what size pipe to use in farm irrigation

Information technology is strongly recommended before y'all brand the decision to purchase any pipe and riser system yous place your private requirements. This will help guide your decision in relation to the type of equipment you lot purchase.

Installation of this blazon of equipment is a pregnant business conclusion and growers are encouraged to practise a fiscal assessment that appropriately considers the investment. This should consider:

• greenbacks flow impacts
• capital expenditure versus functioning and maintenance
• payback period
• taxation implications
• benefits (productivity and labour) of the investment.

It is important you seriously consider the alternatives such every bit earthen channels.

Given the appropriate soil conditions, design, construction, operation and maintenance, channel systems tin can be toll effective and efficient. Talk to an irrigation surveyor and designer to ensure a piping and riser system is right for your particular situation.

Once you are certain a pipe and riser organisation is what you want or demand, consider the following.

Period rate (or belch)

What flow rate practise you want or demand? Generally the response is in the range of 1220ML per day. The answer to this helps to make up one's mind the bore of pipe required and the likely pump specifications.

Yous should seek advice from an irrigation surveyor and designer to ensure the menstruation rate meets the requirements of the farm'south physical characteristics and/or the ingather being grown.

It is important the flow rate matches the crop's requirement, that is, information technology fairly fills the root zone. Too pocket-sized a flow rate may mean h2o ponds besides long pushing past the root zone and contributing to deep drainage. Too big a flow rate may result in water not infiltrating deep enough to satisfy the crop beingness grown resulting in lost product.

You should practise a Whole Farm Plan (WFP) (or alter their existing one) to reflect the pipe and riser organization design. This will ensure the system is compatible with the proposed layout as detailed on the WFP and considers hereafter expansion.

Length, shape or layout of the pipeline

The answer to this volition assist determine the diameter of piping required and the likely pump specifications. In addition you might desire to install a system on part of the farm and expand the system later. This needs to be considered now. If expansion is not considered initially and you want to do information technology after the system will be besides small and require significant modification, or even a complete new system.

Information technology is not common for systems to be a simple straight length of piping, they often take pipe teeing off and may be looped to satisfy the concrete layout of the holding. This will influence the pipage size and pump specifications and highlights the importance of proper design and consideration of all options during the design stage.

How many trophy to gargle at the one time

Suppliers suggest ideally one bay at a fourth dimension should be irrigated to ensure a toll effective organisation that meets the requirements of the crop being grown.

The more bays you want to irrigate at in one case the greater the demand on the system and then the pipe and pump specifications will need to be altered. It will touch on the flow rate and the ability of the system to deliver the correct application rate to satisfy the ingather being grown without losing h2o from the production organization, (deep drainage beneath the active root zone). It is too difficult to deliver the same flow rate out of two risers at the same time which could pb to inefficient irrigation on one or both bays.

If automation is something you are considering, remember it is easier to automate irrigation if one bay is irrigated at a time.

Once these  considerations are known, the supplier or designer is able to decide the pipe size required to deliver the required period rate.

Ongoing operation cost per ML

This is i of the most of import considerations you will demand to make. A relationship exists between piping size, pump efficiency, head loss  and energy costs that will touch on the cost to pump a ML of water for the life of the system. If you get this incorrect, the overall cost (capital expenditure plus functioning and maintenance) will be significantly college than it needs to be.

You should always aim to design a arrangement that delivers the required menses whilst minimising free energy requirements. This ensures the system remains as economically efficient as possible for the life of the equipment.

Using a gravity system

Gravity systems tin can be installed (a organization that does not crave a pump) but pregnant head is required that is rarely obtainable in northern Victoria. The caput required would need to be greater than approximately 1 metre for these systems to fairly meet irrigation requirements.

If you have suitable caput then this pick should be discussed with your irrigation surveyor and designer or pipage supplier.

Determining pump efficiency

Pump efficiency is a complex relationship that volition vary due to a range of factors including:

• impeller/pump design and type
• impeller diameter
• full head
• speed and flow rate.

All reputable suppliers will have curves that demonstrate their pump efficiencies. Information technology is important y'all ask to see these and understand them and then you tin decide which pump provides the flow rate you require at the highest possible efficiency.

The higher the efficiency the more than h2o information technology will move per watt of energy.

Also consider the efficiency of the pump beyond the full range of the system —  that is, how information technology performs at the closest, furthest and all risers in betwixt.

Head loss

Caput loss is the total hydraulic resistance against which the pump must operate (friction). It means the effort required to push water through the pipe and deliver the required menses rate at the furthest outlet/riser. It is described equally metres of head at the pump. The simplest style to reduce the head loss is to increase the pipe size.

The aim is to design a system that results in a head loss of between five and 10 metres.

Oftentimes smaller pipes are installed to reduce the capital cost. This determination creates a higher head which is overcome by upgrading the pump/motor set. Notwithstanding, the higher the head the higher the pressure required to deliver the flow rate. This may issue in issues with leaks, particularly around closed risers, and volition upshot in college pumping/energy costs.

Level of flexibility required to be congenital into the arrangement

Flexibility should e'er be a consideration in the design phase —  such equally:

• variable speed drives
• expansion at a later engagement
• increased period rate
• automation.

This is best done as a component of a WFP. A number of designs should exist washed to show the total range of flow rates for various options. If the limits are pushed there is very limited flexibility one time the organisation has been installed.

It is disquisitional at the first of the process irrigators seriously consider what they want to take in the long run. It is costly to make changes once the system is in the basis. This includes elementary things similar retro-fitting automation. In many instances this cannot be done without major modifications if the system has been installed without prior planning.

Piping and riser systems provide irrigators with greater flexibility in which bays get irrigated. A single bay can be irrigated one day and another on the opposite side of the system or farm tin can be irrigated straight afterwards. Traditional channel systems are less flexible as groups of bays often need to exist irrigated i after the other to take advantage of the channel being filled.

Looped system

Ordinarily a single pipe leaves the pump and moves through the property to evangelize water out of the risers to the irrigation bays. A looped system has ii pipes that are joined somewhere on the property to grade a "loop".

Looped systems are used to reduce the size of pipe required to deliver the necessary catamenia rate. It is important trophy can exist irrigated on all lengths of the system to avoid expressionless lengths of pipe. These systems are able to evangelize the required menstruum charge per unit at all spots along the pipeline.

It is not possible to install looped systems in stages, they need to exist fully installed. Go along this in mind if you are considering staging installation over fourth dimension.

Capital expenditure versus performance and maintenance

It is possible to reduce capital expenditure by using a smaller pipe and increasing the size of the pump/motor prepare required to deliver the desired flow rate. For case, to increase the pump/motor size on a pump may cost $yard (subject to ability requirements and pump specifications) while , to increase the pipe size from 355mm to 400mm may cost $ten,000 for approximately 1km of pipe. This needs to be given careful consideration considering operation and maintenance costs will be greater. Also future expansion and organisation flexibility volition exist limited if the pipe is as well small.

If the volume of water being pumped through the system each year is relatively pocket-sized, additional consideration may be warranted. Some people will argue you tin compromise on some of the other factors such as the pump/motor gear up if this is considered against the capital letter toll over the life of the projection. The reduction in uppercase cost may mean additional pumping toll per ML results in a net benefit across the life of the system.

Velocity

Enquire what velocity the system is designed to operate at. If it is greater than 2 metres per second (2m/s) y'all need to empathize why, as it may exist uneconomic long term due to college operating and maintenance costs.

Diesel or electric motor

Ofttimes there is no choice considering it is too plush to connect power but if you have an choice, there are some subjective and economical considerations. To help make this decision ask your designer to provide an estimate of the pumping costs for both options and what the capital letter costs would be. Depending on the volume of h2o you plan to pump each twelvemonth information technology may be attractive to install a diesel fuel motor. Too consider such things as:

• refuelling diesels
• bunding effectually fuel tanks
• automation
• safe
• greenhouse impacts
• operating life and general maintenance requirements.

Riser size

Consideration should be given to the size of risers you would similar to install. For instance a 450mm piping should have a 400mm riser.

Installing smaller risers volition result in increased operation and maintenance costs considering of caput loss and problems associated with launder when water is delivered onto the bay.

Install as big a riser as possible to assist alleviate these problems but remember ease of structure will affect cost.

It is harder to install a riser the same size as the pipage than one that is a size smaller than the pipe.

Variable speed drives (VSDs)

VSDs provide growers with flexibility and reduced energy consumption. They are an electronic device that allows the speed of the motor to be accurately controlled pregnant growers tin speed up or boring downwards the application of water from the pump/motor set. They allow the grower to control the period rate at any point in the system.

Shrouds

Are often used on risers to ensure they can be opened and closed without the operator getting wet. This can increment wash as the h2o is directed to a smaller expanse (more energy on a smaller footprint).

Suction pipe

Suction side of the pump needs to be considered especially if there is some distance betwixt the pump and the supply point. It is possible that on outset up the piping may collapse. This weakens the wall and tin only be fixed past removing the damaged section of pipage. To prevent this, heavy walled pipage should be installed and/or a pump pit or a machinery to let the pump to be started at lower speeds.

Flooded supplies

Conversely flooded supplies (where the h2o level on the supply side of the pump is higher than the pump) may need additional technology solutions to protect the equipment. For instance, a surge tank may exist required when shutting down the organization to deal with the energy of the water in the suction pipe.

Pipe joins and welds

Some companies place each weld with a postage stamp ensuring welds are completed by certified technicians to Australian Standards.

Ensure your supplier meets this standard and ask to run into their technician's qualifications. Adhering to correct procedures that are to the Australian Standard volition ensure welds are equally strong every bit possible prolonging the life of the organization.

Other sources of h2o

Dairy effluent tin be pumped through these systems and this volition be of benefit to some irrigators. Similarly other supplies such every bit groundwater may be pumped through the organization. These culling sources of water may be harsher on the system and appropriate shandying and engineering solutions should be employed to minimise whatsoever impacts.

Reuse and channel connections

Reuse and channel connections may require a ane way valve to prevent the channel being emptied to the reuse and vice versa. This might exist particularly important if you lot are using effluent through the system.

Trenching and backfilling

You should consider trenching and backfilling during the installation of the system. It is best if this is done to a specified standard which is agreed upward front, so bug associated with poor backfill material is eliminated.

Some pipe supply companies prefer pump and digging work is considered and contracted separately to the pipeline. This ensures growers have a human relationship with the pump supplier and excavation visitor so they get proficient advice and accept someone to get to if they have problems relating to these specific aspects.

Opening and shutting risers

In that location are two means a riser can be open up and close — transmission or automatic. A range of options be within these categories and these include:

• Transmission — the irrigator approaches the riser and manually opens or shuts the riser using a handle attached to a spiral.
• 12 volt — a motor is attached (permanent) to the screw machinery. The irrigator carries a battery and attaches leads to the motor. This is used to open up and close the riser.
• Timers — can exist fastened to the 12 volt openers to shut and open risers at a predetermined set time.
• Permanent batteries and solar panel — tin exist attached to each riser, a button is pushed to open and close the riser.
• Full automation — risers can be fully automated to open and shut.

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Source: https://agriculture.vic.gov.au/farm-management/water/irrigation/pipe-and-riser-irrigation-systems

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