Products

Extraction Stop Valves for Tapping

Extraction stop valves are fitted in extraction steam pipelines leading to turbines.
During load tripping, they protect the turbines against undue increases in rotation speed caused by the energy accumulated in the pre-heaters and the extraction steam lines.
In this way, hot components are protected from thermal shock.

Range of Applications for Model A

The extraction stop valve is designed as non-return valve with an additional actuator-induced safety function. A spring energy cylinder can hold the valve closed against a pressure differential, depending on the system parameters (Δp). The spring in the cylinder is tensioned by means of hydraulic oil when the turbine is started, whereby the adjusting cam rotates away from the sealing element in such a way that the full stroke of the valve is deblocked. The valve opens to its full stroke automatically as soon as a pressure differential arises in the opening direction of the valve plate. Conversely, this means that the valve closes before the direction of flow is reversed.

Further Advantages

BOMAFA’s extraction stop valves have a streamlined valve interior. By thus ensuring that the medium is properly channelled we are able to assure uninterupted operation for long periods, even with high through-put.
The valve bodies are engineered from creep-resistant cast steel. The channels of the valve plates are surface heat-treated. The sealing elements and plates are engineered from non-corroding and highly wear-resistant high-grade steel and hardfaced according to BOMAFA’s own special technique.
The actuating drives are housed in a bracket which is firmly anchored to the valve body. Due to its double-sided construction it is possible to mount the actuator on the right or the left, viewed in the direction of flow.

Range of Applications for Model B

If double safeguarding against reverse flow of steam is required, BOMAFA can retrofit the valve with a second spring-operated valve plate.