There is a story that the door of Brahman is a steam valve, and it seems to be partially true. Perhaps, it is like that in the dimension of prana or the astral dimension.

This hole is like an exhaust valve. In a steam locomotive, if the pressure is too high, it will be released from the exhaust valve. In any case, if the Sahasrara is not opened, energy may accumulate too much and cause various problems in the body, so before meditation, it is necessary to first purify the Sushumna and allow prana to flow smoothly from the top of the head. "From Honzan Hiro's Collected Works 5."

This is often said in yoga, and famous figures in the esoteric tradition and those who are raising Kundalini in Qigong have said similar things, so I think that is probably the case.

On the other hand, as it is said in spirituality, the Sahasrara is also a long pipe that extends upwards and connects to the heavens. In spirituality, the Sahasrara is not a steam valve, but an important route and pipe for connecting to the heavens.

Similarly, in spirituality, there is also a pipe extending downwards, which is considered a grounding pipe, and the upper and lower pipes are treated as important, with the upper pipe connecting to the higher self or God.

In yoga, there are similar stories, but in yoga, the Sahasrara is often described as a symbol of 1000 petals, spreading in a semi-circular shape around the top of the head. In this regard, unlike spirituality, the image of it extending upwards is less common, and although some scriptures may mention it, the prevailing view is that it spreads in a semi-circular shape around, as shown in the diagrams of the Sahasrara.

In yoga and Vedanta, the entire surrounding world is described as being identical to oneself, and it seems that the upper direction is not particularly emphasized. Yoga talks about the individual Purusha, which is also the Purusha of the world, and thus talks about the individual and the world in parallel. Vedanta says that the individual Atman is actually identical to Brahman, which is the whole, and while it talks about the individual and the whole being the same, it does not talk much about "direction."

In yoga, it is important to raise Kundalini to the Sahasrara at the top of the head, and it is also explained that it is then raised to the heavens. However, this is more about expanding consciousness to the surrounding world, rather than raising it to the heavens.

However, personally, I feel that Sahasrara is not just a steam valve, but a pipe that connects to the heavens. In reality, I don't know where it connects, but it extends far upwards, and it feels like it reaches another dimension. There is a sense that it is connected to the surrounding space, but I feel that it is more like a pipe that connects to the heavens.

Perhaps, the idea of a steam valve is something that exists in the dimension of the mind or the astral plane. It might be a bit of a waste of energy, but it may also have that role. On the other hand, if it goes further, it feels like a pipe extends from Sahasrara to the heavens, and it's more like a pipe, or perhaps a better way to put it is that a "pillar of light" extends.