CSZ EZT-570S, User Manual

Page: 29 / 155

EZT-570S User Manual
29
3.2.1 Standard Chamber Options
The first event is the “switch” that turns the chamber on and off. This will enable air circulators,
pumps, heating/cooling systems and any other components associated with the operation of the
chamber. This event is present on all chambers. Depending on the options provided with your
chamber, additional events may also be present.
3.2.1.1 Humidity Operation
The humidity event turns the chamber’s humidity system components on and off. Note that when
humidity is turned off, the relative humidity is still measured and displayed; however, no control takes
place to obtain the set point value. The humidity system will not operate unless the chamber event is
also turned on.
The operating limits of the humidity system are dependent upon actual chamber temperature and
chamber construction.
Please note the following regarding humidity system operation:
Temperature Extremes
When operating your environmental chamber at extreme air temperature, below freezing (0°C / 32°F)
or above boiling (100°C / 212°F), the chamber is not capable of controlling humidity. This is due to
the physical properties of air and its ability to hold moisture at standard atmospheric pressures when
at these temperatures.
To prevent malfunction or damage to the chamber, the EZT-570S control system automatically
disables the humidity system components when outside of the valid operating temperature range.
The event will remain on; however, so once the air temperature in the chamber returns to the valid
operating range, humidity control will resume at the target humidity set point.
When humidity is disabled due to the chamber air temperature, the corresponding system status
Monitor indicator (RH TMP DISABLE) will illuminate to indicate that this condition is present.
Minimum Humidity Limitations
The standard humidity option provides a lower limit of humidity control relating to a 4.4°C (40°F)
dewpoint. The dewpoint refers to the temperature at which the air contains the maximum amount of
moisture it can hold. When a surface drops to that temperature or below, condensation will occur on
that surface. The dewpoint varies logarithmically with temperature and relative humidity. This means
that at higher temperatures, a much lower humidity level can be obtained because the air can hold
more moisture the warmer it becomes.
For example, an air temperature of 85°C (185°F) and relative humidity of 12% is the equivalent
dewpoint of air at a temperature of 5°C (41°F) and 79%. Both of these values are at the minimum
achievable dewpoint of the chamber, and thus the minimum achievable humidity at the related
temperature. If you were to set the humidity set point at 0% for example, the humidity level would
never reach 0 since the chamber is not capable of removing any more moisture from the air.
The EZT-570S is programmed to determine what the minimum achievable humidity point is at any
given temperature and will control to that limit. Therefore, the system will not overwork itself trying to
reach an unattainable point. This prolongs system life, reduces wear and tear and prevents damage
to humidity system components. Thus, if you set a set point of 0%, you can be confident that the
environment within the chamber will remain as dry as possible at any given temperature within the
operating range.
When humidity is limited due to the fact that the minimum dewpoint has been achieved, the
corresponding system status Monitor indicator (RH LO DEWPOINT LIMIT) will illuminate to indicate