# Humidity and temperature considerations

I am working on a system similar to a 3D printer, which works with stepper motors, heated bed and an hot air fan. This system will work inside a chamber, with a temperature around 4 degrees and around 50% of relative humidity - These variables are concerning to me. I am wondering what measures should I take to avoid the condensation of droplets and effects related to ESD due to the humidity of the environment, which affects to the PCB integrity and can cause short-circuits.

• How will you maintain 4°C in a chamber with a hot bed and a hot air fan? Jun 7, 2016 at 12:33
• 4 C or 4 F? You need to be careful with units. Jun 7, 2016 at 12:34

A psychrometric chart will give you several useful figures for your calculations. (This answer assumes that you are working in Celsius / centigrade as any civilised engineer would!)

Figure 1. Extract from Psychrometric chart with operating conditions marked on it.

• Find the 50% RH curve (circled top right).
• Mark a point on it above 4°C. This is your operating point.
• The upper red line is the "dew point". When you reach that condensation will appear.

I have marked up in red two possible ways of getting condensation on your part.

1. Increase the relative humidity (vertical arrow). Obviously at 100% RH the air is saturated and water will start to fall out of it.
2. Decrease the temperature (horizontal arrow). You will reach 100% RH at about -6°C.

In short, you have a good safety margin at your operating conditions.

• I have found this link where some prevention considerations are analyzed, but I think they are for a more hostile situation. powerguru.org/effects-of-humidity-on-power-electronics-design Your answers have been very useful and I have learnt a lot from them! Jun 7, 2016 at 13:59

What you describe doesn't sound like much of a problem. Even if you mean 4 °C, there is very little moisture in the air, especially at 50% RH. Any electronics will dissipate some heat, so the board should be slightly warmer than the air. Even if it were the same temperature, I don't see why you expect condensation.

Basically 4 °C and 50% RH shouldn't be a problem.