The Sokol suit used for launch and reentry appears to have three hose ports, which all appear to be an anodized blue color. Why aren't the hose connectors color coded?

In contrast, the Apollo suits had 4 hose connectors. Two were colored blue as inlets for inhaled air, and two were outlets for exhaled air.

Sokol suit

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  • $\begingroup$ The blue cylinder in the upper center of the chest is the relief valve, not a connector. The gray umbilical is electrical. $\endgroup$ Mar 27, 2020 at 13:15

1 Answer 1


The Sokol suit does not use a hose for gas inlet and another for outlet. There is no outlet hose.

Gas exhaust flows through the blue pressure relief valve at the centre of the chest; this valve also regulates the pressure of the suit.

Hoses for air and emergency oxygen are connected at the left abdomen of the wearer. See the dual hose at the right side of the image, thick hose for air, thin hose for oxygen.

The connector above the right abdomen is for electrical connections, microphone, earphones and biomedical.

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Color coding of the connectors is not neccessary, the electrical connector does not fit to the gas inlet.

When the pressure inside the capsule is nominal (above 600 mbar), air is flowing into the suit and leaves the suit over the pressure relief valve. Air is recyled and regenerated by the life suport system of the capsule.

Oxygen is used only in an emergency when cabin pressure falls below 600 mbar. The pressure relief valve is used for oxygen too. Oxygen is not recycled or regenerated.

Using the English and German version of Wikipedia about the Sokol suit.


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