Identify at a glance by the design: whether it is genuine low-temperature evaporation—no need to check specifications or switch on the unit.

Core principle: Genuine low-temperature operation relies on negative pressure + strong condensation + a rational vapour phase structure; fake low-temperature systems are merely ordinary evaporators with a ‘low-temperature’ label, as their design inherently cannot handle low boiling points.

1. Check for a separate, large-volume gas-liquid separation evaporation chamber

Genuine low-temperature:

Features a dedicated upper evaporation chamber with sufficient headspace above the liquid level to maintain stable vacuum and boiling point; vacuum can be reduced to very low levels, enabling evaporation at 35–45°C.

Pseudo-low-temperature:

The vessel is short and stout with an extremely small vapour space; in some cases, it is simply a modified standard reaction or storage tank. The liquid surface is too close to the top; as soon as a vacuum is applied, the material and foam rush straight into the condenser. The vacuum cannot be raised sufficiently, so only a relatively high evaporation temperature can be maintained; whilst nominally labelled as ‘low-temperature’, the actual temperature is 50–60°C or higher.

2. Assess the condenser configuration and installation location

Genuine low-temperature operation:

Equipped with large-surface-area shell-and-tube or plate-type condensers, providing ample heat exchange capacity; typically vertical with bottom-in, top-out configuration, allowing secondary vapour to flow smoothly from top to bottom into the condenser. Only when the condensation capacity keeps pace can the temperature be suppressed and high vacuum maintained.

False low temperature:

The condenser is undersized, featuring simple tubular coils or even merely jacket cooling; condensation capacity is severely inadequate. As vapour cannot be condensed, the system becomes pressurised, preventing the vacuum from rising, and the evaporation temperature naturally remains high.

3. Check for reliable non-condensable gas venting + vacuum matching

Genuine low-temperature operation:

Features a dedicated non-condensable gas venting branch and a gas-liquid buffer tank; vacuum pumps are selected to match the negative pressure conditions, enabling continuous removal of non-condensable gases and maintaining a stable high vacuum.

Fake low-temperature operation:

Lacks a dedicated non-condensable gas venting system, relying solely on a standard water ring pump connected directly; non-condensable gases become trapped within the system, locking the vacuum level at its upper limit, meaning the evaporation temperature cannot be lowered no matter how it is set.

4. Check the specifications and installation height of the demister

True Low-Temperature:

Equipped as standard with high-grade wire mesh or baffle-type demisters, installed in the upper-middle section of the vapour zone with sufficient headroom; effective demisting even at low vapour velocities, allowing for high vacuum levels and stable operation at low loads.

Fake low-temperature:

Either no demister is present, or a simple mesh is haphazardly installed extremely close to the liquid surface; severe mist entrainment occurs as soon as the vacuum is increased, necessitating artificial pressure elevation and higher evaporation temperatures, making true low-temperature operation impossible.

5. Examine the heating method and heat exchange structure

Genuine Low-Temperature Operation:

Primarily utilises forced circulation heat exchange within the tubes, requiring a low temperature differential and suitable for low-temperature, low-temperature-differential evaporation; features high circulation flow rates and thorough feed circulation, making it suitable for low-boiling-point conditions.

Fake Low-Temperature Operation:

Simple jacket heating with a small number of internal coils; circulation flow rates are low, relying solely on raising the medium temperature for heat exchange; inherently unsuitable for low-boiling-point applications, capable only of high-temperature evaporation, yet mislabelled as low-temperature.

6. Assess the overall system’s密封性 and piping layout

True Low-Temperature:

Fully sealed flanges and vacuum-grade valves; piping is thick-walled, short and smooth, with few bends and pressure-trapping points, ensuring strong vacuum retention capability.

False Low-Temperature:

Numerous flange gaskets and standard atmospheric valves; piping is thin-walled with many bends; the system has multiple leakage points and cannot maintain high vacuum, meaning the evaporation temperature naturally cannot be lowered.