We need a pump that is capable of evacuating warm air 130-200 C and between 30-150 liters during 3-5 minutes. The suction lift should around -0.9 - -0.5 bars. Any clue?

You need an Exhaust Fan

Not if Mr. Francke's source of air is closed ( which I think it is as he has given the pressure values). Well Hans, the air is warm so no condensation will be worth the money.You need a vacuum pump -perhaps a rotary lobe vacuum but the more the pressure differential of your warm air, the more expensive and complicated the pump system will be. Now 1 bar is atmospheric pressure so you will be going towards absolute zero..I don't think I am competent enough to comment on that.Anis probably missed the pressure part.

Thank you Arindom, do you think a Venturi will do?

Hans, yes a venturi eductor can evacuate the air from a vessel head space or a confined vessel and mix it with a liquid which would be the motive force, but the thermal transfer has to be caculated based on the KCals of the liquid temperature being pumped and the hot air when mixed if your ultimate goal is to heat a liquid. The size of the pump and venturi would be based on scfm and strength of the vacuum needed (assuming ~29.8 for efficiency) as well as placement to ensure that the air is directed to the venturi air inlets. This is a common configuration our clients have used in industrial applications to remove hot gases contaning H2S from the headspace of tanks or to introduce a gas to be mixed into a liquid such as CO2 (pH control) or O2 for supporting biological and chemical reactions.

Hi John, .
Thanks for that bit of info. I will be interested inknowing more about your venturi eductors. Perhaps you can mention a link which I can follow.

Hi John, the purpose is not to use the warm air for heating. We only need to evacuate the air volume and such the water through.

Once the warm air is evacuated(after 3 to 5 minutes) what then??
Will the pump then pump a liquid or is it to be designed purely to evacuate 30 to 150 ltrs of dry air in 3 to 5 minutes.

Designed to purely evacuate. After the air is evacuated another circulation-pump will suit for the curculation.

So this is a pump priming arrangement??
Can you let me know what is being pumped and possibly a bit of detail on the process. The dry air is very hot so whatever is being pumped, once the circulation pump is primed, will no doubt also be very hot??

Hi John, yes the purpose of the Venturi is to prime the circuit.
We have a drain-back system - that is; the solar collectors are empty when not in operation. Once there is a temperature difference that justify to circulate the water, the Venturi will empty the collectors for air and a second pump will start pumping for circulation. This is not difficult.
The difficulties arise when we have stagnation; no water usage and still a lot of energy from the sun. Then the circulation has to stop in order to avoid boiling. During stagnation we may see temperatures between 100 and 230 C.
If there is hot water usage during this state, the circulation will start again and we have to evacuate the warm air.
The water that circulate will never be any warmer than 80 C at inlet and 95 C at outlet.