An alternative to conventional water drainage systems
Floating roof tanks offer several advantages over fixed roof tanks; however, a common pain point users must face is failure as a result of rainwater accumulation. Here Application Specialist – Pumps at Crane ChemPharma & Energy, Thomas Walbroehl, discusses one solution.
When floating roof tanks are in place, it is important that adequate drainage systems are installed to remove the buildup of rainwater before it builds to a heavy load. Whilst conventional systems consist of hinged draining pipes which operate solely on gravity, a more efficient system features an AODD (Air Operated Double Diaphragm) pump, offering numerous advantages beyond rainwater drainage.
When draining water from floating roof tanks, AODD pumps don’t have to rely on gravity to remove the water, they use sufficient pressure to drain and transfer the water, preventing the hoses or pipes from clogging and overgrowing. Equipped with a mechanical fluid level control, the pump can operate autonomously, consuming air once a certain water level has been reached within the collecting basin which triggers the pump to operate. That level control can be installed beside or mounted to the pump, allowing an adequate hose installation for air supply, discharge and suction.
An added benefit of using AODD pumps in drainage systems is the serviceability of installation. Unlike conventional systems that have fault-prone and complex pipe systems inside the tank that cannot be easily accessed for regular or even spontaneous servicing, AODD pumps are easily accessible for regular maintenance. Lightweight and compact in size, the AODD pump can be placed on the rooftop without adding much weight or taking up a lot of space.
AODD pumps can also be used in high-risk atmospheres (e.g. petrochemical tanks). In such facilities, the area above the floating roof is generally declared the most critical ATEX zone 0, which limits the installation of certain equipment that could prove flammable. However, AODD pumps are specifically certified for such areas, as they can operate without any electrical source, and the fluid level control fulfills the requirements for this zone, unlike other pumps that require an electrical source and feature level monitoring sensors.
In summary, the AODD pump offers an efficient draining solution for floating roof tanks. Its size and easy install features eliminate the need to overhaul a system installation in order to clean and conduct routine maintenance, as is needed with conventional drainage systems. This equates to labor, material and cost savings, while protecting tank components.
Crane Co. is traded on the New York Stock Exchange (NYSE:CR). Crane ChemPharma & Energy (within Crane’s Fluid Handling segment) designs and manufactures a variety of high performance products including: highly engineered check valves, sleeved plug valves, lined valves, process ball valves, high performance butterfly valves, bellows sealed globe valves, aseptic and industrial diaphragm valves, multi/ quarter-turn valves, actuation, sight glasses, lined pipe, fittings and hoses, and air operated double diaphragm and peristaltic pumps.
Picture caption: Installation of an AODD pump with external fluid level control in an ATEX Zone 0
5th June 2017