Scope of use of soft polyvinyl chloride pipes

1. Theme and Scope of Application
This standard specifies the classification, technical requirements, test methods, inspection rules and markings, packaging, transportation, and storage of flexible polyvinyl chloride pipes (hereinafter referred to as hoses) for fluid transportation.
This standard is applicable to plastic hoses used for fluid transportation using polyvinyl chloride resin as the main raw material and extruded. This hose can be used to transport certain suitable fluids at room temperature.
Inner diameter 3-10mm, with a pressure of 0.25MPa; The inner diameter is 12-50mm, and its operating pressure is 0.2MPa.
2 Referenced standards
GB 1.3 Guidelines for Standardization Work – Product Standard Writing Regulations
GB 1040 Methods for tensile testing of plastics
GB 2828 Sampling Procedures and Tables for Batch Inspection by Attribute (Applicable to Inspection of Continuous Batches)
GB 7141 Plastics – Hot Air Aging Test Method (Thermal Aging Phase Method) – General Provisions
3 Product Models
The name of the hose used for fluid transportation is represented by LS, and the specification is represented by d ×δ Represent.
If the inner diameter (d) is 5.0mm and the wall thickness is（ δ） The model of the 1.0mm LS pipe is LS-5.0 × 1.0.
4 Technical Requirements
4.1 The inner diameter, wall thickness, and limit deviation should comply with the provisions of Table 1 (omitted).
Note: The user and the manufacturer can negotiate to produce other specifications of hoses.
4.2 Appearance
The inner and outer walls of the hose should be smooth, uniform in color, and free from bubbles, decomposition discoloration lines, and impurities above 1mm. For impurities below 1mm, there should be no more than 10 impurities within 1mm, but they should not aggregate into groups.
4.3 Color
The color of the hose can be: natural transparent or semi transparent.
Note: The user and the manufacturer can negotiate to produce hoses of other colors.
4.4 Length
The length of the hose shall not be less than 10m.
4.5 The physical and mechanical properties should comply with the provisions of Table 2 (omitted).

5 Test methods
5.1 Dimensions
5.1.1 Sample pretreatment, place at 23 ± 2 ℃ for more than 20 hours.
5.1.2 Measure the inner diameter using a caliper with an accuracy of 0.02mm and a plug gauge with a taper of no more than 1:20; Take a 30mm long and untwisted pipe section vertically cut from the sample as the sample. Gently rotate the sample and place it naturally on the corresponding plug gauge. When there is no gap on the circumference between the sample and the plug gauge (but be careful not to use force to prevent the pipe diameter from expanding), use a 0.02mm caliper to measure the distance between the sample and the end of the plug gauge, and then use the interpolation method to calculate the inner diameter of the sample.
5.1.3 Measure the wall thickness using a precision of 0.02mm card size; After measuring the inner diameter, do not remove the sample. Measure three outer diameter values at an interval of 120 ° between the edges of the sample, and use the difference between the average value and the inner diameter as the wall thickness.
5.2 Appearance
Visually inspect under natural light. Impurities should be measured using a caliper with an accuracy of 0.02mm. If there is any objection, a reading microscope with an accuracy of 0.01mm should be used for measurement.
5.3 Testing methods for physical and mechanical properties
5.3.1 Determination of tensile strength and elongation at break
5.3.1.1 Sample
For hoses with a nominal inner diameter less than or equal to 8mm, take the pipe material for direct testing, and the total length of the metal 3d printing buddha statue sample sample is 150mm; Hoses with an effective length of 50mm and a nominal inner diameter greater than 8mm shall be tested using Type III specimens as specified in GB 1040.
5.3.1.2 Test method
According to GB 1040, the lifting speed is 250 ± 50mm/min.
5.3.2 Determination of thermal aging performance
5.3.2.1 Sample
According to 5.3.1.1, take 10 samples.
5.3.2.2 Test equipment and requirements
a. The aging test chamber should comply with the provisions of GB 7141. The average wind speed is 0.5 ± 0.1m/s; The air replacement rate is 8-20 times/h.
b. Tensile testing machine
5.3.2.3 Test steps
Hang five samples vertically in the middle of the old box at 120 ± 2 ℃, with a distance of no less than 20mm between the samples. After holding for 6 hours, immediately remove them from the aging box. After 20 hours at 23 ± 2 ℃, measure the tensile strength and elongation at break simultaneously with the other five samples that have not undergone overheating aging test.
5.3.2.4 Calculation of test results
a. Calculate the change rate of thermal aging tensile strength according to equation (1):
(1)
In the formula: V1- Change rate of thermal aging tensile strength,%;
δ—— Tensile strength before thermal aging, MPa;
δ—— Tensile strength after thermal aging, MPa.
b. Calculate the change rate of thermal aging fracture elongation according to equation (2):
(2)
In the formula: V2- Change rate of elongation at break during thermal aging;
ε—— Tensile strength before thermal aging, MPa;
ε—— Tensile strength after thermal aging, MPa.
5.3.3 Hydrostatic test
5.3.3.1 Sample
lengthGreater than or equal to 60mm, quantity 3 segments.
5.3.3.2 Test instruments
Hydraulic testing machine, sealing joint.
5.3.3.3 Test steps and result evaluation
Cover both ends of the sample with sealing joints, leaving one end in a free state. Fill the sample with 30 ± 2 ℃ water, connect the press, and remove air. At this temperature, let it stand for at least 1 hour, and then pressurize it with water at the same temperature to 0.5MPa for 5 minutes. The sample is considered qualified if there is no fracture. All three specimens should pass. If the fracture phenomenon occurs within 30mm from the sealing joint, it should be invalidated and additional samples should be taken for testing.
5.3.4 Cold resistance test
5.3.4.1 Sample
Take 3 hoses with a length of 10mm.
5.3.4.2 Test instruments
As shown in Figure 1 (omitted), it consists of a movable flat plate from top to bottom, a support table (with a groove in the center for placing samples), and a handle plate group.
5.3.4.3 Test steps and result evaluation
Use an appropriate casting method to maintain a distance of approximately 60mm between the flat plate and the table. Place the sample in the groove in the center of the table, and then place the instrument with the sample in a low-temperature liquid tank at -10 ± 2 ℃ for 5 minutes. Lower the handle to press the sample, use your hand or wooden hammer to quickly press it onto the handle, lift the handle, and take out the sample. Three samples are considered qualified if there are no cracks or breakage.
5.3.5 Immersion test
5.3.5.1 Sample
Cut 3 samples with a mass of approximately 5g from the hose.
5.3.5.2 Test instruments
a. Analytical balance with an accuracy of 0.1mg.
b. A dryer containing silicone or other desiccants.
5.3.5.3 Calculation of test steps and results
5.3.5.3.1 Water immersion test
Place three samples in a desiccator for 24 hours, take out and weigh (m0) accurately to 0.0001g, and then sink the samples into a beaker filled with distilled water at 50 ± 2 ℃ for 24 hours. Take out the samples from the beaker, use filter paper to absorb the water on the inner and outer surfaces of the samples, and weigh (m2). Place it in an oven at 50 ± 2 ℃ for 9 hours, and then weigh (m1).
a. Calculate the water absorption rate according to equation (4):
(4)
In the formula: Wa – Water absorption rate,%;
M0- mass before impregnation, g;
M1- mass after immersion, g;
M2- Mass after immersion, g.
b. The extraction rate is calculated according to equation (5):
(5)
In the formula: Wb – Extraction rate,%;
M0- mass before impregnation, g;
M1- Immersion