Actuation on gas transmission pipelines
Gas / Hydraulic actuators are most normally used for automating valves located in gas transmission pipelines.
These pipelines typically run hundreds of miles through inhospitable and undeveloped areas where no low pressure pneumatic instrument air or high pressure hydraulic supply lines are available.
Since pipelines carry gas under high pressure, is this supply the potential source for the gas / hydraulic actuators.
Because of that the pressurized gas is an explosion source, prevents the oil barrier the safe operation of the actuator unit.
The pipeline medium gas which will be used to operate the unit, can be taken direct from pipeline and can be applied to the actuator unit.
A tap of the gas can occur upstream and downstream from the pipeline, nevertheless it must be ensured that the highest gas pressure will be used to power the actuator unit.
Resultant from that is the gas supply pressure at the actuator unit always equal or greater than the differential pressure at the valve.
Actuator key features
The stainless steel and lockable cabinet is designed that all components are well protected against the ingress of foreign bodies.
Furthermore provided the enclosure the operation under severe climatic conditions as well as defence against unattended and non authorized operation and vandalism.
Through the modified back up plate of the cabinet, is a proper operation of the integrated handpump in the system guaranteed.
All items which vent will have common exhaust port outside of the cabinet.
Vents from gas-hydraulic system will vent vertically upwards at a minimum high of 0,5 m above the top of the cabinet. Such vent pipe shall be fitted with vent flaps to prevent the ingress of dirt.
Due to the modular construction of our system, is it possible to replace control parts from the system at open cabinet door. Also the pipework is reduced through the construction on a minimum.
A provided switch for the cabinet provides the electrical interlocking, so that the control system can be operated only by local personnel.
A remote control by the control room is therefore not possible to ensure the safety of the staff.
Flow restrictor valves can be used independently for both directions to adjust the opening and closing time.
For low temperature application, the control system can be equipped with an explosion proof heating system if required.
Gas over Oil Standard Control System
All Gas over Oil actuators will be supplied as standard with a control system, which
enable to open and close the valve by using the gas from pipeline (sour gas application excluded).
A manual hydraulic handpump is optional available.
Through the standardized modular design are leaking points minimized, what improves the reliability of the control system additionally.