Nozzles and selection principles

Nozzles and selection principles

Knowing the shape of the flow, reading the technical specifications and adapting the nozzle to the project

The nozzle is the last part that shapes the flow of water before it enters the display space. The energy provided by the pump and the network is converted into a narrow jet, air-sucking column, continuous curtain, transparent arc or a collection of droplets in the nozzle.

Nozzle selection affects architecture, energy consumption, spray range, lighting, sound and maintenance. For this reason, it is not enough to choose based solely on the catalog image or the declared maximum height.

In the previous discussions, the calculation of flow rate and head was examined. This chapter explains how nozzle information is read and how to make a defensible choice among different options.

21–1. Nozzle selection begins with defining the effect

Before determining the model, the expected image must be clear:

• Is the flow clear or bulky and air-consuming?

• Does the water move vertically, obliquely or in an arc?

• Is the effect constant or does it change during the show?

• Does the audience see it up close or from a distance?

• Direct contact of people with water is foreseen or just watching?

• What range should there be for receiving water?

For example, the phrase "three-meter fountain" is not a complete specification. A three-meter narrow jet and a three-meter massive column can have different flow rate, pressure, sound and spray range.

A more appropriate definition could be:

"Relatively transparent vertical jet, with a target height of three meters from the nozzle opening, visible from the main path, with the possibility of height reduction in windy conditions."

This definition is the starting point for product review.

21–2. Classification of nozzles based on the shape of water

Brand names are not the same among manufacturers. The following table is the descriptive classification of this book and should be matched with the exact model of the product in each purchase.

In the list of GSO products, families such as Comet, Cascade, Foam, Fan, Paw, Chatri, Dandelion and Laminar have been introduced. The characteristics of each family should be extracted from the information of the selected model. Types of urban fountain nozzles GSO ^[123]

Figure note from the source manuscript

Figure 1–21: Comparison screen of six realistic effects including comet, cascade, fan, claw, umbrella, and laminar. The photos are selected from the company's archive and the names of the models are inserted after matching. Suggested caption: "Nozzles transform water flow into shapes with different technical needs and visual experience."

21–3. Comet nozzle and cluster jets

Comet nozzle is used to create a specific and relatively transparent jet. Its output quality depends on internal design, inlet flow condition, orifice cleanliness and direction setting.

In the introduction of the GSO steel comet nozzle, the flow turbulence reduction piece and the ball joint for angle adjustment are mentioned. These features should be checked in the selected model and installation plan. Comet steel GSO nozzle ^[124]

The presence of an adjustable connection does not mean a programmable movement. Manually adjusting the angle during installation is different from automatically changing the orientation during the display.

In cluster jets, several exits next to each other create a larger volume. The number of outputs, their distance and the shape of the currents are important. Do not estimate the flow rate or the final diameter of the water column based only on the diameter of the inlet connection.

21–4. Air intake, foam and cascade nozzles

In this group, air entrainment can create a whiter and bulkier appearance. The visual volume of water and air is not the same as the actual flow rate of pumped water; The selection of the pump should be based on the declared water flow rate.

The working conditions of the members of this family are different. For example, GSO explains about the cascade nozzle that changing the water level affects the thickness and height of the effect. OASE has also specified water level dependence for Cascade 70 T. Cascade GSO ^[125], Cascade 70 T from OASE ^[126]

The name "foam" alone does not determine the installation conditions. For example, Crystal Fountains introduces the NFO family as dependent on the water level; This feature should be checked for the desired model. NFO foam nozzle ^[127]

In choosing this group, the location of air suction, installation height and the effect of pond waves should be checked. Blocking or improperly submerging the air intake can alter the effect.

21–5. Sheet, fan and laminar effects

In laminar effects, the quality of the exit edge, flow distribution and environmental conditions affect water continuity. A beautiful shape in a short specimen does not prove similar performance in a longer one; Water distribution should be checked for final dimensions.

A fan nozzle and a finger nozzle also look different: a fan spreads water in a plane; A finger creates several separate strands. This difference is effective in the choice of light, background and place of receiving water.

The laminar nozzle is designed to create a flow with a smooth and glassy appearance. In this application, the condition of the incoming current and the cleanliness of the internal components are of particular importance. GSO mentions the need for a disc filter for the laminar model introduced on the site. The type and degree of filtration must be specified for the same product. GSO laminar nozzle ^[128]

The "jumping jet" effect is dependent on the ability to create separate stream segments. Every laminar nozzle does not necessarily have this capability. Crystal also introduces Laminar and Leaper with continuous and jump effect. Crystal Fountains laminar and jumping effects ^[129]

21–6. Nozzle shape, control method and installation type

Three features must be specified separately:

Output shape: comet, foam, fan and so on.

Control method: fixed, connect and disconnect, change height or change direction.

Type of installation: inside the pond, embedded in the floor, on the structure or in the floating complex.

For example, a Comet jet may be activated by an on-off valve, raised by changing pump speed, or mounted on a multi-axis actuator. These capabilities are obtained from the entire system.

In the introduction of SWS, Crystal separates the programmable on-off function from the height change with a variable-speed pump. OASE also offers multi-axis actuators to move compatible nozzles. SWS control nozzle ^[130], OASE multi-axis actuator ^[131]

Also, "dry floor" describes the type of installation. Suitability of the complex for people contact, vehicle passing or interactive activity should be verified separately.

21–7. Dependence on water level

The nozzle dependent on the water level must be installed in a specific position relative to the water level. Changing this ratio can change the height, shape or amount of air mixing.

In the specifications of some nozzles, it is mentioned that the operation is independent of the water level. This phrase should also be interpreted within the limits and conditions of the installation; It cannot be concluded that the nozzle will perform the same at any depth or with any immersion condition.

These levels should be clear in the design:

• The usual operating balance;

• The minimum and maximum allowed balance;

• position of the opening and air inlets;

• wave amplitude or local oscillation;

• Water condition after blackout.

For sensitive nozzles, the constant average water level in the entire pond is not enough; There may be a local ripple or drop around the nozzle.

Figure note from the source manuscript

Figure 2–21: Three training sections of a level-dependent nozzle, at lower level, recommended level, and higher level. The change of shape of water should be shown schematically. Suggested caption: "Mounting alignment is part of the nozzle performance specification." Shapes are adapted to the data of the selected model.

21–8. How to read the technical sheet of the nozzle?

The appropriate technical data sheet should allow for matching performance and installation.

Units are not the same in different catalogs. For example, GPM should be specified in US or imperial gallons. Also, the joint size is not necessarily the inner diameter of the track or the diameter of the jet.

Maximum numbers may belong to different models of the same family. The highest height, the lowest flow and the smallest family size should not be put together as the specifications of a single product.

21–9. Educational example of reading performance table

The table below is made for training and is not a specification of any actual product. We assume that the height is measured from the nozzle opening and the static pressure head at the inlet connection.

For a three-meter effect, a flow rate of 30 liters per minute and a pressure head of 8 meters must be provided at the nozzle entrance.

A pressure head of 8 meters, for water with an approximate density of 1000 kg/m3, is approximately equal to:

$p=\rho gH$

$p=1000\times 9.81\times 8=78,480Pa\approx 0.785bar$

If 12 nozzles are active at the same time:

$Q_{total}=12\times 30=360L/min$

$Q_{total}=21.6m^3/h$

These numbers are consistent with the example entry in Chapter 20. To select the pump, the level difference and path drop are also checked according to the method of that chapter.

A few misconceptions about the table should be discarded:

• The pump head cannot be selected only three meters, equal to the height of the effect.

• The three-meter height should not be added to the eight-meter pressure head of the nozzle.

• Adequate pressure with insufficient flow rate does not satisfy the performance conditions of the table.

• Cannot predict performance with confidence outside of table range.

Interpolation between points can also be checked for initial selection; Near performance limits or at sensitive effects, manufacturer approval or testing will be required.

21–10. Wind and water intake range

Wind resistance is a relative characteristic. Even a nozzle that creates a consistent jet will not land the water in the same place at any height and any wind speed.

To choose, the shape of the flow, height, duration of presence of water in the air, wind direction and distance to the edge of the pond should be checked. Streams of droplets and thin sheets also need to be evaluated according to their shape.

In addition to the main flow path, the water intake area should cover the impact splash and operational changes. Determining a constant ratio between the height of the fountain and the width of the basin is not suitable for all nozzles.

In controllable systems, it is possible to predict the gradual reduction of the height or the stopping of some groups. For example, Crystal's ECW sensor has been introduced to adjust fountain performance according to wind speed. ECW wind control system ^[132]

Control thresholds should be determined for the actual site and effect. Installing a wind sensor is not a substitute for choosing the right nozzle and basin.

21–11. Water quality and nozzle material

The quality of water affects both the durability of the product and the shape of the output. Particles, sediment, and contamination can affect the orifice, strainer, or flow forming components.

The large opening does not mean that the system does not need purification. A distinction must be made between preventing clogging of the nozzle, preserving the appearance of the water, and user hygiene requirements.

The general title "steel" is not enough in choosing the material. Grade, build quality, water conditions and compatibility of connected parts should be checked. For brass, bronze and polymer materials, the specifications of the same product and its environmental limitations should be the criterion.

If the nozzle has replaceable internal components, the method of access and spare parts should be clear from the time of purchase. Cleaning with the wrong tool or material can damage the outlet geometry or seals.

21–12. Mechanical coordination, lighting and control

The nozzle should remain fixed in the set position. The base, connection and support must be compatible with the flow forces, the weight of the assembly and its possible movement.

In the placement, the space for adjusting the angle and removing the product for service should be provided. A nozzle that is not accessible after stone and floor construction will be difficult to maintain.

Lighting should also be coordinated with the shape of the water. In choosing the light around the nozzle, the diameter of the central opening, the position of the water outlet and the radiation path are important. The lamp or frame must not obstruct air intake or adjustment access.

For moving nozzles, full range of motion, cable and hose routing, and stop mode are checked. For the cut-off nozzle, the water condition at the time of shutdown and the behavior of the network must be known.

An independent steering wheel in software alone does not create hydraulic independence. In the joint circuit, the change in the status of one group may affect the pressure of other groups.

21–13. Nozzle selection based on project location

It is better not to compare the options with a single height or photo. The following three examples show the decision-making method.

Urban square with long distance view: readability of volume, stability of effect and splash control are important. Specific jets or bulk effects can be checked; The final choice depends on the wind, the dimensions of the pond and the required energy.

Forecourt of a commercial center: the quality of near vision, the sound of water, the path of people and the muted appearance are important. The subtle effect will be suitable when the flow, water and maintenance conditions can be provided.

Plaza with direct people contact with water: nozzle assembly, floor plate, pressure and work pattern should be designed and evaluated for this application. Use of a decorative nozzle simply because it is flush mounted does not qualify it for public contact.

In all three situations, the purchase cost must be weighed against the pump, control, treatment, access, and maintenance requirements.

Figure note from the source manuscript

Figure 3–21: Three frames of different project positions, with a brief explanation of the purpose of nozzle selection. Suggested subtitle: "The appropriate choice is obtained from the relationship between the water effect and the location and the way of using the space." Hypothetical images should be identified as "conceptual design".

21–14. Sample test and performance acceptance

For sensitive projects, sample testing should be done before finalizing the bulk purchase. The test conditions should be close to the design conditions and the actual flow rate and pressure should be recorded.

The proposed test includes the following items:

• The shape of the water at the required heights;

• flow rate and pressure at a specific reference point;

• flow continuity and deviation from the set direction;

• Effect of water level change;

• Landing and splash area;

• quality of light and sound of water;

• Disconnection or movement response;

• Ability to open and service.

In the group test, the pressure of one nozzle near the pump is not enough to confirm all the nozzles. Distant nozzles and critical paths should also be checked.

Tolerance of height, uniformity and direction should be determined in the project documents. The term "optimal performance" without benchmarks reduces the possibility of clear delivery.

Figure note from the source manuscript

Figure 4-21: Archival photo of actual nozzle test with height scale, pressure sampling location and flow rate recording. Suggested caption: "Nozzle testing should relate visual effect to measured hydraulic conditions." Values ​​should only be entered from the actual test report.

21–15. Maintenance, troubleshooting and identification of nozzles

A change in effect does not always mean a nozzle failure. Troubleshooting should also cover network and installation conditions.

This table is a guide to start the investigation and does not determine the exact cause of the failure.

For each group of nozzles, a certificate containing the product code, number, installation position, reference level, design flow and pressure, angle, control group and maintenance method should be prepared. The numbering map must be coordinated with the control panel and program.

The final selection is complete when the desired effect, hydraulic requirement, installation conditions and maintenance method are all determined. In Chapter 22, fountain pumps and their selection principles are reviewed; Includes performance curve reading, efficiency, submerged and dry pump, remote control and pump selection for different display modes.