Solid particles-fluid separator, optionally for liquid, comprising: - a containment body extending along a longitudinal axis between a top portion and a bottom portion (2a, 2b) and defining a housing compartment, said containment body comprising at least one through access configured for allowing the in and/or out passage of fluid from the containment body, - a magnetic device at least partly arranged in the housing compartment and at least partially facing the access, wherein the magnetic device extends for a preponderant part of the containment body along the longitudinal axis, said magnetic device being configured for attracting ferrous or ferromagnetic particles present in the fluid, wherein the magnetic device comprises: ∘ a casing having elongated shape and extending between a first end portion, at which the casing is engaged to the containment body, and a second end portion, ∘ at least one magnet housed in the casing, wherein the containment body also comprises a discharge opening configured for allowing the discharge of solid particles from the separator, wherein the separator also comprises a shutter carried by the casing and movable relative to the containment body, at least between: - a first operating position in which the shutter prevents the passage of fluid through the discharge opening, and - a second operating position in which the shutter allows the passage of fluid through the discharge opening, wherein the casing comprises a hollow body defining a compartment within which the magnet is housed, the hollow body of the casing having: - a first passage opening placed at the first end portion of the casing and through which the magnet can be removed from or inserted into the casing, wherein the magnetic device comprises a closure element engageable with the containment body and placed to close the first passage opening of the casing, characterized by the fact that the hollow body of the casing has a second passage opening placed at the second end portion of the casing in communication with the first passage opening, the shutter is engaged at the second end portion of the casing and placed to close the second passage opening, the casing, the closure element and the shutter delimit a closed volume compartment for the magnet. - a containment body extending along a longitudinal axis between a top portion and a bottom portion (2a, 2b) and defining a housing compartment, said containment body comprising at least one through access configured for allowing the in and/or out passage of fluid from the containment body, - a magnetic device at least partly arranged in the housing compartment and at least partially facing the access, wherein the magnetic device extends for a preponderant part of the containment body along the longitudinal axis, said magnetic device being configured for attracting ferrous or ferromagnetic particles present in the fluid, wherein the magnetic device comprises: ∘ a casing having elongated shape and extending between a first end portion, at which the casing is engaged to the containment body, and a second end portion, ∘ at least one magnet housed in the casing, ∘ a casing having elongated shape and extending between a first end portion, at which the casing is engaged to the containment body, and a second end portion, ∘ at least one magnet housed in the casing, wherein the containment body also comprises a discharge opening configured for allowing the discharge of solid particles from the separator, wherein the separator also comprises a shutter carried by the casing and movable relative to the containment body, at least between: - a first operating position in which the shutter prevents the passage of fluid through the discharge opening, and - a second operating position in which the shutter allows the passage of fluid through the discharge opening, - a first operating position in which the shutter prevents the passage of fluid through the discharge opening, and - a second operating position in which the shutter allows the passage of fluid through the discharge opening, wherein the casing comprises a hollow body defining a compartment within which the magnet is housed, the hollow body of the casing having: - a first passage opening placed at the first end portion of the casing and through which the magnet can be removed from or inserted into the casing, wherein the magnetic device comprises a closure element engageable with the containment body and placed to close the first passage opening of the casing, - a first passage opening placed at the first end portion of the casing and through which the magnet can be removed from or inserted into the casing, wherein the magnetic device comprises a closure element engageable with the containment body and placed to close the first passage opening of the casing, characterized by the fact that the hollow body of the casing has a second passage opening placed at the second end portion of the casing in communication with the first passage opening, the shutter is engaged at the second end portion of the casing and placed to close the second passage opening, the casing, the closure element and the shutter delimit a closed volume compartment for the magnet.