Messages

1471

Pumps, Wells, Tanks, Controls / VFD's are Costing Too Much!

« on: October 10, 2008, 01:01:42 PM »

Cary,
See attached picture of cycle stop installation. Valve worked like a charm, no worries, no problems all season; irrigation water ends on 1 Oct.

Kirk

1472

Pumps, Wells, Tanks, Controls / Grundfos SQE

« on: September 23, 2008, 11:39:42 AM »

There is no reason why the one well pump cannot do all the jobs required. That is kind of the point of "constant pressure". "Constant pressure" really means "variable flow". In order to maintain "constant pressure" the pump system must be able to "vary the flow" to match the amount of water being used. That means the pump should be able to vary the flow to match a single 2.5 GPM shower in the house, as well as a 6 GPM sprinkler in the yard, or both at the same time.

There are new style VFD's available but, VFD's are not new. Pump and VFD companies keep coming out with new models of VFD's, that are supposed to solve all the problems of the last VFD. They will have a few "upgrades" for the new VFD to work out more bugs, before they come out with the "newest" VFD that for sure this time will solve all the problems. The customer keeps being told "we have the problem fixed for sure now, just purchase the new version". A VFD is made with the same microprocessors that are used in lap top computers. Therefore you will have the same reliability and length of service from your water system, that you have with your lap top computer. What is the oldest computer you have that still works? And if you had problems with a computer over 3 years old, could you get parts for it? NO, of course not. They no longer make the Pentium 2 chip, now they are making the Pentium 4 or Centurion chip. So no parts are ever available to repair a VFD. Any problem, and you must purchase a new unit. Does this sound like a predictable, familiar, and money making proposition for the manufacturer? Of course it does. Making money for the manufacturer at the expense of the end user, is what VFD's are all about.

Cycle Stop Valves were invented to replace Variable Frequency Drives. We have been successfully replacing VFD's with CSV's for more than 15 years. When you replace a VFD with a CSV, you get the same or even better "enjoyable constant pressure". However, the CSV is a permanent fix for the VFD. No more "patches" or "upgrades". No more having to go to the well house and unplug and restart the computer regularly. No more lights with dimer switches flickering. No more interference with radios, TV's, telephones, etc., etc..

The Grundfos SQE is converted to an SQ, when the CU301 controller is removed. The SQ controlled by a CSV and regular pressure switch is much more dependable than when used with the computerized CU301 controller. Then when the little 10,600 RPM SQ pumps fails, you already have the CSV controls needed to replace the pump with any standard 3450 RPM pump, which is also much more dependable and long lasting.

Attached is a drawing of how to change out the CU301 controller and install a CSV. Also there is a before and after picture of a recent SQE to CSV conversion. Let me know if you have further questions.

1473

Pumps, Wells, Tanks, Controls / Grundfos SQE

« on: September 23, 2008, 11:37:42 AM »

From a Concerned Home Owner
4 years ago, we opted to 'upgrade' to the constant pressure system. I've just spent some time here reading about them, and am now underwhelmed. Thus far, we've had to replace the pump at 2 years and the controller box at 3 years.

The pressure is awesome, but it never did set well with me that there's no pressure tank and every open of the tap caused the pump to run.

We have been talking with several irrigation system people and our neighbor and friend, the well driller. (not the same one who did our system) Both parties say this system is more than ample to run our irrigation set up, which encompasses about 1/2 acre which will be primarily Rainbirds. There will be several lines of bubblers as well.

We're toying with the idea of dropping a shallow irrigation well with a Flotec sprinkler pump, but if the current house well wouldn't be taxed significantly and supply ample water, we'd simply use the house well. We have about 10 gpm flow off the current setting at 70 psi.

My first dillema was irrigation well vs. house well thinking the Grundfos should do it. Now, I'm realizing that the Grundfos will probably go out in the next few years with or without the watering system. We'll then be out the cost of replacing it, as well as having spent probably $1200 or so to drop an irrigation well.

In my position, what would you suggest? Irrigation well now, and replace the Grundfos with a standard pressure tank and CSV set up when it goes? Would you simply install the irrigation system on the current house well and then replace the Grundfos when it dies, which would probably be sooner as a result of the additional demand?

1474

Pumps, Wells, Tanks, Controls / Multiple Check Valves

« on: September 23, 2008, 11:35:08 AM »

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I think it is just one of those things that works on paper, and not so good in reality. You don't want water to go backwards when the pump shuts off, so if one check valve is a good thing, then a hundred check valves would be better.

However, the more check valves you have the more friction loss you have. A bigger pump is needed if you have much friction loss. Other than that, you would still think an extra check valve or two would still be a good idea for backup.

Many times, multiple check valves do work OK when everything is new and working perfectly. The problem comes when any check valve leaks a little bit, or doesn't close quite as fast as the check valve above it. Then a negative pressure is created below the top check valve.

If the top check valve is above ground, the vacuum can draw contaminates into the line. No matter if the top check valve is above ground or in the drop pipe, the negative pressure will allow the pump to start to the right of it's curve. (In other words "wide open") The pressure above the pump will change from negative pressure to positive pressure in a fraction of a second. The effect is, the column of water below the top check will "punch" the top check. This is much like a Boxer "punching" you in the face. It creates a shock wave that travels throughout the water lines. At every outlet valve, elbow, tee, and dead end in the pipe, the shock wave turns into water hammer. Water hammer causes everything in the pipe system to experience pressure 10 times what you see on the gauge. On larger pumps it usually causes the pressure switch to bounce on and off like a telegraph.

You can remove the upper check valve when they start causing problems, or you can install only one check valve at the pump and not have the problems.

I have installed systems as deep as 2200' with only one check valve. You just need a good check valve, and to start and stop the pump at almost deadhead pressure conditions.

1475

Pumps, Wells, Tanks, Controls / 80 Gallon Tank replaces 12,000 Gallon Tank

« on: September 04, 2008, 10:47:19 AM »

Marion County, Florida is using a 4" Cycle Stop Valve and an 80 gallon bladder tank to replace a 12,000 gallon hydro pneumatic tank.  Several community water systems in Marion County are using Cycle Stop Valves and small bladder tanks to supply "constant pressure" to their customers.  These systems are set up to be temporary, while the huge pressure tanks are off line for service and cleaning.  However, it should be noticed that the system pressure is much better controlled, and the pump cycling and water hammer events have disappeared after installing the CSV's.

The first picture shows the submersible well pump being controlled by a Cycle Stop Valve and an 80 gallon pressure tank.  The 12,000 gallon tank that is out of service is pictured in the background.

The second picture is of the pressure recording chart for a week of service.  The first 5 days of this chart was with the 12,000 gallon tank, the last two days shows the recorded pressure for the CSV controlled system.  In the first 5 days with the big pressure tank, there was 291 cycles.  That is 2.38 cycles per hour, 57 cycles per day, or about 21,000 cycles per year.  Notice the regular "heartbeat" on the graph as the pump cycles on the big pressure tank.  Each "heartbeat" represents a water hammer event that happens throughout the entire system.  It also represents considerable abuse on the pump, motor, controls, check valve, and piping system.  The system is continually cycling between 53 and 72 PSI.  This is also the variation in pressure that all the customers are feeling.

After the installation of the Cycle Stop Valve, notice that the "heartbeat" has completely disappeared.  The pressure is maintained very close to a constant 60 PSI.  Only a few times during peak demands does the system pressure drop to about 50 PSI.  This will eliminate all the abuse usually suffered by the pump, motor, controls, and check valves, that happens with the big pressure tank system.  The customers on the system will benefit from the "constant pressure" being supplied while the big pressure tank is out for service.

The operator of these systems said they will be using a CSV full time on some systems that have an even worse cycling problem.  Hopefully we will also soon be getting information on the energy use before and after installing the CSV.

1476

Pumps, Wells, Tanks, Controls / Sub Drive "Pulsing Sprinklers"

« on: August 25, 2008, 09:19:49 AM »

A recent installation at a "Smart House" close to Branson, Missouri used a Sub Drive, the home owner called an "on demand" system.   The multi-million dollar house was all computer controlled, and used a Sub Drive system with a 3 gallon pressure tank.  The pump man installed the pump, the plumber installed piping to the house, the electrician wired the system, then the irrigation contractor came in to set up the sprinklers system.

The well head was a couple of hundred feet away from the main house and the mechanical room.  The Sub Drive controller and 3 gallon tank where installed in the mechanical room.  The irrigation contractor teed into the water line in a vault out by the well head.

Problems were encountered as soon as the irrigation system was turned on.  The long distance to the Sub Drive controller, and pressure sensor with a 1 PSI bandwidth, caused the sprinkler system to pulse.  The sprinklers would throw 35', then drop to 20', and the process kept repeating itself over and over.  The pulsing problem at the sprinklers was similar to the pulsing seen on a standard pump system with a water logged tank.

The irrigation contractor had already purchased and installed a CSV at the well head, prior to the tee to the irrigation.  There was no pressure gauge at the well head or on the irrigation system.  The system was still pulsing, so the irrigation contractor called technical support at Cycle Stop Valves.  Without knowing the pressure settings or being able to see a pressure gauge, the tech at CSV recommended turning the adjustment bolt on the CSV counterclockwise one full turn.  The pulsing immediately went away, and the sprinklers began hitting the 35' mark precisely and continuously.

Installing the CSV turned out to be a much better solution than ditching through the yard, and boring a new hole through the house to install the sprinkler line, after the Sub Drive pressure sensor.  It was also not an option to put the Sub Drive controller in the vault, as the humid environment would quickly destroy the computerized electronic controller.  It was also quickly noticed that the CSV keeps the Sub Drive system from pulsing while small amounts of water are being used in the house.  Without the CSV, the Sub Drive pressure sensor was pulsing the pump system 45 times per minute, while a shower or other water use was on.  With the CSV, the pressure remains constant, and the pump does not pulse, while a shower or other appliance is being used.  

The irrigation contractor was very happy with the CSV retrofit of the Sub Drive system.  However, he soon realized that the CSV was doing the "constant pressure" control, and that the Sub Drive itself was no longer being utilized as the main control.  Since the CSV is the only "constant pressure" control that is needed, replacing the Sub Drive controller with a standard controller, will eliminate the "harmonics" and "stray voltage" problems to the "smart house" that can be caused by variable speed control of the Sub Drive system.

1477

Pumps, Wells, Tanks, Controls / Fix Sub Drive with CSV

« on: August 11, 2008, 04:59:03 PM »

They make the Sub drive look very inviting, and it is if it would last. I talked to a pump man in NC the other day who is not having much problem with the Sub Drive, and has some that are over 4 years old. However, his installations are on homes with no irrigation and no heat pump. So when just using water for home use they seem to be lasting a while. I heard from another installer in NM and another in Montana that can’t keep them running six months, because they have irrigation and evaporative coolers making them work more.

Of course you can use the Sub Drive with a regular pressure switch and CSV. There are a lot of people fixing them this way. Then you can use all the draw down from the tank, and the CSV keeps the Sub Drive switch from having to make and break 45 times per minute, which seems to be the essence of their problem. See attached.

1478

Pumps, Wells, Tanks, Controls / Thrust Bearing and CSV

« on: August 11, 2008, 09:59:36 AM »

I am sure it is a shot at me alright. However, they use a lot of "may’s and if’s" to cover there rear. Actually a Kingsbury type thrust bearing is a frictionless bearing. There is a film of water that separates the Stainless disk from the Teflon or carbon impregnated pads. As long as the bearing stays cool, it can easily handle the weight of the shaft, water, and the K factor of the impellers. The motor has to be spinning at least 1800 RPM, to cause the hydroplane effect that forms the film of water between the pads and the disk. Water is non-compress-able, so the thin film of water can hold up tremendous weights. Only if the weight is enough to physically break off a pad will the bearing fail. This is not something that happens over time. If there is too much weight for the bearing to handle, it won’t last 5 minutes. If the bearing can handle the weight, there is absolutely no friction on this type bearing, so it should last many years. Again, it is not something that is going to cause a gradual wear.

Actually it is running below 1800 RPM that destroys Kingsbury type thrust bearings. When the motor starts, there is no film of water on the bearing until 1800 RPM is achieved. Even with the quick start of an across the line starter, there is a portion of a second that the bearing runs dry. When the bearing runs without the film of water, it burns off a layer of the carbon or Teflon. Because this bearing is also what determines the spacing of the pump impellers, it is very height critical. Just a thin layer of material burned off, and not only is the bearing damaged but, the impellers can also drag. The best way to make a Kingsbury thrust bearing last, is to start the motor as fast as possible, and to have as few a starts as possible.

A soft starter or VFD is the hardest thing on Kingsbury thrust bearings. The longer it takes to get to 1800 RPM, the more wear there will be on the bearing. These variable speed units with the very small tanks, must start for every glass of water, or even when the ice maker fills. The more starts, and the slower the starts, the sooner the thrust bearing will fail.

1479

Pumps, Wells, Tanks, Controls / Thrust Bearing and CSV

« on: August 11, 2008, 09:58:21 AM »

How does page 5 relate to the use of a cycle stop valve?
 
http://www.us.grundfos.com/Web/Download.nsf/Pages/BA745A98E1B170E788256F090053405E/$File/LSP-TL-015.pdf


"One such problem can occur when a pump is installed and run in
a situation in which it will produce HEAD in the range of shut-off
pressure (left part of the curve, as shown above). Although the
pump is designed to operate over the full curve, if it does not
produce enough flow the weight of the shaft and the pressure of
the water in the drop pipe is not counterbalanced, causing
possible wear to the bearings in the pump and motor. This can
occur if a valve has been closed down so far that the flow is
greatly restricted or when the pump is pumping water faster
than the well can refill itself."

1480

Pumps, Wells, Tanks, Controls / VFD Power Consumption

« on: August 11, 2008, 09:00:40 AM »

Many VFD articles are typically full of hype or misinformation.  There is no way to make a 100 HP motor pull only 12.5 HP load, and still maintain the head or pressure required. Authors show the formula for the Affinity Law. However, like all VFD salespeople, they fail to use any part of it except the part that reduces the HP by the cube of the speed. The most important part of the Affinity Law is that the head is reduced by the square of the speed. This means that the pump can only be slowed by 10% to 15% at the most, or it is no longer getting water to the surface of the well, or it is no longer producing enough pressure to operate the sprinklers.

Here are a couple of accurate curves that show the relationship between VFD and throttling. Note the line for TDH required, and the minimum speed possible to produce this head. Then you can see that in reality, there is very little if any difference in power consumed by the VFD system and a throttling valve system.

Thanks

Cary

1481

Pumps, Wells, Tanks, Controls / VFD Power Consumption

« on: August 11, 2008, 08:57:30 AM »

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1482

Pumps, Wells, Tanks, Controls / Oregon Nursery loves CSV

« on: August 08, 2008, 11:25:25 AM »

A large nursery in Oregon uses several Cycle Stop Valve to control irrigation pumps.  They have been using CSV's for several years and find that they give excellent control and dependable service.  Recently a salesman talked them into trying a different brand of valve, claiming that a Cyclegard valve was "just like" a Cycle Stop Valve.   A 6" Cyclegard valve by Danfoss Flomatic was installed.  Problems immediately occurred from the speed control needle valve clogging with sand.  Also the reaction time of the Cyclegard valve was too slow, and the pressure switch would bounce the pump off and on.  

Several attempts were made to solve the problems to no avail.  Since the nursery owner had several Cycle Stop Valves functioning perfectly, he ordered that the Cyclegard valve be removed and replaced with an original Cycle Stop Valve of the same size.

The Cycle Stop Valve does not have needle valves, as it does not need speed controls.   The fast reaction time of the Cycle Stop Valve also keeps the pump from bouncing on and off when the  flow rate in the field is changed.  The following is a picture of the Cycle Stop Valve installation and the background shows happy trees receiving a dependable supply of water.

1483

Pumps, Wells, Tanks, Controls / Community Pressure Tank "Exploded"

« on: August 05, 2008, 04:29:55 PM »

A Community Water System in north Texas had a big problem.  Their 15,000 gallon pressure tank blew up.  The pictures do not do justice as they were taken several months after the fact.  The cinder block building containing the pressure tank was completely destroyed.  The end of the steel tank that is missing, actually flew into the overhead electric lines and shorted out the electricity for the entire community.  A newly installed air compressor on the tank that was not adjusted properly is taking the blame.  However, many things can cause a tank to explode.  

Thank goodness it happened in the middle of the night, and when no one was around or it could have caused injury or even death.

Power was restored and the debris was trucked away but, the community was still out of water.  A 15,000 gallon pressure tank is not a stock item.  So it would be several months before a new tank could be procured.  In the interim, a 4" Cycle Stop Valve and an 80 gallon diaphragm tank were used to control the 400 GPM fresh water pump.  The CSV and 80 gallon tank have a combined retail price of less than $3,000.00.  A new 15,000 gallon pressure tank installed is going to cost the community close to $50,000.00.

After several months of working on the CSV with the 80 gallon tank, the community is very pleased with the results.  The pressure is more constant than before, and the electric bill is still relatively the same.  The CSV and small tank were installed in a small adjacent building, so a big building, which will also be expensive to construct and heat, has not needed to be built.

There is an above ground tank that stores plenty of water to be used as needed.  So the supply pump, with CSV, and small pressure tank are required to deliver varied flow rates at a constant pressure.  Of course the CSV does a good job of this, as it can supply as little as 5 GPM in the middle of the night, to as much as 400 GPM during times of peak demand, while maintaining a constant pressure.

There really is no need, and the community does not want to replace the 15,000 gallon tank.  Not only are they afraid of the potential explosive hazard but, they do not want to spend upwards of $50,000.00 on a water system that is working better than ever before.

The problem is, the State of Texas is decades behind the technology available.  I have tried many times since 1994 to explain this technology to State of Texas Engineers, as well as State Representatives.  I don't want to say that they can't understand this simple technology but, they certainly do not care to even try.  I have been told many times that this system looks really good but, legislation would have to be changed before they could even consider it.

In the meantime, huge pressure tanks are exploding, countless gallons of water are being wasted to leaks in the system, and millions of dollars are being wasted on huge pressure tanks and water towers, that are no longer needed.

I wonder if the Texas State officials have ever read the "Mission Statement" that they send out with every licence and document.

                                  The Mission of the Texas State Government

"Texas State Government must be limited, efficient, and completely accountable.  It should foster opportunity and economic prosperity, focus on critical priorities, and support the creation of strong family environments for our children.  The stewards of the public trust must be men and women who administer state government in a fair, just, and responsible manner.  To honor the public trust, state officials must seek new and innovative ways to meet State Government priorities in a fiscally responsible manner".

Texas State Officials DO NOT seek new and innovative ways but, actually REJECT new and innovative ways without justification.  Even though the rules allow for variances to test new and innovative ways, I have been informed in writing that the State of Texas will not issue a variance to try a system with a pressure tank of less than approved size.

What happens now is that when a State Inspector comes by this community water system, it will not pass inspection because of the small pressure tank.  Then the city will have to beg for grant money, as they cannot afford the $50,000.00 + price for a new huge pressure tank.  The system will work as is for several years, while grant money is being procured.  Then tons of money that could have been better used on roads, schools, and other things needed, will be used to return the water system to an outdated control system.  I cannot even give the name of this community or they will be tracked down immediately and forced to spend lots of money reverting back to the old way of doing things.

This is just one of many systems that this has happened to in the last 15 years.  Texas is not the only state which has this problem.  Montana has had plenty of opportunities to test new technology over the years, and still Montana State engineers refuse to come to the 21st century.  

It is public money that our public servants are wasting, because of their lack of knowledge.  Don't accept their standard answer that it is not in the rules.  The rules for the State of Texas were written in the 1950's.  We have come a long way since the 50's, shouldn't our government officials be forced to keep up?  Or do we just continue to let them keep wasting our money and our fresh water supplies?

1484

Pumps, Wells, Tanks, Controls / Three Phase Motors, Single Phase Power

« on: July 30, 2008, 07:42:52 AM »

In Europe there are huge restrictions on the high volume domestic use of the traditional concept of VFD's due to EMI and harmonic controls. Single phase into a 3-phase diode bridge rectifier introduces very high triplen harmonic distortion and this is a key area for the power supply companies and general "energy Efficient building' trend to focus on. It requires large inductors or other mitigation techniques to reduce the harmonics and then there are the filter techniques for the High Frequency interference levels. All the restrictions add huge amounts of cost into the traditional methods of frequency control.

1485

Pumps, Wells, Tanks, Controls / Three Phase Motors, Single Phase Power

« on: July 30, 2008, 07:42:16 AM »

VFDs are being incorporated into a lot of home appliances now. They are just using small 3 phase motors. Most appliance motors are custom made anyway, so they just make them 3 phase. Not a big deal really.