1. Common pressure unit table
Absolute pressure: the pressure in which the absolute vacuum is the base point is commonly used by SP to express the relative pressure: the pressure at the base point of the atmospheric pressure is usually expressed by GP, also known as the "negative sign" below the atmospheric pressure, and the air tightness leak detection uses the pressure.
Pa
bar
kgf/cm2
atm
at
Torr
mm H2O
mmHg
Psi
1 Pa
1
0.00001
0.00001
0.00001
0.00001
0.0075
0.10197
0.0075
0.00014
1 bar
100000
1
1.01972
0.9869
1.01972
750.062
10.1972
750.062
14.504
1 kgf/cm2
98066.5
0.98067
1
0.9678
1
735.6
10
735.6
14.22
1 atm标准大气压
101325
1.01325
1.033
1
760
10.332
760
14.7
1 at工程大气压
98067
0.98067
1
0.9678
1
735.6
10
735.6
14.22
1 Torr
133.3
0.00133
0.00136
0.00132
0.00136
1
13.6
1
0.01934
H2O 1mm
9.8067
0.000098
0.0001
0.0000968
0.0001
0.07356
1
0.07356
0.00142
毫米水柱
1 mmHg
133.322
0.00133
0.00136
0.00132
0.00136
1
13.5951
1
0.01934
毫米汞柱
1 Psi
6894.76
0.06895
0.07031
0.06805
0.07031
51.7149
703.07
51.7149
1
磅/寸2
2. the necessity of using positive and negative pressure sealing test scheme for automobile radiator
1. the provisions of the new national standard are determined
Test on the sealing performance of 5.1 at room temperature
The detection methods of sealing performance at room temperature are divided into wet and dry tests.
Wet inspection: on the wet seal test table, the radiator inside the sink is compressed air, the commercial car radiator is compressed air with 150kPa, the air of 180kPa compressed by the car radiator, and the pressure holding time is 30s.
Dry inspection: on dry type sealing test rig, 150kPa compressed air is applied to the radiator, and the holding time is 60s.
5.2 temperature low seal test
This test is suitable for radiator with plastic water chamber and rubber sealing strip.
The radiator is injected into the freezing point at -45 C, and the radiator is placed in a low temperature box at -40 C in real vehicle condition. After 10h, the radiator is removed. It is required to complete the release of the coolant in the 10min, and then on the wet seal test table to the radiator inside the sink with 50kPa + 10KPA compressed air to hold the pressure of 60s, and no visible bubbles are allowed during the test.
5.3 pressure static strength performance test
The radiator is internally pressurized with 200kPa or compressed air, and 30s is maintained for 3 times.
In view of the above description, we can choose a positive and negative pressure integrated leak detector to meet the demand.
