Method for separating a gas mixture according to a pressure swing adsorption process (PSA process), comprising the step of separating the gas mixture by adsorbing at least one gas component in an adsorbent mass provided in each vessel of a plurality of vessels (1, 2, 3, 4), wherein each vessel (1, 2, 3, 4) has at least one inlet and one outlet, the method further comprising the step of storing off-gas from said process into an off-gas vessel, wherein in each of said vessels (1, 2, 3, 4) the following steps are to be distinguished of: (i) admitting the gas mixture for a specified period into a first vessel via an inlet of said vessel, and releasing a separated product gas via an outlet of said vessel, to be followed by admitting the gas mixture into a second vessel while continuing the release of product gas from the first vessel, to be followed by (ii) releasing purge gas from the first vessel via its outlet, (iii) releasing off-gas from the first vessel via its inlet and admitting at least part of the off-gas into the off-gas vessel, (iv) admitting purge gas into the first vessel via its outlet, and releasing off-gas from said vessel via its inlet, (v) admitting a separated product gas into the first vessel until the pressure in the first vessel has reached a predetermined value, after which admitting of the gas mixture into the first vessel begins, and the steps are to be repeated beginning with the step (i), wherein during at least one of the steps (iii) and (iv) at least part of the off-gas from the first vessel is released directly to the off-gas consuming device, characterized by (a) connecting, in a first state, in which p i > p b and p i > p o +Δ, each of the vessels (1, 2, 3, 4) directly to both the off-gas consuming device and the off-gas storage vessel, (b) connecting, in a second state in which p i > p b and p i ≤ p o +Δ, each of the vessels (1, 2, 3, 4) directly to only the off-gas consuming device, and (c) connecting, in a third state in which p i < p b and p o > p b, the off-gas storage vessel to the off-gas consuming device, wherein - p i represents the value of the pressure at the inlet, - p o represents the value of the pressure in the storage vessel, - p b represents a pressure having a predetermined value, and - Δ represents a predetermined pressure difference. (i) admitting the gas mixture for a specified period into a first vessel via an inlet of said vessel, and releasing a separated product gas via an outlet of said vessel, to be followed by admitting the gas mixture into a second vessel while continuing the release of product gas from the first vessel, to be followed by (ii) releasing purge gas from the first vessel via its outlet, (iii) releasing off-gas from the first vessel via its inlet and admitting at least part of the off-gas into the off-gas vessel, (iv) admitting purge gas into the first vessel via its outlet, and releasing off-gas from said vessel via its inlet, (v) admitting a separated product gas into the first vessel until the pressure in the first vessel has reached a predetermined value, after which admitting of the gas mixture into the first vessel begins, and the steps are to be repeated beginning with the step (i), wherein during at least one of the steps (iii) and (iv) at least part of the off-gas from the first vessel is released directly to the off-gas consuming device, characterized by (a) connecting, in a first state, in which p i > p b and p i > p o +Δ, each of the vessels (1, 2, 3, 4) directly to both the off-gas consuming device and the off-gas storage vessel, (b) connecting, in a second state in which p i > p b and p i ≤ p o +Δ, each of the vessels (1, 2, 3, 4) directly to only the off-gas consuming device, and (c) connecting, in a third state in which p i < p b and p o > p b, the off-gas storage vessel to the off-gas consuming device, wherein - p i represents the value of the pressure at the inlet, - p o represents the value of the pressure in the storage vessel, - p b represents a pressure having a predetermined value, and - Δ represents a predetermined pressure difference. (a) connecting, in a first state, in which p i > p b and p i > p o +Δ, each of the vessels (1, 2, 3, 4) directly to both the off-gas consuming device and the off-gas storage vessel, (b) connecting, in a second state in which p i > p b and p i ≤ p o +Δ, each of the vessels (1, 2, 3, 4) directly to only the off-gas consuming device, and (c) connecting, in a third state in which p i < p b and p o > p b, the off-gas storage vessel to the off-gas consuming device, wherein - p i represents the value of the pressure at the inlet, - p o represents the value of the pressure in the storage vessel, - p b represents a pressure having a predetermined value, and - Δ represents a predetermined pressure difference. - p i represents the value of the pressure at the inlet, - p o represents the value of the pressure in the storage vessel, - p b represents a pressure having a predetermined value, and - Δ represents a predetermined pressure difference.