Floating fountains

Floating fountains

Site selection, buoyancy and stability design, bracing and operation in water areas

A floating fountain is a system whose weight of equipment is completely or mainly supported by floating objects. This set can be an independent pump and nozzle or a wide structure including several groups of water and light.

Its application in artificial lakes, urban ponds, water areas of parks and some reservoirs provides the possibility of creating water displays. In this method, the equipment can go up and down along with the change of water level; provided that bracing, cables and connections have the necessary range of motion.

In addition to hydraulics and electricity, the design of a floating fountain requires consideration of weight, buoyancy, stability, environmental forces, and access for service. The form of water maintains its desired quality when its floating bed behaves properly.

11–1. The difference between a floating fountain and a fixed fountain in a lake

Placing a fountain in a lake does not mean that it is floating. The equipment can be installed on fixed bases attached to the bed or on a floating structure.

Floating is not always the best choice. Shallow depth, the need for very precise positioning, extreme wave conditions or limited access may make another choice more appropriate.

In the introduction of GSO floating packages, the coordination with the change of water level and the preparation of the complex before deployment in the place are mentioned among the features of this method. Source: GSO city fountain floating packages ^[59]

11–2. Decorative fountain and ventilation system

Some floating fountains are designed for display, and some products target both display and aeration. These two functions must be evaluated separately.

Performance criteria include shape, height, splash width, readability from shore, and lighting quality. In the assessment of aeration, indicators such as oxygen transfer, water circulation and suitability of performance with water zone conditions are important.

The presence of a tall fountain or widespread spray alone does not prove that the oxygen demand or mixing of the entire lake is met.

Otterbine also introduces aerated fountains, surface aerators, circulators and deep aerators in different groups and refers to oxygen transfer and pumping test results to evaluate performance. Source: Otterbine Equipment Groups ^[60], Source: Equipment Performance Results ^[61]

If the improvement of water quality is one of the objectives of the contract, the measurable index, the evaluation conditions and the scope of the commitment should be specified. Selecting equipment based solely on water surface area or engine power is not sufficient for all areas.

11–3. Necessary information before design

The site impression should cover both display conditions and installation conditions.

The depth should be checked at the low water level. The proper distance between the pump inlet and the bed also depends on the device model, sediment and suction conditions.

The Otterbine selection guide considers depth, shape of the area, location and history of water quality problems as selection and placement factors. Source: Otterbine Selection and Sizing Guide ^[62]

11–4. Choosing the location and display scale

The placement of the fountain should be in harmony with the angle of view from the beach, the distance of the audience and the background.

An effect that is attractive from a distance may be seen from the other side of a small and less effective lake. On the other hand, increasing the height without checking the width of the spray and the wind can send water to the pavement, equipment or beach vegetation.

These limits should be specified in the initial plan:

• The nominal location of the collection;

• The permissible range of floating movement;

• Spraying range in operational conditions;

• Distance from the beach and other activities;

• Access path for installation and service.

For a multi-unit assembly, the distance between the units should take into account relative movement, cables and harness lines in addition to the visual composition.

Figure note from the source manuscript

Figure 1–11: Daytime wide view of an actual floating fountain in the GSO archive, showing the shoreline and scale of the lake. Suggested caption: "The placement of the floating fountain should be consistent with the viewing distance, splash range and operational access."

11–5. The main components of the floating complex

A set can include the following components:

The weight of all accessories must be included in the calculations. Adding a lamp, collector or cable after construction can change the balance of the assembly.

In integrated products, the shape and location of components may be determined by the manufacturer. For example, in the introduction of MIDI II, OASE introduces the float, pump, shield basket, and nozzle arrangements as components of an assembly. Changing this combination should be consistent with the limitations of the same product. Source: MIDI II floating fountain of OASE company ^[63]

11–6. Basic calculation of buoyancy

According to Archimedes principle, the buoyant force is equal to the displaced water weight:

Fᵦ = ρ × g × V

In this regard:

• Fᵦ: buoyancy force, Newton;

• ρ: water density, kg/m3;

• g: acceleration of gravity, meters per square second;

• V: Volume of displaced water, cubic meters.

For a set in static equilibrium, if only weight and vertical buoyancy force are considered:

V = m ÷ ρ

Let's assume that the total mass of the set, with the accessories included in the calculation, is 600 kg. Assuming the density of fresh water is 1000 kg/m3:

V = 600 ÷ 1000 = 0.6 cubic meters

Therefore, for static equilibrium, the complex must displace 0.6 cubic meters of water.

This number is not the final required volume of the vessels. Buoyancy reserve volume, free height, stability, operating forces and loading modes should also be considered.

Also, the nominal volume of an open tank or container into which water enters is not necessarily the effective volume of buoyancy. The calculation should be based on the geometry and sections that actually move the water.

11–7. Water trough, free height and overload effect

The sinkhole is defined as the depth of the collection in relation to a specific reference. Free height is also the vertical distance of the water surface to the edge or reference point defined on the structure.

If the cross-sectional area of the collection at the point of contact with the water level is almost constant within the range of changes, the rise of the water intake can be calculated initially:

ΔT ≈ Δm ÷ (ρ × Awp)

In this regard, Awp is the cross-sectional area at the level of the water level; Not necessarily the total area of ​​the chassis in the top view.

Suppose:

• Added mass: 100 kg;

• Cross-sectional area at water level: 3 square meters;

• Density of water: 1000 kg/m3.

Then:

ΔT ≈ 100 ÷ (1000 × 3) = 0.033 m

That is, the increase of the water intake will be approximately 3.3 cm.

This example assumes a symmetric added load and a small change in the aquifer. If the same load is placed on one side, tilting also occurs and this relationship alone is not sufficient. The concepts of displacement, water surface cross-section and stability in the engineering resources of vessels are examined separately. Source: USNA Naval Architecture Teaching Notes ^[64]

Figure note from the source manuscript

Figure 2-11: Floating training section in two states of initial load and symmetrical added load; By displaying the water level, water inlet, free height and displacement volume. Suggested caption: "Increasing weight changes ensemble balance; Sufficient buoyancy should be checked along with stability.

11–8. sustainability; The ability to return from a tilted state

A set may stay afloat, but not behave well against tilting.

Stability depends on the geometry of floats, weight distribution, position of the center of mass and the change in the location of the effect of the buoyancy force when tilting. Placing heavy equipment at a high height or accumulating weight on one side can change the behavior of the set.

The important modes of investigation are:

• Asymmetrical distribution of pumps, lights and collectors;

• cable tension or harness line;

• Forces caused by operation and changing effects;

• wind, wave and current;

• Infiltration of water to the damaged part;

• Service load, only if the presence of repairman on the structure is allowed in the design.

A floating fountain is not necessarily a walkable platform. If the complex is not designed for human presence, the method of service must be based on other perception or access.

The sustainability criterion should cover both the safety of the structure and the quality of the display. A tilt that is tolerated for hovering may cause unfavorable jet direction and light symmetry.

11–9. Bracing design

The bracing should keep the position and direction of the assembly within the permissible limits and at the same time allow the necessary movement with the change of the water level.

This system can be connected to bed restraints, shore points or a combination of them. The selection of the method depends on the depth, material of the bed, waterproof cover, level change range and environmental forces.

In the design, the length and angle of the lines, their materials and resistance, connections, containment capacity and the possibility of inspection should be specified. The weight of a containment block in air alone does not indicate its resistance to sliding or lifting underwater.

Kasco's installation instructions also specifically address bracing and water level changes; Its details are for models of the same guide and should not be generalized to other structures without investigation. Source: Kasco J Series floating fountain installation guide ^[65]

For a lake with a waterproof cover, the method of deploying the containment should prevent damage to the cover. The route of the lines should also be coordinated with the cables and possible activities on the water.

Figure note from the source manuscript

Figure 3-11: Schematic plan and section of bracing at low, normal and above water level. The power cable should be displayed with a different symbol than the harness lines. Suggested subtitle: "The embankment must accommodate the change in water level and keep the horizontal displacement within the design limits." The dimensions and number of restraints in the picture are not prescribed.

11–10. Suction, nozzle and inlet water quality

In many floating fountains, water is taken directly from the surrounding area. Therefore, leaves, plants, sediment and floating materials can affect the yield.

The choice of strainer should be compatible with flow rate, allowable pressure drop and cleaning access. Clogging of the inlet can change the height or shape of the effect and make the working conditions of the pump unsuitable.

Fine path nozzles may require cleaner water and tighter inlet protection. The suitability of the nozzle with the water quality should be checked before purchase.

The minimum working depth, distance from the bed and immersion conditions should be extracted from the documents of the selected model. Seasonal lowering of level or accumulation of sediment may alter initial installation conditions.

Also, the water collected from the lake should be checked for suitability with the type of spraying and the distance from people; The use of available water does not in itself mean that it is suitable for direct contact.

11–11. Power supply, cable and control

In addition to the electrical requirements, the floating fountain cable faces movement and mechanical forces.

The design should specify the following:

• The type of cable and connections suitable for installation conditions;

• voltage drop and current capacity in the real path;

• electrical protection and isolation method for service;

• Inhibition of traction at the entrance of the equipment;

• The length necessary to change the level and allow displacement;

• Protection against abrasion, snagging and water activities.

The power cable should not act as a harness line or a means of pulling the assembly. Kasco's guide also emphasizes on preventing the device from being moved by cable and using tension restraints. Source: Kasco Installation and Maintenance Manual

In systems with wireless communication, the behavior when the connection is lost must be known. The existence of remote communication is not a substitute for local protections and equipment status control.

The location of the coastal sign should also be chosen in accordance with the risk of flooding, public access and the possibility of service.

11–12. Lighting and night show quality

The lighting of the floating fountain should make the shape of the water visible from the main viewing points. The angle of the light, its distance from the stream, color, intensity and background are all important.

The floating motion can change the direction of the light. Therefore, the place of lights and bases should be chosen along with checking the stability.

It is also necessary:

• Direct glare towards the beach should be controlled;

• Check the permitted working condition of the lamp at different depths;

• The weight of the lamp and cable should be included in the calculations;

• Provide access for cleaning and adjustment.

The reflection of light on the water surface can be part of the visual composition, but a night test in the actual location is necessary to evaluate the result.

11–13. A documented example of GSO activity

On the GSO floating packages page, the musical fountain project of Mellat Park in Tehran has been introduced. The included scope of work includes the design and installation of lighting, reconstruction and repair of the mechanical equipment of the floating package and control and electrical systems. Source: Project introduction on GSO website

This example provides a suitable context for explaining the restoration of floating fountains in the book: the existing project can be reviewed in terms of the condition of the structure, equipment, lighting and control and modified for continued operation.

To provide a complete case study, information such as year of work, dimensions, pre- and post-renovation equipment, and test results should be extracted from the project file. The title and description of the images should also be compatible with the scope of the document.

Figure note from the source manuscript

Figure 4-11: Day and night images of Mellat Park project from GSO certified archive; If available, a picture of the restoration operation should also be added. Proposed subtitle: "Renovation of the mechanical equipment, control, electricity and lighting of the Mellat Park fountain floating package; According to the service description of the project document.

11–14. Installation, service and seasonal shutdown

The installation method should be determined before construction: where does the assembly enter the water, how is it transported to the site, and what route does it return for repair?

The plan should specify the lifting weight, the permitted lifting points, the handling equipment and the working location on the shore. Installation and service on water also requires a working method suitable to the conditions of the place and a trained team.

In periodic maintenance, these things are important:

• Cleaning the inlet and nozzles;

• Inspection of vessels in terms of water damage or penetration;

• Chassis and connection corrosion control;

• Revision of harness lines and cables;

• Comparing the alignment, skewness and quality of the effect with the delivery status;

• Checking protections and recording equipment errors.

The winter program should be in accordance with the climatic conditions and the manufacturer's order. Removal of the device or other measures may be necessary; Turning it off alone will not remove all effects of freezing and changing zone conditions.

11–15. Project testing and delivery

The delivery criteria should cover both display and floating behavior.

The limits of wind, wave, water level and other permitted operating conditions should be clear in the project documents. A successful test on a calm day alone does not prove performance in all environmental conditions.

A floating fountain can turn a water area into a prominent part of the city landscape. The durability of this experience depends on the coordination of the show with the behavior of the structure, lake conditions and maintenance facilities.

In Chapter 12, waterfall, curtain, and channel fountains are explored; From the formation of the layer and the path of the water to the selection of the drop edge, splash control and coordination with the architecture.