Safety valve , having: a valve body with a guide bore defining a longitudinal axis (L1), a first opening formed at a bottom of the guide bore , and a second opening which is spaced apart from the bottom along the longitudinal axis (L1) and extends along a radial direction (R1) extending transversely to the longitudinal axis (L1); a valve needle axially displaceably mounted in the guide bore of the valve body with a sealing surface facing the first opening ; a compression spring device with a spring which is compressed by a preloading path (V) and thereby preloads the valve needle along the longitudinal axis (L1) into a sealing position, in which the sealing surface of the valve needle seals the first opening ; and a thermally activatable release unit , which has an extent (I4) along the longitudinal axis (L1) which is greater than the preloading path (V) and which is designed to collapse when a release temperature is reached, wherein the compression spring device is supported against the release unit , characterized in that a locking device with a locking body which is mounted displaceably in a locking recess of the valve body extending in the radial direction (R1) and a spring which preloads the locking body in the radial direction (R1) towards the longitudinal axis (L1); wherein the second opening of the valve body is arranged with respect to the longitudinal axis (L1) between the locking recess and the bottom ; and wherein the valve needle has a locking groove which, in a sealing position of the valve needle , is positioned between the locking recess and the bottom of the valve body at a predetermined distance from the locking recess , and wherein the locking body engages in the locking groove in a locking position, in which it protrudes into the guide bore when the valve needle is pulled back by the predetermined distance from the first opening . a valve body with a guide bore defining a longitudinal axis (L1), a first opening formed at a bottom of the guide bore , and a second opening which is spaced apart from the bottom along the longitudinal axis (L1) and extends along a radial direction (R1) extending transversely to the longitudinal axis (L1); a valve needle axially displaceably mounted in the guide bore of the valve body with a sealing surface facing the first opening ; a compression spring device with a spring which is compressed by a preloading path (V) and thereby preloads the valve needle along the longitudinal axis (L1) into a sealing position, in which the sealing surface of the valve needle seals the first opening ; and a thermally activatable release unit , which has an extent (I4) along the longitudinal axis (L1) which is greater than the preloading path (V) and which is designed to collapse when a release temperature is reached, wherein the compression spring device is supported against the release unit , characterized in that a locking device with a locking body which is mounted displaceably in a locking recess of the valve body extending in the radial direction (R1) and a spring which preloads the locking body in the radial direction (R1) towards the longitudinal axis (L1); wherein the second opening of the valve body is arranged with respect to the longitudinal axis (L1) between the locking recess and the bottom ; and wherein the valve needle has a locking groove which, in a sealing position of the valve needle , is positioned between the locking recess and the bottom of the valve body at a predetermined distance from the locking recess , and wherein the locking body engages in the locking groove in a locking position, in which it protrudes into the guide bore when the valve needle is pulled back by the predetermined distance from the first opening . <EOS>