Some standard content:
Machinery Industry Standard of the People's Republic of China
JB/T7696.1~7696.4-95
Instruments for Engineering Machinery
Published on 1995-06-20
Ministry of Machinery Industry of the People's Republic of China
Implementation on 1996-01-01
Mechanical Industry Standard of the People's Republic of China
Pressure Gauges for Engineering Machinery
Subject Content and Scope of Application
This standard specifies the technical requirements, test methods, inspection rules, etc. for pressure gauges for engineering machinery. JB/T 7696.1-95
This standard applies to pressure gauges for hydraulic systems, lubrication systems and brake systems of engineering machinery. Pressure gauges for other motor vehicles can also be implemented as a reference.
2 Reference standards
GB2828
ZBT35001
Count sampling procedure and sampling table for batch inspection (applicable to inspection of continuous batches) Basic environmental test procedures for electrical and electronic products Test Db: Alternating damp heat test method Protection level of low-voltage electrical enclosure
Basic technical conditions for automotive electrical equipment
3 Structural types and categories
Pressure gauges are generally composed of indicators and sensors. Their structural types and types are shown in Table 1. Table 1
Electrical type
Mechanical type
4 Technical requirements
4.1 Basic parameters
Indicator
Electromagnetic type
Bimetallic type
Spring tube type
Diaphragm type
Pressure gauges shall comply with the requirements of this standard and shall be manufactured in accordance with the drawings and design documents approved through the prescribed procedures. 4.2 Units and divisions
Sensor
Variable resistance type
Bimetallic type
The measurement unit of pressure gauges is generally expressed in MPa, and in principle there are no less than two divisions: lower limit value-middle value-upper limit value. It can also be indicated by regional color code, with no less than two color code areas. 4.3 Standard environment
Relative humidity
18~28℃
45%~75%
86~106kPa
4.4 Working environment temperature
The working environment temperature of the pressure gauge is shown in Table 2.
Approved by the Ministry of Machinery Industry on June 20, 1995
Implemented on January 1, 1996
4.5 Appearance
Indicator
Sensor
JB/T 7696.195
Set temperature
-40～+70
40~+100
4.5.1 The protective layer should be uniform, without obvious defects such as bubbles, spots, rust and shedding. 4.5.2 Glass and other transparent materials should not have scratches and refraction that affect accurate readings. 4.5.3 The graduation lines, symbols, numbers and other signs on the dial must be clear and complete. 4.5.4 The exposed part of the pressure gauge indicator should not have a strong glaring luster. Working temperature
20~+55
28~+100
4.5.5 When the electric pressure gauge is not working, the pointer of its indicator should be below the zero graduation line and can touch the zero graduation line; when the machine-type pressure gauge is not working, its pointer should stop at the stopper and press the equal graduation line without leaving. 4.6 Paint layer and plating
4.6.1 In addition to complying with the provisions of Article 4.5.1 of this standard, the paint layer should have a bright surface color, a solid bond with the surface of the covering, and no shrinkage or delamination after the temperature resistance test. 4.6.2 The electroplating layer and chemical treatment layer shall comply with the relevant provisions of ZBT35001. 4.7 Performance
4.7.1 Compatibility
The electrical pressure gauge indicator shall be used in conjunction with the pressure gauge sensor designed to match it, and the manufacturer shall ensure its interchangeability. 4.7.2 Movable part movement state
When the pressure changes steadily, the pointer of the pressure gauge indicator shall move steadily, and there shall be no obvious jumping or jamming. 4.7.3 Basic error
At ambient temperature, the basic error of the pressure gauge is as follows: The basic error of the middle pressure value of the electrical pressure gauge scale is ±8% of the upper pressure value, and the basic error of the upper pressure value of the scale is 12% of the upper pressure value.
The basic errors of the middle pressure value and the upper pressure value of the mechanical pressure gauge scale are both ±4% of the upper pressure value of the scale. 4.7.4 Pointer response time
When the pressure drops sharply from the upper limit of the scale to zero, the pointer must return to less than 10% of the upper limit within 2 minutes. When the pressure is zero, the pointer should not leave the zero graduation line. 4.7.5 Overload
Electrical pressure gauges should withstand an overload test of 1.5 times the upper limit of the scale, and mechanical pressure gauges should be able to withstand an overload test of 1.2 times the upper limit of the scale. After the test, their performance should comply with the provisions of Articles 4.7.2 and 4.7.3 of this standard. 4.7.6 Voltage resistance
The indicator of the electrical pressure gauge should be able to withstand a voltage of 50Hz, an actual sinusoidal waveform of 550V, and a test lasting 1 minute. Its insulation should not be broken down. In large-scale continuous production, it is allowed to use a test with a voltage of 660V and a duration of 1s instead. 4.7.7 Temperature resistance performance
When the pressure gauge is subjected to a temperature impact test according to the working environment temperature range, the absolute value of the change in its indicated value caused by this should not exceed the following provisions:
10% of the upper pressure value of the scale for an electrical pressure gauge; bZxz.net
4.7.8 Humidity and heat resistance
The pressure gauge should be able to withstand an alternating humidity and heat test with a high temperature of 40°C and a cycle of 6 days. After the test, it should be able to meet the requirements of 4.7.2 and 2
4.7.3 of this standard.
JB/T7696.195
4.7.9 Voltage influence
When the electric pressure gauge is subjected to voltage test according to the voltage fluctuation range specified in Table 3, the absolute value of the change in the indicated value shall not exceed 10% of the upper limit pressure value of the scale.
Nominal voltage
Vibration resistance
Test voltage
Voltage fluctuation range
The pressure gauge shall be able to withstand the fixed and swept vibration tests in the three directions of up and down, left and right, and front and back. The test specifications shall comply with the provisions of Table 4, Table 5 and Table 6.
First, obtain the common grip point according to the provisions of Table 4,
Resonance rate
4. 7. 10. 2
Sweep frequency period
Resonance acceleration
If there is no resonance point, conduct the vibration endurance test according to the provisions of Table 5. Table 5
Vibration rate
Vibration acceleration
Test time h
Full vibration shed
0.4 effect
4.7.10.3 When there is a resonance point, the vibration test should be carried out for 1 hour up and down, 0.5 hours left and right, and front and back according to the resonance point and the full amplitude shown in Figure 1. Then do the test specified in Table 6,
16. 7 -33. 3 65. 7 156. 7 333. 4 666. 8 Loss rate Hz
Vibration rate
Vibration acceleration
JB/T7696.1-95
Test time h
After the vibration test, the parts of the pressure gauge should not be loose or damaged, and the absolute value of the change in the indicated value shall not exceed 7% of the upper limit pressure value of the scale, and shall comply with the provisions of Article 4.7.2 of this standard. 4.7.11 Durability
The pressure gauge should be able to withstand 30,000 pressure cycle tests. After the test, the change in the indicated value shall not exceed 7% of the upper limit pressure value of the scale, and shall comply with the provisions of Article 4.7.2 of this standard. 4.7.12 Dustproof performance
After the dustproof test, the pressure gauge should not have dust that affects the reading, and shall comply with the provisions of Articles 4.7.2 and 4.7.3 of this standard. 4.7.13 Water resistance
After the water spray test, the inner surface of the glass of the pressure gauge shall not be water-permeable and shall comply with the provisions of Articles 4.7.6 and 4.7.3 of this standard. 5 Test method
5.1 Appearance inspection
During the appearance inspection, the visual inspection method shall be used under 3001x uniform illumination and an eye distance of 500mm. 5.2 Inspection of paint layer and plating
5.2.1 The appearance quality of the subsequent layer shall be inspected by visual inspection. 5.2.2 The adhesion of the paint layer shall be inspected by the grid method on the surface of the fully dried paint layer, that is, four vertical and horizontal lines shall be drawn with a No. 11 or No. 12 medical surgical blade, with a spacing of 1mm between each line, to form 9 squares, and observe whether the paint layer in the squares has delamination. 5.2.3 The temperature effect performance of the layer shall be inspected after the temperature effect test in Article 4.7.7. 5.2.4 The alternating humidity and heat performance of the paint layer should be tested after the alternating humidity and heat test in 4.7.8. 5.2.5 The quality of the electroplating layer and the chemical treatment layer shall be inspected in accordance with the method specified in Article 4.12 of ZBT35001. 5.3 Performance test
5.3.1 Test conditions
The pressure gauge indication value shall be inspected under the standard environment specified in Article 4.3 of this standard. 5.3.1.1
5. 3. 1.2
5. 3. 1. 3
The installation position of the pressure gauge on the test bench shall be the same as the actual installation position in the vehicle model. The pressure gauge indicator shall be tested in conjunction with the matching designed sensor. The ripple voltage of the DC regulated power supply used for the test shall not be greater than 10mV, the power supply voltage during the test shall comply with the provisions of Table 7, and the accuracy of the voltmeter shall not be lower than Class 0.5.
Nominal voltage
Test voltage
Durability test voltage
14.0±0.5
28.0±1.0
5.3.1.5. The accuracy of the standard pressure gauge shall not be lower than Class 0.4, and the upper limit pressure value of its scale shall not be greater than 1.5 times the upper limit pressure value of the scale of the pressure gauge being tested.
5.3.1.6 The accuracy of the standard thermometer shall not be lower than ±1°C. 5.3.1.7
Except for the test of changing the indicated value reading and the alarm test, the other test items of the pressure gauge are in the non-working state. 5.3.2 Basic error test
JB/T7696.1-95
The test is carried out by comparing with the standard gauge at the middle pressure value and the upper limit pressure value of the scale of the pressure gauge. During the test, the pressure should be maintained at the upper limit pressure value of the scale for at least 2 minutes (for the electrical pressure gauge, it should be maintained for at least 6 minutes), and then the pressure should be changed steadily in a sequence of first decreasing and then increasing. When the pressure is zero and the power is turned on, the pointer should not leave the scale line after the instrument is powered on. Before reading the indicated value, it should be kept at the tested scale line (pressure value) for at least 2 minutes. Article 4.7.2 of this standard should be tested in this test. 5.3.3 Pointer response time test
First, make the pressure gauge indicate the upper limit pressure value of the scale stably, and then reduce the pressure sharply to zero. When the pointer returns to 10% of the upper limit pressure value, read the pointer response time.
5.3.4 Overload test
For the electrical pressure gauge, a pressure of 1.5 times the upper limit pressure value of the scale should be applied, and for the mechanical pressure gauge, a pressure of 1.2 times the upper limit pressure value of the scale should be applied. The test time is 1 minute. After the test, the pressure gauge shall be placed in the standard environment specified in Article 4.3 of this standard for no less than 4 hours, and then the motion state and indication value of its movable parts shall be checked according to the method specified in Article 5.3.1 of this standard. 5.3.5 Withstand voltage test
The voltage specified in Article 4.7.5 of this standard shall be applied between the indicator circuit system of the pressure gauge whose shell is not grounded and the shell: During the test, the applied voltage shall start from no more than half of the full value of the specified voltage, rise evenly and slowly to the full value, and maintain for 1 minute, and then drop evenly and slowly to zero. The rise and fall time shall not be less than 10$. The test shall be carried out under the standard environment specified in Article 4.3 of this standard, and the capacity of the test transformer shall not be less than 0.5kVA. 5.3.6 Temperature influence test
The test of the electrical pressure gauge shall be carried out only at the middle pressure value of the scale when the pressure rises, and the test of the mechanical pressure gauge shall be carried out at the middle pressure value and the upper pressure value of the scale. 5.3.6.1 Low temperature effect test
First, check the indicated value of the pressure gauge under the standard environment specified in Article 4.3 of this standard, then put the pressure gauge in a low temperature box, cool it down from the standard temperature to -20±3°C with the box, keep it warm for 2 hours, and check its indicated value according to the method specified in Article 5.3.2 of this standard, thereby obtaining the difference between the indicated value under low temperature and standard environment.
5.3.6.2 High temperature effect test
First, check the indicated value of the pressure gauge under the standard environment specified in Article 4.3 of this standard, then put the pressure gauge in a high temperature box, heat it up from the standard temperature to 55±2°C with the box and keep it warm for 2 hours, and check its indicated value according to the method specified in Article 5.3.2 of this standard, thereby obtaining the difference between the indicated value under high temperature and standard environment.
After the low temperature and high temperature tests, place eggs in the pressure gauge under the standard environment for 4 hours, and then check its performance according to the method specified in Article 5.3.2 of this standard. The low temperature and high temperature tests are carried out in the order of low temperature first and high temperature later. 5.3.7 Alternating damp heat test
The test is carried out in accordance with the provisions of GB2423.4. After the test, the pressure gauge is placed in the standard environment specified in Article 4.3 of this standard for 2 hours, and then its performance is checked in accordance with the method specified in Article 5.3.2 of this standard to see if it meets the provisions of Articles 4.7.2 and 4.7.3 of this standard. 5.3.8 Voltage influence test
First, adjust the power supply voltage to the test voltage and check the indication value of the pressure gauge. Then adjust the power supply voltage to low (and high) voltage respectively, and then check its indication value respectively, so as to obtain the difference between the indication value of low and high voltage and the test voltage. The test is only carried out at the middle pressure value of the scale when the pressure rises. 5.3.9 Vibration test
The pressure gauge indicator and pressure gauge sensor are circled on the vibration test bench in the normal working position in turn, and the sweep frequency, fixed frequency and vibration test are carried out in accordance with the provisions of Article 4.7.10 of this standard. The dynamic test of the pressure gauge indicator should be carried out at the middle pressure value of the scale, and the vibration test of the pressure gauge sensor should be carried out in the non-working state. After the test, the pressure gauge shall be placed in a standard environment for 4 hours, and then its performance shall be checked according to the method specified in Article 5.3.2 of this standard. 5
5.3.10 Durability test
JB/T 7696. 195
The pressure gauge shall be installed on the vehicle model, engine or test bench in the normal working position for testing, and the pressure gauge shall be subjected to 2 to 3 cycles of alternating pressure per minute. Each cycle shall make the indicated value of the pressure gauge rise from zero to 60% of the upper limit pressure value of the scale, and then drop to zero, for a total of 30,000 times.
After the test, its performance shall be checked according to the method specified in Article 5.3.2 of this standard. 5.3.11 Dust test
5.3.11.1 This test should be carried out in a closed box with a length, width and height of 900~1200mm. Except for the necessary sample clamping device, there should be no device that prevents dust from flying. The dust should be able to gather near the European air hole. 5.3.11.2 Test conditions are as specified in Table 8. The sample is more than 150mm away from the box wall. 5kg of ordinary Portland cement is injected into the box, and then air is sprayed for 10s every 15min to make the dust diffuse into a uniform state in the box. The test is carried out for 8h. After the test, use visual and hand feeling to check whether there is dust in the pressure gauge. Table 8
Titon Portland Cement 5kg
5.3.12 Water resistance test
Ambient temperature
20±15
Relative humidity
Lifting control
Blow air for 10s every 15min
Above 6000
Test time
Perform according to the test method and conditions of IPX3 in GB4942.2, the water spraying time is 30min, and then carry out the inspections of 4.7.2, 4.7.3 and 4.7.6.
6 Inspection rules
6.1 Factory inspection
6.1.1 The pressure gauge shall be inspected and qualified by the inspection department of the manufacturer before it can be shipped out of the factory. The inspection items include 4.5, 4.7.2, 4.7.3, 4.7.4, 4.7.5 and 4.7.6.
6.1.2 Factory inspection shall be carried out in accordance with the provisions of GB2828, using a normal inspection and one-time sampling plan, with a general inspection level of 1. Under normal circumstances, the inspection batch is 91-150, and the qualified quality level shall be determined in accordance with the provisions of Table 9 or by negotiation between the supply and demand parties. Table 9
Inspection items
Moving state of movable parts
Basic error
Overload performance
Withstand voltage performance
Pointer response time
Surface quality
In the inspection, if the number of unqualified items for each item is equal to or less than the corresponding qualified judgment number A. , then accept the batch of products, otherwise check each item piece by piece.
6.2 Type inspection
6.2.1 The pressure gauges for type inspection shall be selected from the same batch of pressure gauges that have passed the factory inspection. The number of pressure gauges shall not be less than 9. They shall be re-inspected according to the factory inspection items. After passing the re-inspection, the products shall be evenly divided into 3 groups. 6.2.2 The inspection items for each group shall be in accordance with the provisions of Table 10. 6
Group 1
JB/T 7696.1-95
Group 2
Voltage influence test
Water resistance
Dust resistance
Temperature influence test
Vibration test
Acid and heat resistance
Coating and plating inspection
Sister 3
Durability test
6.2.3 In the test, if one item fails, it is allowed to re-sample double the number of products and re-check the failed item. If there are still unqualified items, the batch of products will be judged as unqualified. 7 Marking, packaging, transportation and purchase and storage
Each pressure gauge should be marked with the manufacturer's name, product model, specification, trademark and standard number. 7.1
7.2Each pressure gauge is wrapped with plastic film and then packed in a foam packaging box. The outer surface of the packaging box should be marked with: manufacturer's name and address;
Product name, product model:
Quantity and factory year and month
7.3Put the color box into a packaging box with protective fillings, and the outside of the packaging box should be marked with: a.
Name and address of the receiving unit:
Product name, specification and quantity:
Name and address of the shipping unit;
Anti-pressure, anti-shock, anti-drenching, and handle with care. 7.4 The documents accompanying the packing should include the product certificate and product manual. 7.5 The packed pressure gauges should be placed in a ventilated and dry room with a storage period of one year (calculated from the date of entry into the warehouse by the manufacturer). When the storage period expires after one year, the pressure gauge should still comply with the provisions of this standard. 8 Warranty period
Under normal use and maintenance conditions by the user, if the pressure gauge is damaged or cannot work normally due to poor manufacturing within 12 months from the date of delivery (based on the date of the invoice), the manufacturer shall be responsible for free repair or replacement. Additional notes:
This standard was proposed and coordinated by the Tianjin Engineering Machinery Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Tianjin Engineering Machinery Research Institute of the Ministry of Machinery Industry and the Shanghai Oriental Instrument Factory. The main drafters of this standard are Yang Chengce and Zhuo Liwei. 7
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