1. Introduction
1. Function:
The pipe negative pressure testing machine is designed and produced according to the working conditions of pipes in actual applications. It is used to determine the maximum negative pressure value of thermoplastic pipes and composite pipes. It is a necessary testing equipment for plastic pipe manufacturers and testing institutions. . This equipment can fully reflect the level of enterprise product quality.
2. Meet the standards:
GB/T19471.2-2004 "Plastic piping system, rigid PVC pipe elastic sealing ring type socket joint, negative pressure sealing test method", ISO 13844: 2000
3. Basic principles:
Insert the plastic pipe socket pipe section into the plastic pipe socket pipe section, make the axis deflection angle of the two pipe sections meet the specified angle, and make the socket pipe section produce a certain deformation, within the specified temperature range, apply two specified negative internals to the sample in turn Press and observe the sealing condition of the sample within the specified test time.
Work frame:
At least two fastening devices are included, one of which is adjustable. While applying negative pressure (relative vacuum) to the sample, it can produce a certain deflection angle at the sample joint.
Clamp: A deformation force can be applied to the socket pipe section at a specified distance from the end face of the socket pipe section.
Vacuum pump: can apply and maintain two specified negative pressures.
Isolation valve: installed between the vacuum pump and the sample.
Sample:
Select the appropriate size. The average outer diameter dem of the pipe should be the minimum within the tolerance range, and the socket size (average inner diameter dem and the diameter of the sealing groove where the seal ring is placed) should be as close as possible to the maximum value specified by the manufacturer.
The free length L of the socket pipe section refers to the distance between the end face of the socket and the end face of the sealing joint of the socket pipe section, which is equal to 5 times the nominal outer diameter dn. The minimum free length L of the socket pipe section is 500mm and the maximum is 1500mm.
2. Composition and configuration of pipe negative pressure testing machine
1. Main box and control system --------1 set
2. Vacuum negative pressure pump -------------1 set
3. Pipe support-1 set
4. Pipe fixture ---------------- with two sets of D225 and D250
5. PLC programmable controller ---------1 set
6. Chinese character LCD touch screen----------1 set
7. Isolation valve and safety valve-1 set each
3. Performance indicators and technical requirements
1. Applicable pipe diameter: 315 or less
2. Main parameters of German BECKER vacuum pump:
① Model: U 4.40 SA/K
② Flow rate (m3/h@50Hz): 410
③ Absolute value of maximum vacuum mbar: 0.5
④ Motor power kW: 1.5
⑤ Rotational speed, revolutions per minute @50Hz: 1450
5. Display accuracy: 0.0002MPa
6. Pressure transmitter: test pressure sampling frequency 0.1 millisecond
7. Timing range: 0—9999h
8. Timing accuracy: 1S
4. Test methods and procedures:
(1) Test method
1. According to the requirements of relevant standards, select the sample to install on the sample rack.
2. Connect the state-adjusted sample to the pressurizing equipment, and then according to the material, size and pressurizing equipment of the sample, when it reaches the test-(0.01±0.002)Mpa (absolute pressure 0.093±0.002 Mpa) Turn off the negative pressure pump to start timing. If the negative pressure changes more than 0.005MPa, stop the test.
If the negative pressure does not change more than 0.005 MPa, continue to apply negative pressure to the sample until the pressure reaches-(0.08 ± 0.002) MPa (absolute pressure 0.023 ± 0.002 Mpa). Disconnect the sample and the negative pressure pump, monitor the pressure for 15 minutes, and record the negative pressure change.
The machine also displays the real-time changes of the pressure curve.
