As a supplier of PE-RT pipes, I understand the crucial role that oxygen barrier performance plays in the functionality and longevity of these pipes. PE-RT, or Polyethylene of Raised Temperature resistance, is a popular choice for various applications, including floor heating systems, hot and cold water distribution, and radiator connections. Ensuring that PE-RT pipes have effective oxygen barrier properties is essential to prevent corrosion in the heating and plumbing systems, extend the lifespan of the pipes, and maintain the overall efficiency of the system. In this blog post, I will share some methods on how to test the oxygen barrier performance of PE-RT pipes.
Understanding the Importance of Oxygen Barrier in PE-RT Pipes
Before delving into the testing methods, it's important to understand why oxygen barrier is so important for PE-RT pipes. In heating and plumbing systems, oxygen can dissolve in the water and cause corrosion of metal components such as radiators, boilers, and pumps. This corrosion not only shortens the lifespan of these components but also reduces the efficiency of the system, leading to higher energy consumption and potential breakdowns. A good oxygen barrier in PE-RT pipes can prevent oxygen from diffusing into the water, thus protecting the metal components and ensuring the long-term stability of the system.
Methods for Testing Oxygen Barrier Performance
1. Gravimetric Method
The gravimetric method is one of the traditional ways to measure the oxygen transmission rate (OTR) of PE-RT pipes. This method involves placing a sample of the pipe in a controlled environment with a known oxygen concentration on one side and a low-oxygen or oxygen-free environment on the other side. Over a period of time, oxygen will diffuse through the pipe wall. By measuring the weight change of the pipe sample or the oxygen absorber on the low-oxygen side, the amount of oxygen that has passed through the pipe can be calculated.
The steps for the gravimetric method are as follows:
- Sample Preparation: Cut a representative section of the PE-RT pipe with a specific size and shape. Make sure the sample is clean and free from any surface defects.
- Installation in the Test Chamber: Place the sample in a test chamber that can maintain a constant temperature and humidity. Connect the high-oxygen side to a source of oxygen with a known concentration and the low-oxygen side to an oxygen absorber or a chamber with a low oxygen level.
- Measurement: Weigh the sample or the oxygen absorber at regular intervals. The weight change over time can be used to calculate the oxygen transmission rate.
The advantage of the gravimetric method is its simplicity and relatively low cost. However, it is a time-consuming process, and the results may be affected by factors such as temperature, humidity, and the accuracy of the weighing equipment.
2. Coulometric Method
The coulometric method is a more advanced and accurate way to measure the oxygen transmission rate of PE-RT pipes. This method is based on the principle of electrochemical oxidation of oxygen at a cathode. When oxygen diffuses through the pipe sample and reaches the cathode, it is reduced, and an electric current is generated. The magnitude of the current is proportional to the amount of oxygen that has passed through the pipe.
The steps for the coulometric method are as follows:
- Sample Preparation: Similar to the gravimetric method, cut a representative section of the PE-RT pipe.
- Installation in the Test Cell: Place the sample in a test cell that contains an electrolyte solution and two electrodes (a cathode and an anode). Connect the high-oxygen side to a source of oxygen and the low-oxygen side to the test cell.
- Measurement: Measure the electric current generated at the cathode. The oxygen transmission rate can be calculated based on the current value and the calibration curve of the test equipment.
The coulometric method has several advantages over the gravimetric method. It is more sensitive, can provide real-time results, and is less affected by environmental factors. However, the equipment for this method is more expensive, and it requires more technical expertise to operate.
3. Infrared Absorption Method
The infrared absorption method is another non-destructive way to test the oxygen barrier performance of PE-RT pipes. This method is based on the fact that oxygen molecules absorb infrared light at specific wavelengths. By measuring the absorption of infrared light by the oxygen that has passed through the pipe sample, the amount of oxygen can be determined.
The steps for the infrared absorption method are as follows:
- Sample Preparation: Prepare a pipe sample as described in the previous methods.
- Installation in the Test System: Place the sample in a test system that consists of an infrared light source, a detector, and a chamber for holding the sample. The high-oxygen side of the sample is exposed to oxygen, and the low-oxygen side is connected to the detection chamber.
- Measurement: Measure the intensity of the infrared light before and after it passes through the oxygen in the detection chamber. The difference in intensity can be used to calculate the oxygen concentration and the oxygen transmission rate.
The infrared absorption method is fast, non-destructive, and can be used for on-line monitoring. However, it may be affected by the presence of other gases that also absorb infrared light, and the calibration of the equipment is crucial for accurate results.
Factors Affecting Oxygen Barrier Performance
In addition to choosing the right testing method, it's important to understand the factors that can affect the oxygen barrier performance of PE-RT pipes. These factors include:
- Material Quality: The quality of the raw materials used in the production of PE-RT pipes, especially the oxygen barrier layer, has a significant impact on the oxygen barrier performance. High-quality materials with good oxygen barrier properties should be selected.
- Pipe Wall Thickness: Generally, a thicker pipe wall can provide better oxygen barrier performance. However, the thickness should be optimized to balance the cost and the mechanical properties of the pipe.
- Processing Conditions: The processing conditions during the pipe manufacturing process, such as temperature, pressure, and cooling rate, can affect the structure and properties of the oxygen barrier layer. Proper processing parameters should be used to ensure the integrity of the oxygen barrier.
- Environmental Conditions: Temperature and humidity can also affect the oxygen transmission rate of PE-RT pipes. Higher temperatures and humidity levels usually increase the oxygen transmission rate.
Conclusion
Testing the oxygen barrier performance of PE-RT pipes is an important step to ensure the quality and reliability of these pipes in heating and plumbing systems. There are several methods available, each with its own advantages and disadvantages. As a PE-RT pipe supplier, we are committed to providing high-quality pipes with excellent oxygen barrier properties. We use advanced testing equipment and strict quality control procedures to ensure that our PERT Pipe and PERT Tubing meet the highest standards.
If you are interested in our PE-RT pipes or have any questions about oxygen barrier performance testing, please feel free to contact us for further discussion and potential procurement. We look forward to serving you and contributing to the success of your projects.
References
- ASTM D3985 - Standard Test Method for Oxygen Gas Transmission Rate Through Plastic Film and Sheeting Using a Coulometric Sensor.
- ISO 15105 - 1:2007 - Plastics - Determination of the gas - transmission rate of films and thin sheets - Part 1: Differential - pressure method.
- DIN 4726 - 2001 - Pipes for heating systems; polyethylene pipes (PE - RT) with oxygen diffusion barrier; requirements and testing.
