# Where, physically speaking, are CO2, Hydrogen and Methane ventilated on the ISS

My question refers to the location of the Hoses (if I can call it that), which ventilate the by-product of water processing overboard (CO2, H and CH4). I found great sources on how the ISS ECLSS material flow works at other Q here, but I can't find exactly where the vents are placed outside in that sources or others. I believe it is placed on Destiny or NODE 3, but still without sure which one is active nowadays and the exact location. I saw in this week's on-orbit ISS report that there was LSR Deactivation by the ground team. If possible, I would also like to know if this could cause any flow of that material overboard.

• slightly related: Why vent $CO_2$ and $H_2$ waste products to space on ISS? – uhoh May 21 '20 at 5:26
• I did read that other question before (a great Q and answers too), but it does not answered my question. – Apaiss May 21 '20 at 16:08
• Yep, linking related questions in comments helps the site by 1) triggering them to be listed in the right sidebar permanently under "Linked", 2) providing background information and references that might be helpful to those writing an answer here, and 3) potentially inspiring new questions. – uhoh May 21 '20 at 22:04
• As a side note, all the propulsive attitude control thrusters and fuel for those are on the Russian side – CourageousPotato May 22 '20 at 17:24
• @CourageousPotato yep, it can be with Zvezda or Progress, and coincidentally to your comment, they made an attitude correction yesterday with thrusters, as the report shows. Maybe to receive HTV9 monday. – Apaiss May 22 '20 at 19:02

The Regenerative Environmental Control System and Life Support System (ECLSS) racks are currently located in Node 3. This picture from a presentation about the Robotic External Leak Locator shows the location of the vents.

This picture is quite old but is the clearest one in the presentation showing the locations.

Differences between the current Node 3 configuration and this picture:

• Pressurized Mating Adapter 3 (PMA-3) has been removed from Node 3
• Bigelow Expandable Activity Module (BEAM) has been added to Node 3
• Permanent Multipurpose Module (PMM) has been added to Node 3

There are other pictures in the reference showing the configuration after BEAM was installed, but before it was inflated.

This presentation says the Sabatier system was removed from the ISS in 2017, so presumably methane is is no longer vented. But when there was, it used the CO2 vent shown.

I've asked a followup question about the removal of the Sabatier: Why was the Sabatier system removed from the ISS USOS?

References:

• Thank you, this answer, especially the figure, has been very useful for me. I can perfectly understand the current configuration in relation to your old picture. – Apaiss May 21 '20 at 17:56
• I'm new here and I don't know if I should open a new question or ask here. If H2 or CO2 is vented, could they become small pieces of ice at extreme temperatures outside the ISS when they come out of the vents? – Apaiss May 26 '20 at 19:58
• @Apaiss in my opinion that would be a great question. – Organic Marble May 26 '20 at 20:05
• ok, I will do that Q. :) ty! – Apaiss May 26 '20 at 20:10