Closed reaction tube

The embodiment of the utility model provides a closed reaction tube is related to, include: the reaction tube body is the cylinder tubulose, has first external screw thread on the outer wall of top, gu fixed ring has connecting portion and holding portion, a connecting portion top surface and a holding portion bottom surface body coupling, connecting portion are the ring -type, and the centre has first through -hole, and the pore wall has first internal thread, through first external screw thread and first interior thread screwed connection between reaction tube body and the solid fixed ring, holding portion is cylindricly, and the top surface has first circular recess, and the bottom surface has the second through -hole, and the surface has the second external screw thread, the silica gel pad, diameter and the diameter phase -match of first circular recess and the degree of depth phase -match of thickness and first circular recess, the upper cover is cylindric, and the top surface has a plurality of contact