Online sampling density relay with protection function

The utility model discloses an on-line sampling density relay with a protection function, which comprises a main body shell arranged between an indicating dial and a connecting shell, a first external thread ring plate is fixedly connected to the edge position of one side, close to the main body shell, of the indicating dial, a first thread groove is formed in the side wall of the main body shell, and a second thread groove is formed in the side wall of the main body shell. And a second threaded groove is formed in the edge position of the side, close to the connecting shell, of the main body shell, a second outer threaded ring plate is fixedly connected to the side wall of the connecting shell, and an inner threaded pipe is fixedly connected to the middle position of the side, close to the connecting shell, of the main body shell. Compared with the prior art, the density relay has the advantages that a traditional integrated structure is replaced, the density relay has a convenient combination and installati