Directly buried compensators can be divided into two types according to the way they bear pressure: internal pressure type and external pressure type. Both types of compensators differ in design, working principles, and application scenarios. Here are their main differences:
Internal pressure directly buried compensator
Source of pressure: The pressure bearing by the internal pressure compensator comes from the pressure of the medium inside the pipe, that is, the medium pressure acts on the inside of the bellows.
Working Principle: When the temperature of the medium inside the pipe increases, the pipe elongates due to thermal expansion. The internal pressure compensator absorbs this part of the expansion through the compression of its bellows, thereby relieving the stress on the pipe.
Installation Requirements: Before installation, internal pressure compensators usually need to be pre-stretched according to the ambient temperature to accommodate the thermal expansion of the pipe.
Observation and maintenance: The bellows of the internal pressure compensator can be observed in the working state, which is convenient for inspection and maintenance.
Cost and applicable scenarios: Internal pressure compensators are usually less expensive and suitable for general directly buried pipeline systems.
External pressure directly buried compensator
Source of stress: The external pressure compensator is subjected to pressure from the outside of the pipe, usually external pressure on the outside of the bellows, such as soil pressure or external mechanical load.
How it works: The external pressure compensator absorbs the thermal expansion of the pipe through the stretching of its bellows. When the pipe is elongated due to an increase in the temperature of the medium inside the pipe, the bellows stretches outward, thereby counteracting the expansion of the pipe.
Installation Requirements: The external pressure type compensator needs to be pre-compressed according to the ambient temperature before installation, which is the opposite process of the internal pressure type.
Observation and maintenance: The bellows of the external pressure compensator are not easy to observe in working condition because the outside of the bellows is subjected to pressure, which means that maintenance and inspection can be complicated.
Cost and applicable scenarios: External pressure compensators are usually expensive, and are suitable for directly buried pipeline systems that need to withstand external pressure or have special working conditions.
Summary
Installation and Operation: The operation process of the internal pressure type and the external pressure type compensator is different during installation. The internal pressure type needs pre-stretching, while the external pressure type needs pre-compression.
Safety Considerations: If the working steel pipe of the internal pressure compensator is opened, it will cause media leakage; However, if the bellows of the external pressure compensator is damaged, it may not be visually found until serious problems occur.
Price difference Other: External pressure compensators are generally more expensive than internal pressure compensators, possibly due to their more complex design or the use of higher grade materials.
When selecting a directly buried compensator, it is necessary to decide whether to use an internal pressure or external pressure compensator according to the specific working conditions of the pipeline (such as internal pressure, external load, temperature change, etc.) and cost budget. The correct selection and installation of the compensator is essential to ensure the safe operation of the plumbing system.