What to do if there is air leakage in the vacuum brazing furnace?

2021-11

The vacuum instrument of the vacuum brazing furnace is within the valid range of use. After the leak detector detects a leak, the protective valve at the vacuum gauge pipe has a problem of air leakage, and the valve should be replaced.
After inspection, it was found that the clearance between the rotor and rotor of the Roots pump, as well as between the rotor and the inner wall of the pump chamber, was within the allowable range. The gear wear was minimal and did not require replacement. However, the bearing was severely worn, so the bearing was replaced. The sealing ring of the shaft head of the Roots pump leaks oil. Replace the sealing ring of the shaft head and the lubricating oil at both ends of the Roots pump. After the repair of the Roots pump is completed, there is no air leakage problem in the leak detection sealing part. The ultimate vacuum degree of the Roots pump can reach 3 × 10-2Pa.
2. Through external leakage testing of the vacuum brazing furnace body and vacuum pumping system, it was found that the valve stem seals of the main valve, pre extraction valve, exhaust valve, pneumatic ball valve, and door seal all had varying degrees of air leakage. After inspection, it was found that the main valve stem seal and the furnace door large ring seal were severely aged, with cracks and air leakage problems. The corresponding sealing rings were replaced. When replacing the sealing ring of the main valve stem, considering the simple aging of the sealing ring under the influence of high temperature, fluororubber is selected as the material.
Fluorocarbon is a very good sealing material that is resistant to high temperatures, various media, low gas release, and superior to other sealing materials, providing necessary guarantees for the sealing here. At the same time, it was found that the valve core, vent valve, valve stem, and sealing components of the pneumatic ball valve were severely worn, so these three valves were replaced.
When detecting leaks at the metal head of a thermocouple, due to the long response time of the leak detection, if there is a small leakage point near the metal head of the thermocouple, it is easy to make a misjudgment. To solve this problem, a special method was adopted: first, the sealing part of the double wire was wrapped in a plastic bag, and then helium gas was introduced into the plastic bag for leak detection. Through the above methods of detection, it was found that the thermocouple itself had a problem of air leakage, so a new thermocouple was replaced.

The main types and operating steps of brazing furnaces

Introduction to relevant knowledge of vacuum brazing furnace

The main types and operating steps of brazing furnaces

Introduction to relevant knowledge of vacuum brazing furnace

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