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Pump Stations...Streamlining Design

ELIZABETH LEXAU | Miscellaneous

With water an increasingly scarce and valuable resource, it’s more important than ever for landscape irrigation designs to include efficiencies in every component of the system—including the pumping equipment.

Today, manufacturers are making it possible to incorporate finely-tuned, conservation-oriented pumping systems into a wider array of applications.

In recent years, pre-manufactured pump stations have become welcome additions to the irrigation scene. These all-in-one units give customers a complete package, tailored to the unique needs of each project. They contain the pump, motor, electronics and all other components, which are tested to function seamlessly together. The packages are assembled to exact specifications at the factory and delivered to the site ready to connect and go.

More manufacturers are including energy-saving Variable Frequency Drives (VFDs) in their pump stations as well. Instead of running at a constant speed, these drives conserve energy by automatically adjusting when system demands vary. They also save wear and tear on the entire irrigation system by eliminating rough starts and stops.

Computerized communication and pump monitoring systems can further improve efficiency—especially in larger applications. These reduce the risk of damage from breaks and help managers watch the performance of the pump in tandem with the rest of the irrigation system.

“It’s important for irrigation professionals to know more about pumps and pump stations, because there are so many options and applications out there,” says Allen Munro, Munro Systems, Grand Junction, Colorado. “These professionals need to have a good understanding of what their needs are and what the best pumps and materials are to meet those needs.”

This doesn’t mean they have to be experts. In fact, there are so many variables involved in choosing pumps and other components that tapping into someone elses expertise in this area is often more valuable than trying to develop your own. Finding a reputable manufacturer who understands your needs, who can provide you with an economical solution, and then back it up with service and support is often the most critical step.

One stop shopping

Joe Varonin, landscape architect with TCLA, Inc., Valencia, California, has noticed big changes in the demand for pumps in recent years. “I’ve used more pumps in the last five years than I did in the previous twenty,” he says. “Flatlands are already built out and more communities are going into the foothills.

Water is becoming scarce and pressures are low.”

Watering restrictions are adding to the need. Adequate pressure is needed to irrigate in the shorter timeframes mandated by regulations in many communities.

“Water windows are one of the most important parts of design today,” says Varonin. “If you have a large project and you’re limited to watering from 6:00 am to 10:00 am, how are you going to do that without enough pressure?” Even if pressure is adequate now, pumps are sometimes needed to buffer a system against future pressure loss. “A good irrigation designer will design for 75% of available pressure,” says Varonin. “In a new community, the pressure might be adequate but three years down the road, as the community’s built up, the pressure drops.”

In years past, Varonin designed a pumping system for each application from scratch. The availability of prepackaged pump stations for his projects has made the job much easier.

“In the last five years, pump stations have really caught on fire,” says Varonin. “Prior to that, I was still spec’ing out pumps without VFDs. But manufacturers started to offer pump stations and the demand has been there. They arrive in one piece—as a package deal—and I prefer that. They have expertise behind them.”

That expertise is what makes these systems so attractive. Pumps and their related components are complicated systems, with numerous variables that impact performance. Pump stations put the responsibility for this complicated design into the hands of one manufacturer.

“The industry was looking for a solution provider,” says Hans Stewart, marketing director, ITT Flowtronex, Dallas, Texas. “What we do is take the pump, controls, all the valves, the filtration, and the precision measurements and bundle it into one prepackaged and pre-tested system. This offers single-source responsibility.”

Irrigation consultant Mitchell Langley, MDL Consulting in Searcy, Arkansas, has designed plenty of pumping systems on his own but defaults to pre-packaged pump stations whenever possible.

“There are costs associated with being able to pull it off a truck and plug it in versus a contractor building it,” he says. “But if the money’s there, I prefer to go with a pre-fab product.”

This approach reduces the potential for error and miscommunication between the irrigation designer and installation contractor when trying to design it piece-by-piece. “There’s so much detail and so many components that go into putting it all together,” says Langley.

“If I detail it out expecting a contractor to give me the exact products I ask for, more can go wrong.”

Detailed design

Tony Adamson, pump and sales marketing manager for Rain Bird Corporation, Tucson, Arizona, talks about the numerous factors that go into pump station design.

“We work with customers to design the system and provide a cost estimate depending on their needs. Every site is unique. There’s a unique water source, unique flow requirements depending on the irrigation system, and unique pressure. Customers may have items they specifically want for their system. Some want a flow meter. Some want the pipe to go down through the concrete versus through the side.”

Other variables include the required water window, available power service, proposed placement of the pump station, the elevation and the piping size. Depending on the application, there may be filtration needs as well.

The first consideration is the water source. “Is it a public water source?” asks Adamson. “In that case, you’ll be using a booster station where you’re taking the inlet pressure and boosting it to a higher pressure to irrigate with. Or do you need to draw the water from a pond or well? In that case, it will be a suction lift application.”

Flow and pressure requirements are next, says Adamson. “What’s the pressure and flow needed at the discharge of the pump? That’s the information we need to select the size of the pump.”

Confirming the water source and inlet pressure before finalizing the design is a critical step. “You don’t want to undersize or oversize a pump,” says Adamson.

Available power is always a top concern. “Some pumps are required to operate on three-phase service, so if the application has single-phase service, that might limit options,” explains Adamson. “Verifying it up front is critical. If we designed it around three-phase and get out there to find it’s single-phase, it can’t be connected.”

Fortunately, an extensive series of checks keeps this from happening. “We have a team that works with our customers to provide us with these answers,” continues Adamson. “They talk about what the application is like and how they’re going to set it up. They ask a lot of questions as we go through the design process.”

Using this detailed information about the site, manufacturers produce a pump station uniquely designed for that project.

The contractor provides a concrete pad and the pump station arrives by truck with service technicians ready to hook it up.

Streamlining energy use

Variable frequency drives are becoming a new standard in many pump stations.

“Variable frequency drives have made a huge impact on the way pump stations are built and used,” says Munro. “With VFDs, we’re able to vary the amount of energy that is used, based on the current need. We’re now using the correct amount of energy for an application, as opposed to creating a consistent stream of energy and wasting that energy at times when we don’t need it. It’s more efficient and helps extend the lives of everything from pumps to valves to pipe.”

Adamson compares VFDs to the gradual acceleration of a car. “We call it soft starting. I can start slowly and manage speed based on flow demand. Demand may depend on how the system is set up. One area may need 300 gpm. Another area may only require 200 gpm. VFD will change the speed to fit that need.” Without VFD, the system would run at the constantly higher speed even when demand isn’t there.

“It’s like revving up a car while you have your foot on the break,” says Adamson.

Who’s minding the pump

Pump monitoring software coupled with central controls offers another way to improve pump efficiency. This is especially important in large applications, where the risk of breaks can lead to disastrous water loss and property damage. Software can be programmed to alert managers when there’s an irregular flow in the system or to shut off entirely in the event of a break.

“What SmartPump does in conjunction with central control is take current information from the pumping system and look at what’s happening in the irrigation system,” says Adamson. “If a pipe breaks, the pump wants to run because there’s a drop in pressure. But the central control system will notice that you don’t have a sprinkler on, so it will tell the pump to shut off.”

The software can also determine whether the system is using the pump to its full capacity. Using it at full capacity means it won’t need to run longer than necessary to complete irrigation. This saves energy, saves wear and tear on the pump and helps ensure that irrigation will be completed in the shortest time possible to avoid exceeding water windows.

Choosing a pump station

There are many factors to consider when choosing a pump station. With a complex product like this, making sure you have expert support is imperative.

“Price and availability of local service are both at the top of my list,” says Langley. “Especially technical support. There are times I’ve used a pump station and I was pleased with the product, but when you lose service, where do you go from there? Service trumps.”

Going with a national brand that can provide service globally is one way to guarantee that support.

However, Langley says not to discount smaller manufacturers. He uses products from both.

“There are smaller regional pump station manufacturers that offer high quality, too. They may be able to sharpen their pencils a bit more and may also have a reputable product. Look for references, the number of jobs they’ve done and product reports. Dig into information on the web. Ask yourself if they’re going to be around when you need them.”

Munro advises not getting caught up in an overly elaborate system just because the technology’s available.

“With the advancements in the electronics industry, it’s tempting to add complexity to the electronics of a pump station,” he says. “I recommend that people keep things as simple as possible. When you add complexity, it doesn’t always make the application better suited to the job. With more complex electronics, the maintenance and repairs can become more complex and difficult, and often there is not much value added. It’s important that irrigation professionals understand what the electronics do and what they’re for. No one wants to get dazzled by bright lights, only to find that their product is not easy to maintain.”

 
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11.18.2012 at 10:45 Reply

This article covers all the concept of irrigation pump station and gives us all kind of predesign guidlines.

 

 
 
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