A case of low pressure today!
I went to the facilities of the company Svesda (Звезда), which manufactures our Sokol pressure suits and our seat liners. As you might remember, my personal custom-made Sokol suit, sequential number 422, has been ready for a while. Last February I wore it for two hours with a 0,4 atm of overpressure to make sure it fit properly in an inflated state. If you missed it, that story is in Logbook L-280.
Today I tested the nominal functions of my Sokol in the vacuum chamber, where I spent a couple of hours lying in a Soyuz-type seat and in my custom-fit seat liner. First we leak-checked the suit, just like we’ll do on the launch pad before the start: I manually closed the blue regulator valve and verified that the nominal overpressure was reached within a specified time limit. Then I reopened the regulator and put it back to the nominal setting of 0,4: should the pressure around me drops below 0,4 atm (and obviously that’s the plan of the day), the regulator maintains the internal pressure constant at that value.
After a successful leak check, the chamber door was closed and we started the exercise. First the pressure was lowered to 5 km. It might be confusing to use km as a unit when we’re actually talking about pressure, but it’s pretty typical in a hypobaric chamber. The pressure is referred to the standard Earth atmosphere: when we say that we are 5 km, we mean that the pressure in the chamber is equivalent to what you would have on Earth at 5 km altitude (which is about half of the pressure at sea level).
At 5 km we stopped momentarily, the ventilation was interrupted and the supply of pure oxygen was turned on instead. That’s a much smaller flow – just like it would be in the Soyuz – and from this point on it started to get a bit warmer inside the suit, as we resumed our “climb” to higher altitudes and lower pressures. At 7km I felt the suit starting to inflate and the needle of the gauge showing the suit’s overpressure starting to move from the zero position: the regulator had kicked in, preventing the internal pressure from dropping below 0,4 atm.
Eventually we arrived at 30 km, where the pressure is about 1/100 of the sea level value – for all practical purposes today: vacuum. At that point the suit, still at constant internal pressure, was quite inflated and very rigid. Would be quite a challenge to operate in this state, but hey… I’m certainly not complaining. On a really bad day, it might save my life – just like it protected me from vacuum today!
Photo: Yuri P. Kargapolov
(Trad IT) Traduzione in italiano a cura di +AstronautiNEWS qui:
https://www.astronautinews.it/tag/logbook/
(Trad ES) Tradducción en español aquí:
https://www.intervidia.com/category/bitacora/
(Trad FR) Traduction en français par +Anne Cpamoa ici:
10/04/2014