Views: 13 Author: pqwt Publish Time: 2022-07-14 Origin: PQWT
Different types of leaks behave in different ways. Leak geometry, pressure, material, humidity, temperature, and flow rate are all factors that affect leak performance. Too many interfering factors make leak detection and leak testing a big challenge.
The following are examples of three types that are difficult to detect.
Type 1: Beam Leakage
When using tracer gas leak detection, sometimes you may only be able to locate a very narrow area. At the same time, you get an indication of a leak, but it is far away (a few feet/decimeters) from the test object, so the cause is unknown.
The leak you find may be a very narrow, high-speed beam of tracer gas, almost like a narrow laser beam from a laser. The farther away from the leak, the more the beam spreads out, but even at a significant distance from the leak, the beam may still be very thin and narrow.
The gas beam may hit the operator or surrounding structures and "bounce back", causing the operator to be unsure of the true source location of the beam. By noticing this difficult to detect leak, valuable inspection time can be saved.
Type 2: Aluminum Casting Leaks
Aluminum castings may contain pores that form as a result of gas trapping during the solidification of molten metal. Such pores may be very large and obvious; or they may be very small and not cause much of a problem.
The pores may be completely enclosed within the part, with no openings connecting the surfaces, but they may also be connected to one or both surfaces. The latter case will create a leak path through the aluminum casting.
Leakage points in the casting may be pinhole-like, which in turn may act as a thin pipe through the casting. These leaks are largely predictable. However, leaks can also be porous, a situation that usually involves a large number of very small leak points that collectively contribute to a larger leak. If the leak area becomes large, it may be difficult to detect the leak with a suction gun because the gun cannot detect the overall leak flow.
The most difficult form of leak to detect in metal castings is a leak that connects to a larger hidden cavity that acts as a gas storage cavity during leak testing.
This structure may result in a considerable delay between the gas injection process and the leakage of gas towards the opposite side of the leak point.
As for semi-hidden, fully closed leak points, they are also difficult to detect if a leak test is performed on a "cast" part and if some kind of machining to open such closed leak holes is performed after the leak test.
Tiny air holes can also be blocked during various liquid handling or painting processes. This situation should be carefully considered when deciding where in the production process to perform leak detection.
Typically, it is recommended that a leak inspection be performed after the machining and pickling processes are completed and before surface treatments such as painting, electrochemical coating or oxidation treatments.
Type 3: Insignificant liquid leakage
When a product is tested for liquid leaks, the result may be that the product is not leaking, but if the leak is detected with a tracer gas leak detection method, the leak can be reliably detected.
The leak hole can deliver the leaking liquid to the surface of the leak at such a slow rate that the liquid is evaporated as it reaches the surface on the outside of the object. The liquid evaporates so fast that there is no visible trace at the leak site.
PQWT Pipe leak detector product recommendation