Why do we use flexible waterproof casing for fire fighting pools?

Waterproof casing for wells is used in the construction of water wells, where there is a high waterproof requirement for the pipeline through the wall.
The flexible waterproof casing is sealed with flexible material between the well casing and the pipe. Rigid waterproof casing, is the well with a waterproof casing and pipe between the rigid material blocking to achieve sealing effect.
Waterproof casing for fire fighting pools can be used with flexible waterproof casing. Because the device contains a certain degree of prevention of water seepage, flow, flow to the lower layer of the role of the "prevent" here is said to have two aspects: on the one hand, refers to the completion of the project, the user in the renovation phase, improper reasons, resulting in the flow of tap water, flow through the casing lower layer; on the other hand, after the user moved in, accidental reasons, resulting in the flow of tap water, flow through the Casing flow under the layer, and the former is often more than the latter.
Rigid waterproof sleeve over the pipe or other cables, etc., you need to use other sealing materials such as oil hemp stuffed into the gap to plug the leak, poor sealing, can not be used in places with high sealing requirements.
Flexible waterproof casing with its own airtight wing ring and protective resistance piece, in the pipeline through the airtight partition wall, should be treated with caution, do not allow the use of pre-drilled holes, otherwise the fortification will be scrapped;
The operation specification has strict requirements for the height of the flexible waterproof casing: in rooms with water, the height of the flexible waterproof casing should be 50 mm above the living ground, the flexible waterproof casing of the plastic water supply pipe should be more than 100 mm above the ground. And should be sealed tightly with oil paste.