 s to 40 s, and an expanded uncertainty of the measuring system (k = 2) not greater than 0.4 degrees C.

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

6.1.4 Air pressure measuring instrument: a pressure gauge whose expanded uncertainty does not exceed 1/3 of the permitted deviation of the pressure being measured.

6.2 Test conditions

6.2.1 The test conditions shall meet the requirements of 4.1, 4.2 and 4.3.

6.2.2 The test shall be carried out with the chamber empty.

6.3 Method for testing the temperature

6.3.1.1 Three horizontal measuring planes, referred to as the upper, middle and lower layers, are defined within the working chamber. The upper layer is at a distance from the ceiling of the working chamber equal to 1/10 of its height, the middle layer passes through the geometrical centre of the working chamber, and 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 as the imaginary plane through the line of intersection of the sloping roof and the vertical face.

6.3.1.2 The measuring points lie on those three planes. The central measuring point is at the geometrical centre of the working chamber, and the distance of each of the remaining measuring points from the wall of the working chamber is 1/10 of the corresponding side length (Figure 1); for a chamber whose working volume does not exceed 1 cubic metre, however, that distance shall not be less than 50 mm.

6.3.1.3 The number of measuring points depends on the size of the working chamber: a) when the volume of the working chamber does not exceed 2 cubic metres there are 9 temperature measuring points, arranged as shown in Figure 1; b) when the volume of the working chamber exceeds 2 cubic metres there are 15 temperature measuring points, arranged as shown in Figure 2.

6.3.2 This test is carried out with the chamber empty and at normal atmospheric pressure.

6.3.3.1 Within the adjustable range of the chamber, the lowest and the highest nominal temperatures are chosen as the test temperatures.

6.3.3.2 Once the temperature at the central measuring point of the working space has first reached the test temperature and has been stable for 2 h, the temperature at every measuring point is measured once each minute, for a total of 30 measurements within 30 min.

6.3.4 The data are then processed as follows: the temperature value of each measuring point is corrected by the correction value of the measuring instrument; doubtful data are discarded, referring to Annex A; formula (1) gives the mean of the 30 values measured at each point during the period of temperature stability; formula (2) gives the temperature gradient as the difference between the greatest and the smallest of those means; formula (3) gives the temperature fluctuation as the difference between the highest and the lowest temperature at the point concerned; and formula (4) gives the temperature deviation as the difference between the mean at each point and the mean at the centre of the working space.

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 16 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 - General rules (eqv IEC 60947-1:1999) · JB/T 9512-1999 Climatic environmental testing equipment and test chambers - Determination of the sound power level of noise · JJF 1059-1999 Evaluation and expression of uncertainty in measurement

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