As technology continues to progress, the irrigation industry never ceases to create new, powerful ways to manage and monitor water flow. Join Rob Aldinger of Precision Pumping Systems for an overview of how modern technology is helping make pumping systems more efficient than ever. Rob will discuss how devices such as variable frequency drives (VFDs) work with pumping equipment in creating systems that are safe, simple to operate, and easy to troubleshoot. He’ll also discuss how the use of programmable controllers and cloud-based remote control can optimize these systems’ efficiency and ease of operation.
Note: The following catalog of content covered in this webinar is time stamped to allow you to follow along or skip to sections of the video that are relevant to your questions. You can also search for content on this page using the FIND command in your browser (CTRL + F in Windows, Command + F in Mac OS.)
- Centrifugal Pumps
- Pumping in Series
- Pumping in Parallel
- Turning Things On and Off
- Pump Systems Must be Designed to Supply Maximum Possible Demand
- Variable Frequency Drives (VFDs)
- Why Older Technology Is Not Up to the Task
- Modern Control Panels
- Remote Control & Monitoring
- Total Automation Integration: Packaged Systems
0:00 – 3:03: Intro/TOC
3:04 – 9:27: Centrifugal Pumps
The centrifugal pump is the most common method for pumping water.
A centrifugal pump uses an impeller to move the water.
Through centrifugal force, the pump converts energy to a variable combination of pressure and flow.
Since the combination of pressure and flow are variable, when flow increases, pressure must decrease and vice versa.
The pump curve (3:30)
Centrifugal pump impeller (3:57)
How an impeller works (4:55)
Impeller parts (5:43)
Note: The pump and the motor are two separate things and are generally made by different manufacturers.
Typical end suction centrifugal pump stations (6:45)
Pump RPM (7:23)
How impeller diameter affects pump output (8:17)
9:28 – 11:59: Pumping in Series
Pumping in series means an impeller pumps into another impeller and possibly into an another and another. Every time that that happens, it's moving exactly the same amount of water but it's increasing the pressure.
Vertical Turbine Pumps (10:10)
A vertical turbine pump is designed to pump in series, so it's one pump with multiple impellers.
Submersible Turbine Pumps (11:06)
Submersible turbine pumps are essentially the same device as an as a vertical turbine pump, except the motor itself is actually submerged underwater rather being above the pump. The motor is under the pump.
12:00 – 20:43: Pumping in Parallel
When individual pumps pump into a common pipe, the result is the opposite of when they pump in series: Each pump adds capacity but the pressure remains constant.
Three vertical turbine pumps pumping in parallel (12:49)
How rotational speed affects pump output (13:27)
Question: How do you determine the minimum depth that the top impeller should be below water level to prevent cavitation? (16:51)
Answer: Every pump should have an associated minimum submergence, and every pump is different. You'll really want to avoid having the velocity or having the water too close to the suction of the pump so it creates a vortex that draws water into the system.
Question: Is one of the two – vertical or submersible – more efficient in gallons pump per amp drawn? (18:16)
Answer: Vertical turbine hollow shaft motors tend to be slightly more efficient than submersible motors. Submersible motors were designed to go down inside of well casing, so they'll likely lose a small amount of efficiency that will likely be insignificant.
Question: When would you not want to use a variable frequency drive (VFD)? (19:17)
Answer: VFDs are useful in most applications – even the simplest. About the only application where a VFD is not recommended is in applications where the pump is filling a vessel such as a tank or reservoir, where, when the level drops, the pump turns on and the vessel takes a considerable amount of time to fill, when the pump then turns off. In this type of application, a VFD won't provide much of a benefit aside from the soft starting of the pump.
20:44 – 26:59: Turning Things On and Off
The manual closing of a full-voltage circuit (21:10)
Magnetic contactor (21:30)
Hand-off-auto (HOA) switches (22:10)
Unless you're a pump technician who's knows exactly what you're doing, it's not recommended to turn an HOA switch to "hand."
Pump automation (23:34)
On/off timer (23:44)
Remote start (23:50)
Pressure switch (24:12)
Soft starter (26:07)
27:00 – 37:19: Pump Systems Must be Designed to Supply Maximum Possible Demand
Variable speed control (29:08)
Question: What is a pressure set point, inlet pressure, and discharge pressure, and how are they related? (31:25)
Answer: A pressure set point is where we have programmed the pump station to operate. So in our in our previous examples, we wanted that pump station to always maintain 50 psi. Now, it could be anything, whatever it is for any particular application. So that's our pressure set point. So the output of the pump is designed to only provide 50 psi, no matter what happens into the system. OK, now you're talking about the inlet pressure set point, that's typically going to be a booster system where we have some kind of pressurized water entering the pump, the pump is actually adding pressure to it before it sends it out into the system, in order to have enough pressure for whatever devices are being operated out there. Not very often do we see a set point there, we're going to be receiving whatever is providing the other pressure pumps or something else at another location are going to whatever pressure they're providing to that pump, is how is our pump's going to take that and then increase it accordingly.
Question: So the variable pump speed will only increase as demand is needed, not at a certain time or a scheduled time? (33:00)
Answer: You can do a lot of things with variable frequency drives and monitor technology. I can't think of an application where there would be a set time where pressure would increase. So in the simplest of applications, you're going to see what we just saw, which is we've set that pressure to be maintained 50 psi, no matter what happens in the field, it's sensing pressure that's in the mainline. And whenever that changes, it reacts accordingly, it turns the pump on, ramps it up, ramps it down, turns it off, whatever is necessary, I can't think right now have an application where you would do that on some sort of a timed interval or, or anything else, but not say that it can't be done. But I'm not sure what type of application that we use for one of the things that you can do with VFDs is you can have multiple pressure set points. So if for example, you have some zones, and whatever your project is, that are at maybe various altitudes, or possibly, you know, much farther away from one than the other, where you might need an increase in pressure for the one that's farthest away or the one at the highest altitude. If you can feed some information back to the pump station control system that lets it know which zone is operating, you can actually set most multiple pressure books set points so that we know that that high zone over there needs another 10 psi so when it's operating it will operate at a higher pressure.
Question: If there's a leak in the mainline, will the pump be cycling on and off? (34:39)
Answer: Yes, this is a possibility.
In this case, you might want to consider using the pump start relay to put the pump to sleep until irrigation takes place that can eliminate a lot of the leakage. In some cases in extremely old, large piping networks, you won't be able to do anything about the leakage. In those cases, you could add a pressure maintenance pump, or what's known as a jockey pump, which can handle any low flow applications while also maintaining pressure in the system to overcome the leakage. If you're using a VFD, the pump will ramp up and down slowly anyway, and you can also program in timing or even add a user-selectable function that puts the system to sleep on based on the flow rate.
37:20 – 41:29: Variable Frequency Drives (VFDs)
A VFD is just a device a computer really, that automatically starts, stops, and varies the speed of a pump motor to regulate output.
Pressure transducer (37:53)
Magnetic flow meter (38:35)
Level transducer (40:00)
41:30 – 43:58 Why Older Technology Is Not Up to the Task
Question: Is it common to use pressure tanks in combination with a VFD to minimize cycling? (43:08)
Answer: it's application dependent. If there's just no good solution to overcoming leakages or low flow situations, and you just want to buy some time between the time that the pump comes on and goes off, pressure tanks are definitely used in those applications.
43:59 – 54:41: Modern Control Panels
HMI touch screen (44:47)
Programmable logic controller (45:00)
PLC /HMI control platform to monitor pressure and flow (45:05)
Fault logs (47:30)
Trend logs (48:09)
Default button to return to the factory settings (48:54)
Question: Can you adjust these settings remotely utilizing the celcom? (49:18)
Answer: Yes. Anything you can do locally can be done remotely.
Question: Is there password protection? (49:58)
Question: Do most VFD controls allow for a ramp-up period that is adjustable to keep a pump from reaching full RPM for a certain time period? Slow fill of the lines? (50:20)
Answer: Yes, the ramp speed is fully adjustable both up and down. As far as filling in the lines, most systems have a line fill routine programmed into it. So when you start the system up originally, or if there's an event such as a power failure, and all the pumps turn off and the system and pressure drains down in the mainline significantly, when the system comes back on again, without that routine and those settings, if the pressure in that system had dropped to zero, every pump in the system will ramp up quickly and force water into the system extremely quickly. So we have a ramp up routine that will monitor pressure and very slowly increase the pressure in that line so you can slowly move the air out of the system.
Question: Does each pump motor have a separate VFD when you have multiple pumps on the system, or does a single VFD control all motors? (51:36)
Answer: It can be done either way.
Instructions for Using VFD for All Control Instead of a PLC (54:42)
Instructions for the Same Adjustment Using a PLC (55:07)
55:28 – 57:40: Remote Control & Monitoring
57:41 – end: Total Automation Integration: Packaged Systems
- Vertical turbine pumps
- Submersible turbine pumps
- Sand media filters
- Suction scanner filters
- Air-conditioned control panel for the entire system
Managing water usage (59:50)
Automatic suction scanner filtration (1:00:59)
Water re-capture systems (1:01:42)
Integrated buildings & enclosures (1:01:50)
Question: With permission settings available for the controller, can you get notified when changes are made? And of who made them? (1:02:55)
Answer: Yes you can.
Question: Why do most manufacturers not use cascading? VFD? (1:03:32)
Answer: Unfortunately, that's a question for the engineers and technicians.
Rob Aldinger's contact info:
- Email: Rob@gopps.us
- Phone: +1 208-631-8082
Question: Can different manufactured pump stations be linked to lake-fill pumps? (1:05:37)
Answer: Linking to any peripheral devices typically has more to do with just the communication between the two devices and what types of devices are being used. So I guess the short answer to that is yes.