A valve injector (10) comprising: a body (12) defining a fluid conduit (14), the fluid conduit (14) accommodating first, second and third checks (16, 18, 20), the first check (16) being disposed within the fluid conduit (14) towards a first end (10a) of the injector (10), the second check (18) being disposed towards a second end (10b) of the injector (10), distally from the first end (10a), and the third check (20) being located between said first and second check (16, 18).