Ondernozzle

Ondernozzle is a term used in engineering to describe a nozzle system designed to deliver a fluid jet to surfaces located beneath a structure, most commonly in underwater contexts. The concept is applied in subsea maintenance and offshore operations to clean, coat, or cool undersides of hulls, platforms, or submerged equipment without full access to the surface.

The name combines onder, the Dutch word for under, with nozzle, reflecting its orientation and typical application. In practice, ondernozzles are regarded as directional or multi-jet devices that can be mounted on remotely operated vehicles (ROVs), diver-operated platforms, or fixed hull frames.

Designs vary, but common configurations include single-jet and multi-jet arrays with adjustable spray angles. Materials are chosen for corrosion resistance, such as stainless steel or titanium. Some variants use coaxial arrangements to mix cleaning fluids with rinse streams, while others employ separate spray channels. Control options range from manual to fully automated, with hydraulic or electric actuation and integrated sensors for flow, pressure, and nozzle blockage.

Operating use cases include underwater hull cleaning to remove biofouling, coating or re-coating of submerged surfaces, and cleaning or cooling of subsea equipment like manifolds and pipelines. The technology emphasizes precise targeting of the undersurface while reducing the need for extensive scuba or ROV maneuvering.

Advantages include localized treatment of hard-to-reach areas and reduced exposure for divers. Challenges involve corrosion, clogging, fouling of the nozzle, and the need for accurate positioning and reliable power and control systems.