SDR (Standard Dimension Ratio) is a standard used to describe the relationship between the wall thickness and the outer diameter of plastic pipes. SDR 21 refers to the ratio of the outer diameter to the wall thickness of the pipe being 21. SDR 21 PVC pipes are usually used in low-pressure transmission systems, such as agricultural irrigation, water supply pipes, and drainage systems. Due to its moderate wall thickness, it can ensure sufficient strength and good economy, and is a widely used type of pipe.
The dimensions of SDR 21 PVC pipes are mainly determined by their nominal outer diameter (OD) and wall thickness (Wall Thickness). Common specifications are as follows:
|
Nominal size (inches) |
Outer diameter (mm) |
Wall thickness (mm) |
Rated pressure (psi) |
|
½" |
21.34 |
1.02 |
200 |
|
¾" |
26.67 |
1.27 |
200 |
|
1" |
33.40 |
1.59 |
200 |
|
1¼" |
42.16 |
2.00 |
200 |
|
1½" |
48.26 |
2.29 |
200 |
|
2" |
60.33 |
2.87 |
200 |
|
3" |
88.90 |
4.24 |
200 |
|
4" |
114.30 |
5.44 |
200 |
|
6" |
168.28 |
8.02 |
200 |
|
8" |
219.08 |
10.42 |
200 |
1. Lightweight and high strength: PVC material has low density, the pipe is light, easy to carry and install, and has good pressure resistance.
2. Strong corrosion resistance: SDR 21 PVC pipe can resist the erosion of most acid, alkali and salt solutions, and is suitable for a variety of water quality environments.
3. Good hydraulic characteristics: The inner wall of the pipe is smooth, the water flow resistance is small, it is not easy to scale, and the water flow is smooth.
4. Easy to connect: It can be glued, socketed or flanged, which is convenient to install and improve construction efficiency.
5. Long service life: Under appropriate conditions, SDR 21 PVC pipe can be used for more than 50 years with low maintenance cost.
1. Water supply pipeline: used in urban and rural water supply systems to transport drinking water, domestic water, etc.
2. Agricultural irrigation: widely used in low-pressure water supply systems such as drip irrigation and sprinkler irrigation in farmland.
3. Industrial pipeline: suitable for the transportation of some chemical fluids with low pressure requirements.
4. Drainage pipes: used for rainwater and sewage discharge systems to ensure smooth water flow.
The smaller the SDR value, the thicker the pipe wall is and the stronger the pressure resistance is. For example:
SDR 13.5: thicker than SDR 21, suitable for higher pressure delivery systems.
SDR 26: thinner than SDR 21, suitable for lower pressure occasions.
SDR 21 PVC pipe is an economical and durable pipe widely used in low-pressure water supply, irrigation, industry and drainage systems. Its reasonable wall thickness design ensures good strength and flexibility while ensuring a long service life. When selecting PVC pipes, the most suitable specifications should be determined according to the specific project needs and refer to the SDR value to meet different pressure requirements and use environments.
