Leak Detector Information
Underground Water Pipe, Gas Lines, Steam Pipes & Swimming Pools
The Hydro-Lok Underground Leak Detector is the choice for underground pipe and swimming pool applications. The 5/95 Hydrogen mixture is pressurized into the leaking pipe and then can be detected at ground level.
Hydrogen leak detectors for production and service leak detection sniffer trace gas applications. Sniffer leak detectors utilize the inside/out method of tracer gas leak detection. Trace gas is used to pressurize the test part. The sniffer probe of the leak detector is then moved around suspected leak areas until the leak detector indicates that the tracer gas is detected indicating the leak location. Since hydrogen is a flammable gas the concentration of the hydrogen gas is 5% Hydrogen mixed with 95% Nitrogen. This 5/95 blend is below the 5.7% flammability concentration in nitrogen and thus the tracer gas is green label non-combustible and non-flammable.
Other methods of fine tracer gas leak detection have used helium as the tracer gas in the past. Benefits of 5/95 H2/N2 over helium:
- 5/95 is one quarter the cost or less
- Both nitrogen and hydrogen are plentiful with no shortages
- Hydrogen is high energy gas that dissipates once escaping the leak with no background build-up in the area
- Hydrogen sensors are more durable and less expensive than Helium leak detector sniffers
- Hydrogen has low concentrations in air at 0.5 ppm
The 5/95 is an ideal tracer gas for determining leak locations in the field. The most common application is in refrigeration systems. Any refrigeration system in a store location such as big box store or grocery stores can be pressurized with the 5/96 before being filled with refrigerant gas and leak detected. This saves money in reduction of refrigerant loss and helps the environment with reduction of greenhouse gases.
Other service applications include automotive refrigeration systems repair, power plant leak detection, sealed product integrity, re-work leak detection in appliance manufacturing and many more.
The best leak detector for production applications can depend on several factors such as cost, production rate and leak rate.
- VL30 Hydrogen Leak Detector is designed for high production applications for the smallest leak rates.
- VL20 Hydrogen Leak Detector is for high production applications with leak rates > than 0.5 g/yr
- TLD.1000 provides high sensitivity for applications that need a low cost alternative
- TLD.500 is our lowest cost leak detector and good for replacing bubble test type applications
Hydrogen to Replace Helium as the Tracer Gas
In recent years, helium has increased substantially in price along with some scarcity and/or allocation to users. Helium is used in many important applications where there is no substitute. These applications such as medical (MRI), research, space and cooling, require the properties of helium such as for its cooling and scarcity in air. Vacuum leak detection, where vacuum is pulled on a product with the product in a vacuum chamber must also have helium as the tracer gas for its scarcity in air, and that it can be pumped fairly well to meet production leak test requirements.
Hydrogen leak detectors can be used to replace helium leak detectors in sniffing or inside/out leak detection. Using hydrogen tracer gas because of the flammability of hydrogen must be mixed with 95% nitrogen to insure it is non-flammable. By formula, hydrogen under 5.7% in nitrogen is a green label gas and cannot become flammable in any way once mixed.
One key question in looking to replace helium with the 5%H2/95%N2 (5/95) is how well would this tracer gas and leak detector compare to a helium leak detector detecting helium. Helium and hydrogen are both small molecules with low concentrations in air. Helium is 5ppm in air, while hydrogen is 0.5 ppm in air. So detection of either escaping a leak can be readily identified with the leak detector for that gas. Minimum detection is below 1x10e-05 atm cc/sec for each tracer gas. In real world testing between the two gases and leak detectors, both work equally well.
There are a couple of differences that work out in favor of both gases. Hydrogen is higher energy gas than helium, meaning once out of the test piece it dissipates about 3 times faster than helium. This is a great benefit in production since once you have a unit that leaks into the test area, it takes less time for the clean up to occur to allow your operator to begin leak testing again. Also, with helium, in testing subsequent units, false positives can occur as the helium can "hang around" influencing the next test. Downside for hydrogen is that because it dissipates faster, you need to be closer with the probe tip to the leak location. But since the hydrogen leak detectors rely on hydrogen molecules impacting the sensor with no suction in the probe, the sniffer tip can touch the test piece to negate the disadvantage. Helium leak detectors have vacuum to draw in the helium leaking around the test joint. If not kept 1/8" to 1/4" away with the tip, oil, dust and other particles can be drawn into the probe and eventually clogging it.
Since testing indicates that both technologies are equal, then it comes down to economics. Helium is frequently on allocation and the cost is probably 5-6 times the cost of the 5/95 H2/N2 mixture. Hydrogen leak detectors use a replaceable semiconductor sensor technology thus upkeep and maintenance is much less than a helium mass spectrometer or ceramic cell technology. Cost of the hydrogen leak detectors are less also, so economics favor hydrogen in new lines where there is no helium leak detection equipment in place. Facilities that have helium leak detectors and helium reclaim systems can favor helium because the money for equipment has already been spent. So it then comes down to the return on investment and depreciation status of the helium equipment if hydrogen works to replace helium at that moment in time.