Product category:
Process Hardware (Pipes, Nozzles, Heaters, etc)
News Release from: Rotork Controls | Subject: EH actuators
Edited by the Engineeringtalk Editorial
Team on 09 March 2006
Valve actuators in water treatment
upgrade
Installation of actuators prevents re-occurrence of potentially serious contamination problem at water treatment plant caused by hydraulic oil spillage.
A recent upgrade project at the Hap Cremean water treatment plant, serving the city of Columbus in Ohio, USA, involved the installation of Rotork's EH electro-hydraulic range of heavy-duty valve actuators to prevent the re-occurrence of a potentially serious contamination problem caused by hydraulic oil spillage The plant provides an average 265 million litres of water per day, using six high service pumps, each with a 76 million litre a day capacity to deliver the water
This article was originally published on Engineeringtalk on 17 Mar 2000 at 8.00am (UK)
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Each pump is fitted with a 76cm ball valve that must be closed in the event of a pump failure to prevent the water from back-flowing into the treatment works.
These valves were originally equipped with linear hydraulic cylinders and quarter-turn linkages, all six of which were powered by a central hydraulic power unit located some distance from the valves on a lower floor.
A leak from the hydraulic circuit resulted in 190-litre of the 3785-litre oil system escaping and flooding the surrounding floor space.
Apart from the obvious mess and inconvenience, the oil also presented a potentially serious risk of contamination to the water treatment plant.
Not wishing to be faced with this problem again, the plant's operators decided to replace the entire existing hydraulic system and chose Rotork EH actuators for the upgrade.
Unlike conventional hydraulic actuators, the EH is a stand-alone design comprising a fully enclosed power unit containing an electric motor, hydraulic pump and reservoir.
Combining the speed and accuracy of hydraulic positioning with the convenience of electrical operation, the EH also provides the benefits of simplified remote control and indication associated with electrical actuators.
A feature of the integral controls is the ability to adjust the speed of valve travel to meet precisely important operating criteria (for example, maximum speed without inducing water-hammer), without resorting to conventional hydraulic flow control valves.
The actuator also eliminates the ongoing operating and maintenance costs associated with traditional central hydraulic power units.
As an added benefit at Hap Cremean, because each actuator requires only a few litres of hydraulic oil, it was economically feasible to use a food grade variant which presents no risk of contamination in the unlikely event of a leak.
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