Let's do it:

The phenomenon that causes divers to be trapped is called differential pressure, or Delta P. It requires surprisingly little Delta P to trap divers in such a way that they can't free themselves.

The formula is simple: F=Δp⋅A

Δp = Differential pressure, A = the area the differential pressure acts on, in our case the cross sectional area of the pipe.

Example:

30 cm pipe => A = π⋅(0,15)² m²

Delta P only (!!!) 0.1 bar (= 10 kPa).

F = 10,000 Pa ⋅ 0.07 m² ≈ 700 N. This equals roughly 71 kg of weight.

Now, let's try this with the numbers above. Unfortunately, we don't know the diameter of the pipe so let's again assume 30 cm:

Δp = 21.375 - 14.7 psi = 6.675 psi ≈ 0.46 bar = 46 kPA

F = 46,000 Pa ⋅ 0.07 m² ≈ 3250 N.

=> You would be sucked to this pipe opening with a force of roughly 330 kg. In other words, you're fucked.

For fun, let's assume a 50 cm diameter pipe:

F = 46,000 Pa ⋅ 0.196 m² ≈ 9020 N.

This equals roughly 920 kg of weight.

=> There is absolutely no escape here and I think it's safe to assume the diver would be sucked through that pipe.

And finally, to answer your question (I'll skip the math here), a 10 cm diameter pipe with the same Delta P would mean 37 kg of weight. I think it would be possible to escape in this scenario, but it'll not be effortless.