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What is the difference between a virtual vacuum leak and a vacuum leak?
A real leak would be defined as air or gas leaking through a vessel from the outside of the vessel into the evacuated space. A virtual leak is not a through the vessel situation, it is gas being slowly released into the evacuated space from a place where it is trapped, e.g. a bolt in a blind hole.
A real leak would be defined as air or gas leaking through a vessel from the outside of the vessel into the evacuated space. A virtual leak is not a through the vessel situation, it is gas being slowly released into the evacuated space from a place where it is trapped, e.g. a bolt in a blind hole.
See lessWhat leak detection methods are considered to be the most effective for locating small leaks?
Small leaks in a vacuum system are easily detected with a helium mass spectrometer. Helium leak detection is very effective
Small leaks in a vacuum system are easily detected with a helium mass spectrometer. Helium leak detection is very effective
See lessWhy would a rotary vane pump smoke?
Most likely the pump is operating at a higher pressure than it was design for. Smoke is typically oil vapor carried by the gas (air) leaving the pump.
Most likely the pump is operating at a higher pressure than it was design for. Smoke is typically oil vapor carried by the gas (air) leaving the pump.
See lessWhy use partial pressure in a vacuum furnace?
Partial pressure is typically used to raise the pressure in the furnace above the vapor pressure of the material being heated, thus minimizing the out-gassing of certain constituents of the material
Partial pressure is typically used to raise the pressure in the furnace above the vapor pressure of the material being heated, thus minimizing the out-gassing of certain constituents of the material
See lessCFC, Graphite, or Moly, which is the best choice for vacuum ovens?
Hot zones are the hearth of every vacuum furnace. When purchasing a new furnace, you might face with the Hamletic doubt about hot zones: graphite-based or all-metal design hot zone? That’s the question! The graphite wafer is an excellent material. It allows operation at very high temperatures (up toRead more
Hot zones are the hearth of every vacuum furnace. When purchasing a new furnace, you might face with the Hamletic doubt about hot zones: graphite-based or all-metal design hot zone? That’s the question!
The graphite wafer is an excellent material. It allows operation at very high temperatures (up to 3000°C based on the vacuum level), has low density, reduced weight and modest thermal capacity. It creates the ideal black body conditions (emissivity about 1) inside the heating chamber for obtaining high uniformity.
All-metal hot zones are used in high demand industries where sensitive materials are processed, such as aerospace, electronics and medical. There are heat treatments that require a particularly clean environment or extreme vacuum levels. There may be different reasons: in some cases the chamber’s graphite could interfere with the process, resulting in unwanted carburation of the pieces treated. In other cases, the load could be particularly sensitive to the presence of residues in the oxygen or hydrogen atmosphere (which could lead to embrittlement of the pieces), and so graphite wafer degassing during the cycle could be damaging. In these circumstances, the user should opt for all-metal heating chambers (shields and resistor).
If you want more information on this topic and a detailed analysis of the differences, take a look at the following 2 articles:
See lessVacuum furnace hot zone: graphite vs all-metal design [1/2]
Vacuum furnace hot zone: graphite vs all-metal design [2/2]