How to Detect Leaks in Plate Heat Exchangers Using Tracer Gas
This document provides an overview of using tracer gas leak detection methods for plate heat exchangers, detailing applications, traditional methods, and INFICON's advanced solutions.
Introduction
Heat exchangers are vital components across various industries, facilitating heat transfer between gases or liquids. Ensuring their integrity through comprehensive leak testing is crucial for reliability, safety, and preventing costly repairs and downtime.
Heat exchangers are used in diverse applications, from power generation and manufacturing to healthcare and data centers, improving efficiency, safety, and energy savings. Their size and complexity vary greatly, from small domestic units to large industrial equipment in power plants, chemical plants, and refineries. This document focuses on leak detection in plate heat exchangers using INFICON's tracer gas leak detection instruments.
Traditional Methods
Common traditional methods for leak detection include pressure decay testing and soap bubble testing.
Pressure Decay Testing
This method involves pressurizing the heat exchanger with air and monitoring pressure changes over time. However, it is sensitive to temperature fluctuations and has limited sensitivity, only indicating the overall seal of the system without pinpointing the exact leak location.
Soap Bubble / Water Immersion Testing
For simpler leak detection, a soap solution can be applied to pressurized components. Bubbles form at leak locations, indicating the presence of a leak. This method is suitable for small leaks in flanges, joints, gaskets, and seals, but its sensitivity is limited. Similarly, water immersion testing involves pressurizing the heat exchanger and immersing it in water, observing bubbles. This method can be difficult for identifying very small leaks due to numerous bubbles and requires visual inspection of all surfaces, which may not be practical for large components or systems in operation. It also necessitates system shutdown and drying.
Image Description: A plate heat exchanger used in automotive applications.
Our Approach: Tracer Gas Leak Detection
Tracer gas leak detection offers a non-destructive and highly sensitive method for identifying even the smallest leaks, which are often undetectable by traditional means. This process typically uses helium (He) or a hydrogen-nitrogen mixture (Formier gas, 5% H2) as the tracer gas.
How it Works
- Evacuate Heat Exchanger: Remove liquids and gases from the heat exchanger to ensure accurate tracer gas filling.
- Pressurize Heat Exchanger: Fill the heat exchanger with the tracer gas at the required test pressure.
- Detect Leak: Measure the concentration of tracer gas in the surrounding environment using a sniffing probe to locate the leak.
INFICON's Solutions
INFICON offers advanced solutions for tracer gas leak detection, providing enhanced sensitivity and accuracy.
Accumulation Test (for small to medium-sized heat exchangers)
For small to medium-sized heat exchangers requiring water/oil leak detection and with low to medium throughput, an accumulation test using Formier gas is an economical solution. The component is evacuated and then pressurized with hydrogen tracer gas. It is placed in a chamber with circulating air. Any leaked hydrogen accumulates in the chamber, increasing its concentration proportionally to the leak size.
INFICON's solution includes the Sentrac leak detector, which can be equipped with dual sniffer probes. The AP29ECO sampling probe, controlled by the Sentrac, samples and analyzes the gas concentration within the chamber over a set period. The AP29ECO features an automatic purge function to clear the system before and after sampling, or when gas concentration exceeds set limits. This allows for the detection of significant leaks within seconds. If the concentration exceeds the threshold, the Sentrac leak detector triggers an alarm. A handheld sniffer probe can then be used to pinpoint the leak location after the overall test, while the component is still pressurized.
Image Description: The INFICON Sentrac leak detector with an AP29ECO sampling probe, displaying a hydrogen concentration reading.
High-Sensitivity Accumulation Test
The LDS3000 AQ leak detector is ideal for fast leak detection, very small leaks, or simultaneous detection of helium and Formier gas. It can detect leaks down to 10-5 mbar·l/s. The component is filled with tracer gas and placed in an accumulation chamber. The LDS3000 AQ measures the rate of increase of tracer gas concentration within the chamber. A rapid increase indicates a significant leak.
Vacuum Leak Test (for large heat exchangers)
For large heat exchangers requiring medium to high throughput testing, or for components needing refrigerant leak testing, a vacuum leak test using helium is the preferred solution. In this method, the heat exchanger is evacuated and filled with helium. A vacuum pump then creates a vacuum within the test chamber. If a leak is present, INFICON's LDS3000 helium leak detector will detect the helium atoms escaping from the heat exchanger and trigger an alarm.
Image Description: INFICON's LDS3000 AQ leak detector.
Advantages of Tracer Gas Leak Detection
- Improved Leak Test Quality: Detects even the smallest leaks.
- Easy Leak Location: Pinpoints leak locations accurately.
- Fast Leak Detection: Provides quicker results and minimizes downtime.
- Clean and Non-Destructive: No need for component disassembly or drying.
- Reliable Results: Unaffected by temperature and humidity variations, ensuring consistent and repeatable measurements.
Summary of Test Methods
| Leak Rate Requirement | Test Type | Seal Type | Throughput | Component Size |
|---|---|---|---|---|
| Low to Medium | Accumulation Test | Water-tight, Oil-tight | Low to Medium | Small to Medium |
| Medium to High | Vacuum Leak Test | Refrigerant Seal | Medium to High | Medium |
For more information, visit inficon.com.
