Hello Roger,

I need to use a DT 800 in a hot environment (70 degC) and under low pressure (nearly vacuum). The logger should stand the temperature but what is about the flash card and the low pressure?

The logger should be in this environment for nearly on month so that a temp. shield is not really helpful.

Best Regards,
Thomas

Good morning Thomas,

Now that is a question I have never been asked before!!
I will ask Engineering.

Cheers,
Roger

Good morning Thomas,

What level of vacuum are you talking about?

Cheers,
Roger

Hello Roger,

The vacuum is about 10 mBar

Greetings,
Thomas

Good morning Thomas,

We really can't answer this one. We simply don't know the effects of vacuum on many of the components.

Cheers,
Roger

Dear Roger, dear Thomas,

Please let me introduce myself very shortly. The original question that was asked by Thomas is a result of an inquiry of my company to Thomas. We want to use a data logger in a 10 mbar and 70 degrees centigrade environment. The temperature will be held continuously, the pressure changed between ambient pressure and 10 mbar every two hours approximately.

There are two questions that arise in combination with the "vacuum":

1. Are there components that will be destructed under vacuum? For example, capacitors with electrolytes may boil or leak. Resistors, transistors or capacitors without electrolytes should not be affected. Overall, there should not be many components that are annoyed by vacuum and these might be identified easily.

2. The heat dissipation could become a problem as components may rely on heat conduction to dissipate heat. Under 10 mbar, the heat conduction is severely restricted.

As all other features of the DT-800 fit with our demands well, we really would like to use this data logger. However, we have to be more confident to use it in 10 mbar environment. Perhaps you could shed some more light on the vacuum question.

With regards,
Christian Dannert

Good morning Christian,

The first concern is the batteries, both the lead acid and Lithium if they leak then the chemicals will boil off and the corrosive atmosphere would be disastrous for the electronics. Then there are the effects of out gassing on the components and operation of the components at high vacuum.

Data on some of the components like memory cards would have to be gathered from manufacturers (if they have it). I have just spoken to our hardware people and their response is as follows.

Things of immediate concern:

1. Electrolytic capacitor on charger PCB
2. Lithium on Charger PCB
3. Tantalum capacitors
4. System 12V Lead acid battery
5. Wima MKS capacitor (I think ok) on Analog PCB
6. Analog Power supply. I suggest running logger from 24 V instead of 12 V this way the Switch Mode Power Supply won't have to work so hard.
7. PCMCIA cards (We don't now what components are used, but in all likelihood should be OK)

Recommend that you run extension wires to the 12 V lead acid battery that is outside your environment. Or remove it altogether.

You can remove the lithium battery. If you do this the RTC and data stored in SRAM will be lost if the plug pack power supply is turned off or fails.

The simplest thing would be to try a DT800 in the vacuum and see what breaks, but we don't have access to a vacuum chamber to test in.

Cheers,
Roger