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JB/T 10371-2002 Hydraulic unloading relief valve

Basic Information

Standard ID: JB/T 10371-2002

Standard Name: Hydraulic unloading relief valve

Chinese Name: 液压卸荷溢流阀

Standard category:Machinery Industry Standard (JB)

state:in force

Date of Release2002-12-27

Date of Implementation:2003-04-01

standard classification number

Standard ICS number:23.100.30

Standard Classification Number:Machinery>>General Parts>>J20 Hydraulic and Pneumatic Devices

associated standards

Publication information

publishing house:Mechanical Industry Press

other information

drafter:Shen Guangeng, Sun Jianxin, Zhao Manlin, Zhang Qianlong, Lin Dong, Wu Zhendong

Drafting unit:Shanghai Hydraulic and Pneumatic Corporation

Focal point unit:National Hydraulic and Pneumatic Standardization Technical Committee

Proposing unit:China Machinery Industry Federation

Publishing department:State Economic and Trade Commission of the People's Republic of China

Introduction to standards:

This standard specifies the basic parameters, technical requirements, test methods, inspection rules and marking, packaging, transportation and storage requirements of hydraulic unloading relief valves. JB/T 10371-2002 Hydraulic unloading relief valves JB/T10371-2002 Standard download decompression password: www.bzxz.net

Some standard content:

ICS23.100.30
Machinery Industry Standard of the People's Republic of China
JB/T 10371--2002
Hydraulic fluid power unloading relief valve
Hydraulic fluid power unloading relief valve2002-12-27Promulgated
2003-04-01Implementation
Promulgated by the State Economic and Trade Commission of the People's Republic of ChinaForeword
1 Scope
2 Normative references
3 Terms and definitions
4 Quantity, symbol and unit
5 Marking and basic parameters
5.1 Marking ...
Basic parameters
6 Technical requirements.
General requirements,
Performance requirements
Assembly requirements
Appearance requirements
Performance test methods
Test equipment
Test conditions
Test items and test methods
8 Assembly and appearance inspection methods
Inspection rules,
Inspection classification
Judgment rules
Marking, packaging, transportation and storage
Appendix A (Normative Appendix) Test circuit and characteristic curve A.1
Test circuit
A.2 Characteristic curve
Principle diagram of test circuit
Working oil port (A port) set pressure--working oil port (A port) pressure change rate curveWorking oil port (A port) set pressure--unloading pressure curveFigure A.3
Figure A.4 Flow-
-unloading pressure curvebzxZ.net
Figure A.5 Working oil port (A port) set pressure--repeat accuracy error curve.Figure A.6 Flow-working oil port (A port) check valve pressure loss curve..Figure A.7
Inlet pressure-internal leakage curve.
Pressure holding time-working oil port (A port) pressure drop characteristic curve Figure A.9 Pressure-regulating torque characteristic curve
Test system block diagram
Automatic pressure rise-unloading characteristic curve
Working oil port (A port) load step-working oil port (P port) pressure response characteristic curve Figure A.12
JB/T 10371--2002
JB/T 10371--2002
Quantity, symbol and unit
Internal cleanliness index,
Allowable variation range of average displayed value of controlled parameter Table 4
Allowable systematic error of measuring system
Factory test items and test methods
Type test items and test methods
Assembly and appearance inspection methods
Appendix A of this standard is a normative appendix.
This standard is proposed by China Machinery Industry Federation. Foreword
This standard is under the jurisdiction of the National Hydraulic and Pneumatic Standardization Technical Committee. JB/T10371—2002
The responsible drafting units of this standard are: Shanghai Hydraulic and Pneumatic General Company, Beijing Machinery Industry Automation Research Institute, Dalian Modular Machine Tool Research Institute Hydraulic Technology Engineering Company.
The participating drafting units of this standard are: Shanghai Yeer Hydraulic Parts Manufacturing Co., Ltd. The main drafters of this standard are: Shen Guangeng, Sun Jianxin, Zhao Manlin, Zhang Qianlong, Lin Guang, Wu Zhendong. This standard is published for the first time.
1 Scope
Hydraulic unloading relief valve
JB/T10371—2002
This standard specifies the basic parameters, technical requirements, test methods, inspection rules and markings, packaging, transportation and storage requirements of hydraulic unloading relief valves (hereinafter referred to as unloading relief valves). This standard applies to unloading relief valves with threaded connections, plate connections and superimposed connections that use hydraulic oil or other liquids with equivalent performance as the working medium.
2 Normative references
The clauses in the following documents become the clauses of this standard through reference in this standard. For all dated referenced documents, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties that reach an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For all undated referenced documents, the latest versions are applicable to this standard. GB/T 786.1 Hydraulic and pneumatic graphic symbols (GB/T 786.1-1993, eqvISO 1219-1:1991, Fluid power systems and components—Graphic symbols and circuit diagrams-Part I:Graphic symbois ) GB/T2346 Hydraulic and pneumatic systems and components nominal pressure series GB/T2828 Batch inspection counting sampling procedures and sampling tables (applicable to continuous batch inspection) GB/T2878 Hydraulic component threaded connection oil port types and sizes General technical conditions for hydraulic components
GB/T7935
GB/T8099 Hydraulic stack valve mounting surface
Hydraulic relief valve mounting surface (GB/T8101-2002, ISO6264:1998, Hydraulicfluidpower GB/T 8101
pressure-relief valves-mounting suefaces, MOD) GB/T14039--2002 Hydraulic transmission oil solid particle contamination level code (ISO4406: 1999, MOD) GB/T17446 Fluid transmission system and component terminology (GB/T17446-1998, idt ISO5598: 1985) GB/T 17489
Hydraulic particle contamination analysis Extraction of liquid sample from working system pipeline (GB/T17489-1998, idt ISO4021: 1992)
JB/T 7858
Hydraulic component cleanliness assessment method and hydraulic component cleanliness index 3 Terms and definitions
The terms and definitions established in GB/T17446 and the following terms and definitions apply to this standard. 3.1
Nominal flow
The nominal flow of the unloading relief valve. 3.2
Test flow test flow
The flow specified when testing the performance of the test valve. 4 Quantities, symbols and units
Quantities, symbols and units are shown in Table 1.
JB/T 10371—2002
Nominal diameter of valve
Volume flow
Inner diameter of pipe
Pressure, differential pressure
Mass density of oil
Kinematic viscosity
Volume elastic modulus
Note: M—-Mass: L
5 Marking and basic parameters
5.1 Marking
Table 1 Quantities, symbols and units
p, ap
Length: T-
One time;?,
Temperature.
ML-IT-2
ML-r-2
Pa(MPa)
s(min)
A clear and permanent mark/nameplate should be made at an appropriate and obvious position on the product. The content of the mark/nameplate should comply with the provisions of GB/T7935, and the graphic symbols used should comply with the provisions of GB/T786.1. 5.2 Basic parameters
The basic parameters of the unloading relief valve should include: nominal pressure, nominal flow, nominal diameter, rated flow, and pressure adjustment range. 6 Technical requirements
General requirements
6.1.1 The nominal pressure should comply with the provisions of GB/T2346, and 6.1.2 The plate connection mounting surface should comply with the provisions of GB/T8101. 6.1.3 The type and size of the threaded oil port should comply with the provisions of GB/T2878. 6.1.4 Other technical requirements should comply with the provisions of GB/T7935. 6.1.5 The manufacturer shall specify the applicable conditions and environmental requirements of the product in the product samples and related materials. 6.2 Performance requirements
The performance requirements of the unloading relief valve shall include
Working oil port (A port) pressure change rate:
Repeat accuracy error;
Release pressure:
Working oil port (A port) one-way valve pressure loss: d)
Internal leakage:
Pressure retention:
Adjusting torque:
Transient characteristics:
Sealing: Under rated working conditions, the static seal of the unloading relief valve shall not leak, and the dynamic seal shall not drip oil: Pressure resistance: Each pressure-bearing oil port of the unloading relief valve shall be able to withstand 1 of the maximum working pressure of the oil port.5 times, there shall be no external leakage and parts damage;
JB/T 10371—2002
k) Durability: Under rated working conditions, the unloading relief valve shall be able to withstand the specified number of actions, its parts shall not have abnormal wear and other forms of damage, and the decline of various performance indicators shall not exceed 10% of the specified value. 6.3 Assembly requirements
6.3.1 The assembly of the unloading relief valve shall comply with the provisions of GB/T7935. 6.3.2 The internal cleanliness of the unloading relief valve shall comply with the provisions of Table 2. Table 2 Internal cleanliness index
Nominal diameter mm
6.4 Appearance requirements
The appearance of the unloading relief valve shall comply with the provisions of GB/T7935. 7 Performance test method
7.1 Test device
7.1.1 The test shall have a test bench that complies with the test circuit shown in Figure A.1 in Appendix A. 7.1.2 Flow and pressure of oil source:
The flow of oil source should be adjustable and should be greater than the test flow of the valve under test. The pressure of the oil source should be able to exceed the nominal pressure of the valve under test by 20% to 30% for a short time. Cleanliness index value
7.1.3 It is allowed to add components to the given basic circuit to adjust the pressure, flow or ensure the safe operation of the test system, but it should not affect the performance of the valve under test.
7.1.4 The inner diameter of the pipe and pipe joint connected to the valve under test should be consistent with the actual diameter of the valve under test. 7.1.5 Position of pressure measuring point:
7.1.5.1 The inlet pressure measuring point should be set between the downstream of the disturbance source (such as valve, elbow, etc.) and the upstream of the valve under test. The distance from the disturbance source should be no less than 10d (d is the inner diameter of the pipe). The distance from the valve under test should be no less than 5d. 7.1.5.2 The outlet pressure measuring point shall be set at least 10d downstream of the test valve. 7.1.5.3 When testing according to Class C accuracy, the position of the pressure measuring point is allowed to be inconsistent with the above requirements, but the corresponding correction value shall be given. 7.1.6 Pressure measuring hole:
The diameter of the pressure measuring hole shall be no less than 1mm and no more than 6mm. 7.1.6.11
The length of the pressure measuring hole shall be no less than 2 times the true diameter of the pressure measuring hole. The axis of the pressure measuring hole is perpendicular to the axis of the pipeline. The intersection of the inner surface of the pipeline and the pressure measuring hole shall maintain a sharp edge and shall not have burrs. 7.1.6.3
The inner diameter of the connecting pipe between the pressure measuring point and the measuring instrument shall be no less than 3mm. 7.1.6.4
When the pressure measuring point is connected to the test instrument, the air in the connecting pipe shall be removed. 7.1.6.5
The temperature measuring point shall be set at no more than 15d upstream of the inlet pressure measuring point of the test valve. 7.1.7
7.1.8 Oil sampling points Oil sampling points and extraction samples should be set in the test circuit in accordance with the provisions of GB/T17489. 7.2 Test conditions
7.2.1 Test medium
The test medium is general hydraulic oil.
Temperature of test medium: Unless otherwise specified, type tests should be carried out at 50℃±2℃, and factory tests should be carried out at 50℃±4℃7.2.1.2
.
7.2.1.3 Viscosity of test medium: The kinematic viscosity at 40℃ is 42mm2/s~74mm2/s (special requirements shall be specified separately). 7.2.1.4 Cleanliness of test medium: The solid particle contamination level of the test system oil should not be higher than the level specified in GB/T14039--2002-/19/16.
JB/T 10371—2002
7.2.2 Steady-state conditions
When the variation range of the average displayed value of the controlled parameter complies with the provisions of Table 3, it is a steady-state condition. The measured values ​​of the test parameters should be recorded under the steady-state condition.
Table 3 Permissible variation range of the average displayed value of the controlled parameter Measurement parameter
Note: For the measurement accuracy level, see 7.2.5.
7.2.3 Transient conditions
Permissible variation range of the average displayed value of the controlled parameter corresponding to each measurement accuracy level A
7.2.3.1 The apparent volumetric stiffness of the oil chamber composed of the test valve and the relevant parts of the test circuit should ensure that when the accumulator 11 and the throttle valve 6 in the test circuit are closed, the change rate of the inlet pressure of the test valve is within the range of 600MPa/s to 800MPa/s. Note: The inlet pressure change rate refers to the ratio of the pressure change from 10% to 90% of the difference between the final steady-state pressure value and the initial steady-state pressure value to the corresponding time.
7.2.3.2 The relative position between the step loading valve and the test valve can be determined by controlling the pressure gradient between them to limit the influence of the oil compressibility. The pressure gradient between them can be calculated. The calculated pressure gradient should be at least 10 times the measured inlet pressure gradient of the test valve. Pressure gradient calculation formula:
Where:
dp_9vsKs
qvs---Steady-state flow rate set for the test valve 4: Ks
-Equivalent bulk elastic modulus of the oil:
V--The oil circuit connection volume between the test valve 4 and the step loading valve (hydraulic control check valve 7) in the test circuit. 7.2.3.3 The action time of the step loading valve in the test circuit shall not exceed 10% of the response time of the test valve 4, and shall not exceed 10ms at most. 7.2.4 Test flow rate
7.2.4.1 When the specified rated flow rate of the test valve is less than or equal to 200L/min, the test flow rate shall be the rated flow rate. 7.2.4.2 When the specified rated flow rate of the test valve is greater than 200L/min, the test flow rate shall be allowed to be 200L/min, but it shall be subject to working condition assessment, and the performance index of the test valve shall be based on meeting the working condition requirements. 7.2.4.3 The factory test is allowed to be carried out at a reduced flow rate, but the corresponding correction value shall be given to the performance index. 7.2.5 Measurement accuracy level
The measurement accuracy level is divided into three levels: A, B, and C. The type test shall not be lower than level B, and the factory test shall not be lower than level C. The allowable system error of the measurement system corresponding to each level shall comply with the provisions of Table 4. Table 4 Allowable system error of measurement system
Measurement parameters
Pressure (gauge pressure p<0.2MPa)
Pressure (gauge pressure p≥0.2MPa)
(%)
Allowable error B of measurement system corresponding to each measurement accuracy grade
7.3 Test items and test methods
7.3.1 Factory test
The factory test items and test methods of unloading relief valve shall be in accordance with the provisions of Table 5. Table 5 Factory test items and test methods
Test items
Pressure resistance
Pressure regulation-unloading characteristics
Repeat accuracy error
Working oil port (port A)
Pressure loss of check valve
Internal leakage
Test method
Overflow port connected to oil tank
Apply 1.5 times the maximum working pressure of the oil port to each pressure-bearing port at a rate of 2% per second, and maintain the pressure for 5 minutes.
The volume of the accumulator 10 can be (1.6~6.3) Select within the range of L, and its inflation pressure shall not be equal to or greater than the lower limit of the pressure regulating range of the test valve 4. Adjust the relief valve 2 so that the system pressure is 115% of the upper limit of the pressure regulating range of the test valve 4 (it only acts as a safety valve), and the flow through the test valve 4 is the test flow. Carry out the following tests respectively:
① Adjust the throttle valve 6 to an appropriate opening, and at the same time adjust the pressure regulating hand wheel of the test valve 4 from full looseness to gradual tightening, observe the pressure rise through the pressure gauge 3-3, and measure the pressure regulating range, and repeat the test for no less than 3 times. ② Adjust the throttle valve 6 to an appropriate opening, and adjust the test valve 4 to the lower limit and upper limit of the pressure regulating range respectively, so that the test valve 4 automatically unloads and increases the pressure, and at the stable moment, use the pressure gauge 3-3 to measure the pressure pAL when the accumulator 10 is about to be charged. The difference between this pressure and the set pressure pAH is the percentage of the set pressure pA, which is the pressure change rate of the A oil port of the test valve 4. Repeat the test for no less than 3 times.
ApA - PAH =PAlL ×100%
③ During test ②, when the hydraulic pump 1 is unloaded, immediately close the throttle valve 6 and measure the pressure with pressure gauges 3-1 and 3-2. The pressure difference is the unloading pressure of the test valve 4.
According to the test method of No. 2②, when testing the pressure change rate of the working oil port (port A) of the test valve 4 at the upper limit of the pressure regulation range, find the highest upper pressure pab, the lowest upper pressure PAHrnin, the highest lower pressure PALmax and the lowest lower pressure PALmin according to the upper pressure pAH (i.e., the set pressure) and the lower pressure pAL (i.e., the pressure when charging the accumulator 10) measured each time, and then calculate the repeatability error E of the pressure change rate of the working oil port (port A) of the test valve 4 according to the following formula:
E=(PAHmax -PALnin)-(PAHinix - PALman)×100%
Fully open the throttle valve 6 and make the flow through the test valve 4 the test flow. Use pressure gauges 3-1 and 3-3 to measure the pressure, and the pressure difference is the pressure loss of the one-way valve of the working oil port (port A) of the test valve 4. Close the stop valves 11-1, 11-2 and the throttle valve 6, adjust the relief valve 2 and the test valve 4, so that the test valve 4 reaches the upper limit of the pressure regulating range, and the flow through the test valve 4 is the test flow.
Adjust the overflow valve 2 to make the system pressure drop to 75% of the upper limit of the pressure regulating range of the test valve 4. After 30s, measure the internal leakage at the overflow port of the test valve 4. JB/T 10371—2002
Test type
JB/T 10371——2002
Test items
Pressure retention
Sealing
7.3.2 Type test
Wrap 5 (continued)
Test method
When conducting this test, the volume of the accumulator 10 is specified to be 0.63L, and its charging pressure should be less than the lower limit of the pressure regulating range of the test valve 4. Completely close the throttle valve 6 (during the entire test process, no oil should pass through the throttle valve). Adjust the relief valve 2 and the test valve 4 so that the pressure at the working oil port (port A) of the test valve 4 is slightly higher than the upper limit of the pressure regulating range. Then, open the stop valve 11-1. When the indicated pressure of the pressure gauge 3-3 drops to the upper limit of the pressure regulating range of the test valve 4, start recording the time and measure the drop value of the indicated pressure of the pressure gauge 3-3 within a 5-minute time interval.
① Place a clean white paper under the adjusting screw of the test valve 4 (it is allowed to put the white paper in a container). During the whole test, there should be no oil drops on the white paper. ② After the test, press clean absorbent paper on each static seal. There should be no oil stains.
Type test items and test methods shall be in accordance with the provisions of Table 6. Table 6 Type test items and test methods
Test items
Steady-state characteristics
Test method
Test type
Test all items as specified in the factory test items and test methods: ① In the working oil port (A port) pressure change rate test, the working oil port (A port) pressure pAH of the test valve 4 should be gradually increased from the lower limit of the pressure regulation range to the upper limit. During this period, several measuring points are set (the set measuring points should be sufficient to draw a curve), and the pressure pAL when the accumulator 10 is about to be charged is measured point by point, and the working oil port (A port) pressure change rate - APA is calculated. Draw
the curve of the set pressure of the working oil port (port A) of the tested valve 4 and the pressure change rate of the working oil port (port A) (see Figure A.2)
② During the unloading pressure test, the following tests should be carried out respectively: A. Constant flow test
Let the flow through the tested valve 4 be the test flow, and the pressure PA of the working oil port (port A) of the tested valve 4 gradually increase from the lower limit of the pressure regulation range to the upper limit, during which several measuring points are set (the set measuring points should be sufficient to draw the curve), and the unloading pressure Apo of the tested valve 4 is measured point by point. Draw the curve of the set pressure of the working oil port (port A) of the tested valve 4 and the unloading pressure (see Figure A.3). B. Constant pressure test
Adjust the working oil port (port A) pressure of the test valve 4 to the lower limit and upper limit of the pressure regulation range, respectively increase the flow q through the test valve 4 from zero to the test flow, set several measuring points (the set measuring points should be sufficient to draw a curve), measure the unloading pressure APo of the test valve 4 point by point, and draw the flow-unloading pressure curve of the test valve 4 (see Figure A.4). ③ During the repeatability error test, adjust the working oil port (port A) pressure pAH of the test valve 4 to gradually increase from the lower limit of the pressure regulation range to the upper limit, set several measuring points (the set measuring points should be sufficient to draw a curve), and measure the repeatability error E of the test valve 4 point by point. Draw the set pressure-repeatability error curve of the working oil port (port A) of the test valve 4 (see Figure A.5). ③ During the pressure loss test of the working oil port (port A) check valve, the flow rate qv through the working oil port (port A) of the test valve 4 is gradually increased from zero to the test flow rate, and several measuring points are set during this period (the set measuring points should be sufficient to draw a curve), and the pressure loss △p of the working oil port (port A) check valve of the test valve 4 is measured point by point. Draw the flow rate of the test valve 4-the pressure loss curve of the working oil port (port A) check valve (see Figure A.6)
③ During the internal leakage test, the inlet pressure of the test valve 4 is gradually reduced from 75% of the upper limit of the pressure regulation range to zero, and several measuring points are set during this period (the set measuring points should be sufficient to draw a curve), and the internal leakage of the overflow port of the test valve is measured point by point. Draw the pressure-internal leakage full disk curve of the test valve 4 (see Figure A.7)
③ During the pressure holding performance test, the pressure of the working oil port (port A) of the test valve 4 should be tested under the lower limit and upper limit of the pressure regulation range. The pressure holding time should be no less than 15 minutes. During this period, several measuring points should be set (the set measuring points should be sufficient to draw the curve), and the pressure drop value △p of the working oil port (port A) of the test valve 4 should be measured point by point. Draw the pressure drop characteristic curve of the working oil port (A port) of the test valve 4 during the holding time (see Figure A.8)
Test items
Regulating torque
Transient characteristics
Durability
Table 6 (continued)
Test method
JB/T 10371—2002
Regulate the relief valve 2 so that the system pressure is 115% of the upper limit of the pressure regulating range of the test valve 4 (it only acts as a safety valve), and the flow through the test valve 4 is the test flow. Then adjust the test valve 4 so that the inlet pressure changes from the lower limit of the pressure regulating range to the upper limit, and then from the upper limit to the lower limit. During this period, several measuring points are set (the set measuring points should be sufficient to draw a curve), and the regulating torque of the test valve 4 during the adjustment process is measured. And draw the pressure-regulating torque characteristic curve of the test valve 4 during the adjustment process (see Figure A.9). When conducting this test, the volume of the accumulator 10 is specified to be 0.63L, and its charging pressure shall not be equal to or greater than the lower limit of the pressure regulating range of the test valve 4. The test system is shown in block diagram A.10. The test method is as follows:
Adjust the relief valve 2 so that the system pressure is 130% of the upper limit of the pressure regulating range of the test valve 4 (it only acts as a safety valve), and the flow through the test valve 4 is the test flow. The following tests are carried out respectively:
① Boost-unload characteristic test:
Adjust the throttle valve 6 so that the test valve 4 is boosted and unloaded at a frequency of (1/6~1/3)Hz. The pressure change process of the working oil port (P port) and the working oil port (A port) of the test valve 4 is recorded by a recorder through the pressure sensors 3-1 and 3-2, and the boost time, unloading time and charging time of the working oil port (A port) of the test valve 4 are obtained (see Figure A.11). ② Working oil port (A port) load step - working oil port (P port) pressure response characteristic test: close the throttle valve 6, and supply pressure to the control oil circuit, open the hydraulic control check valve 7 in reverse, and put the test valve in the unloading state. Then suddenly unload the control oil circuit, quickly close the hydraulic control check valve 7, and use the pressure sensors 3-1 and 3-2 to record the pressure change process of the working oil port (P port) and the working oil port (A port) of the test valve 4 with a recorder, and obtain the working oil port (P port) pressure response time and pressure overshoot rate (see Figure A.12).
Adjust the test valve 4 to the upper limit of the pressure adjustment range, and make the flow through the test valve 4 the test flow. Adjust the throttle valve 6 so that the P oil port of the test valve 4 automatically increases pressure and unloads at a frequency of (1/3~2/3) Hz. During the test, record the number of actions of the test valve 4. After reaching the number of actions specified by the durability index, check the main parts and performance of the test valve 4. Assembly and appearance inspection methods
The assembly and appearance inspection methods of the unloading relief valve shall comply with the provisions of Table 7. Table 7 Assembly and appearance inspection methods
Inspection rules
Inspection classification
Test items
Assembly quality
Internal cleanliness
Appearance quality
Product inspection is divided into factory inspection and type inspection. 9.1.1 Factory inspection
Test methods
Visual inspection method.
According to the provisions of JB/T7858.
Self-test method.
Factory inspection refers to the various inspections that should be carried out before the product is delivered. Test type
The items and methods of performance inspection shall comply with the provisions of 7.3.1, and the performance requirements shall comply with the provisions of 6.2. The inspection methods of assembly and appearance shall comply with the provisions of Chapter 8, and the quality shall comply with the requirements of 6.3 and 6.4. 9.1.2 Type inspection
JB/T 10371-2002
Type inspection refers to the comprehensive assessment of product quality, that is, comprehensive inspection according to the technical requirements specified in the standard. Type inspection shall be carried out in any of the following cases:
a) Trial production and identification of new products or old products transferred to the factory for production: after formal production, if there are major changes in structure, materials, and processes, which may affect product performance; b)
c) When the product is resumed after a long period of suspension; d) When there is a significant difference between the factory inspection result and the last type inspection result; e) When the national quality supervision agency proposes a type inspection requirement. The items and methods of performance inspection shall be in accordance with the provisions of 7.3.2, and the performance requirements shall comply with the provisions of 6.2: The inspection methods for assembly and appearance shall be in accordance with the provisions of Chapter 8, and the quality shall comply with the requirements of 6.3 and 6.4. 9.2 Sampling
The sampling plan for product inspection shall be in accordance with the provisions of GB/T2828. Note: Sampling for quality supervision inspection shall be in accordance with relevant regulations. 9.2.1 Sampling for factory inspection
a) Qualified quality level (AQL value): 2.5; b) Sampling plan type: normal inspection one-time sampling plan; c) Inspection level: general inspection level II; The sample size for pressure resistance test is 0.3%, but shall not be less than two units. 9.2.2 Sampling for type inspection
a) Qualified quality level (AQL value): 2.5 [6.5]; b) Sampling plan type: normal inspection one-time sampling plan: Sample size: 5 units [2 units]
Note: The values ​​in square brackets are only applicable to durability tests. 9.2.3 Sampling for internal cleanliness inspection
a) Qualified quality level (AQL value): 2.5; b) Sampling plan type: normal inspection one-time sampling plan; c) Inspection level: special inspection level S-2. 9.3 Judgment rules
According to GB/T2828.
10 Marking, packaging, transportation and storage
Marking, packaging, transportation and storage shall comply with the provisions of GB/T7935. Special requirements may be stipulated separately.
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