This standard specifies the method for determining the fluid permeability of permeable sintered metal materials, the pores of which are continuous or interconnected, and the test is carried out under the condition that the fluid permeability can be expressed by viscosity and inertial permeability coefficients. This standard is not applicable to very long small diameter tubular specimens, in which the pressure drop of the fluid through the cylindrical inner hole is not negligible compared with the pressure drop of the fluid through the wall thickness. GB/T 5250-1993 Determination of the fluid permeability of permeable sintered metal materials GB/T5250-1993 standard download decompression password: www.bzxz.net

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National Standard of the People's Republic of China
Permeable sintered metal
materials--- Determination
of fluid permeability
GB/T 5250--93
Replaces GB525085
This standard is equivalent to the international standard IS04022-1987 "Determination of fluid permeability of permeable sintered metal materials". Subject content and scope of application
This standard specifies the method for determining the fluid permeability of permeable sintered metal materials, the pores in the material are continuous or interconnected, and the test is carried out under the condition that the fluid permeability can be expressed by viscosity and inertial permeability coefficients (see Appendix A). This standard is not applicable to very long small diameter tubular specimens, where the pressure drop of the fluid through the cylindrical inner hole is not negligible compared with the pressure drop of the fluid through the wall thickness.
2 Reference standards
5 Permeable sintered metal materials
Determination of oil content
GB/T 5165
3 Symbols and definitions
The symbols and definitions used in this standard are shown in Table 1. Table 1
Permeability
Viscous permeability coefficient
Inertial permeability coefficient
Volume flow rate
Upstream pressure
Downstream pressure
Average pressure
The ability of a fluid to pass through a porous metal under the action of a pressure gradient When the fluid resistance is only the viscous loss, under the action of a unit pressure gradient, the volume flow rate per unit area of ​​a fluid of unit dynamic viscosity through a porous metal When the fluid resistance is only the inertial loss, under the action of a unit pressure gradient, the volume flow rate per unit area of ​​a fluid of unit density through a porous metal Mass flow rate of the fluid Divided by its density
Pressure upstream of the specimen
Pressure downstream of the specimen
Average of upstream and downstream pressures
Pressure difference between upstream and downstream of a porous specimenApproved by the State Technical Supervision Commission on December 24, 1993
Implemented on September 1, 1994
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Pressure gradient
Test area
Dynamic viscosity
Average absolute temperature
Blank pressure drop
GB/T 5250—93
Continued Table 1
Pressure drop produced by unit thickness of porous specimen Ratio of volume flow rate to test area
Area of ​​porous metal perpendicular to the direction of fluid flow Dimensions of specimen in the direction of fluid flow
Length of circular cylinder (see Figure 2)
Density of fluid at average temperature and pressure Coefficient of dynamic viscosity determined by Newton's law Average value of fluid temperature on the upstream and downstream sides of the specimen When the test apparatus is not placed in the test position, the pressure drop observed between the upstream and downstream pressure measuring ports
A test fluid of known viscosity and density is passed through the specimen, and its pressure drop and volume flow rate are measured. Units
Viscous and inertial permeability coefficients are determined by parameters such as pressure drop, volume flow rate, viscosity and density of the fluid, and the geometric dimensions of the porous metal specimen through which the fluid passes.
5 Apparatus
5.1 Fixtures
The fixture is selected mainly based on the shape, size and physical properties of the specimen. This standard provides two different types of fixtures suitable for determining the fluid permeability of porous specimens.
5.1.1 Flat specimen test fixture
This type of fixture is suitable for non-destructive testing of local areas of flat porous specimens. The flat specimen is clamped between two pairs of soft sealing rings. The average diameter of the inner pair of sealing rings is D1, which coincides with the test area; the average diameter of the outer pair of sealing rings is D2, forming a pressurized protective ring around the test area to prevent leakage at the edge of the test area. The width of the protective ring test area should not be less than the thickness of the specimen, that is: D.— D,
The protective ring test area is close to the equal pressure of the inner and outer chambers to minimize edge leakage. On the upstream side of the specimen, the opening connecting the inner and outer chambers is as large as possible; on the downstream side of the specimen, the inner chamber leads to the flowmeter, and the outer chamber leads to the atmosphere through a pressure balance valve. The valve is adjusted to make the pressure of the inner and outer chambers equal.
It is recommended to use "O\ type sealing ring for sealing.
In order to overcome the surface defects and unevenness of porous metal, the sealing ring should be sufficiently soft. In some cases, in order to ensure a leak-free seal, the inner and outer chambers should be loaded with seals respectively. The two upper sealing rings and the two lower sealing rings should match each other (see Figure 1). 288
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Vent to the atmosphere
GB/T5250—93
To the flow meter
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Qa= Q 1
Flowmeter
Figure 1 Schematic diagram of the protection ring test fixture
1—Clamping force; 2—Test fluid inlet, 3—As large as possible; 4—Test sample; 5—Adjustable pressure balance valve: 6—Inner sealing \O\ ring; 7—Outer sealing "0\ ring; 8—Test fluid inlet from the pressure regulating control valve 5.1.2 Test fixture for pipe (simple) test sample The two axial end faces of the test sample are clamped with a fixture to allow the test fluid to pass through the pipe wall from the inside to the outside. As shown in Figure 2, the flow meter is placed upstream of the test sample. In order to overcome the irregularities on the surface of the porous metal test sample, a sufficiently soft sealing ring should be used to ensure sealing. 289
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GB/T5250—93
Flow Gravimeter
Figure 2 Schematic diagram of the test fixture for tubular (simple) specimens 1 Clamping force; 2—Sealing ring; 3-Specimen; 4—Sealing ring Note: Diameter d. Should be close to diameter d, and distance h should be as short as possible to minimize the correction value of the instrument. 5.2 Test fluid
QnQ:
In most cases, gas is used as the test fluid (see Appendix B). The gas should be clean and dry. In the case where liquid is required, the liquid is required to be clean and free of dissolved gas. 6 Specimens
The diameter of the plate specimen should be greater than 100 times the diameter of the powder particles, the thickness should be greater than 10 times the diameter of the powder, and the thickness deviation of the test area should be less than 5%; the length-to-diameter ratio (L/d) of the tubular specimen should not be greater than 3.7 Test steps
7.1 Specimen pretreatment
When necessary, the specimen should be cleaned, grease and foreign matter removed, and dried. The cleaning method refers to GI35165.7.2 Measurement of specimen geometry and area calculation7.2.1 Measuring tool
The size of the micrometer end face should not be greater than the unevenness of the specimen surface and not less than the pore size. 7.2.2 Flat specimen
Measure the specimen thickness and diameter.
7.2.3 Tube (tube) specimen
Measure the axis length and the inner and outer diameters of the end.
D(ln)*
2(← 1)
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