VFD on Pump Stand

[tbarnard]

Hello All,

About 7 months ago I bought my first carwash. Is is just a single bay SS. I have a Cat 310 pump for my wash, wax, and rinse. There are currently no low pressure functions. I only have Rinse, Wash, Wax, and Foam Brush. I would like to add SFR and a Pre-soak. I have a D&S 600 GPD R.O. unit that I got from a friend of mine. It needs filters and a membrane, but he gave it to me for free so I would like to put it to work.

I don't have a lot of room in my equipment room. My thought was if i could put a Variable Frequency Drive on my one pump stand and use just one pump for High and Low pressure products it would save me room and by the time I buy a second pump, plus the starter bucket, plus another circuit breaker, plus wiring it in, plus control wiring, plus plumbing... well you get my point. Would it be easier / cheaper to just put a Drive on my one pump now? My day job is Programming and Installing Commercial temperature controls, So i spend a lot of time around VFDs. If anyone has done this i have a few questions.

1.) Can you put a VFD on a Cat 310 pump. Will slowing it down make less pressure without adversely effecting the operation of the pump.

2.) I only have single phase power. Can a get a drive that i can feed 220/single phase into and run a 208/3phase motor?

3.) Do i need to oversize the drive if i only feed it single phase power or do they may specific drives for single phase input?

Thanks guys.

Tyler

 

[mjwalsh]

1.) Can you put a VFD on a Cat 310 pump. Will slowing it down make less pressure without adversely effecting the operation of the pump.

2.) I only have single phase power. Can a get a drive that i can feed 220/single phase into and run a 208/3phase motor?

3.) Do i need to oversize the drive if i only feed it single phase power or do they may specific drives for single phase input?

Thanks guys.

Tyler

Tyler,

I believe Kustom Kraft did something similar. It seems like our friend Tom Hoffman of New York has done a quite a bit with VFDs & who can attest to the long term practicalities etc. I have been told the capacitors usually have a 10 year life --- maybe someone can shed light on that.

I am not sure on the 1st question.

For sure you can do what you are wondering about on #2.

To answer #3 the single phase input VFDs for sure are available in the 3-5 HP range that you will need for your Cat 310.

During the last 7 months we have actually gained actual installation & programming experience with 3 of the Hitachi WJ200-022Fs which is just one of many brands. The experience is still a work in progress & relates to some very high inertia centrifuges. I suppose the 2 projects would have some common concerns. It will be nice to find out what kind of enclosure you have in mind for the VFD that you choose. We got our drives from driveswarehouse.com & Eddy & Darrin were not too bad to work with.

There is 420 pages in its instruction manual --- so there is a bit of a learning curve. You would have to have a 24 vdc controller that would output to the VFDs intelligent terminals. Some 24 vac signals from the coin box would have go into that specific controller --- unless someone else has another approach.

Be sure & share what you come with as to some of the technicalities the rest of us might overlook in doing something similar.

Mike

 

[MEP001]

In my opinion you'd be better off doing it the "old-fashioned" way, i. e. separate pumps for each application. Yes, a VFD will work and do what you want, the difference in cost is huge. You need at least as many solenoids to do it either way, so one or the other isn't less complicated. There are other things to consider, such as the purge time for the high-pressure line to the bay for the RO. thoffmanjr has systems that sound like they work well, but it purges the line to the drain which seems both complicated and wasteful.

 

[tbarnard]

Thanks for the replys guys, Hopefully some of the members here that have this operating in their own setup will chime in.

I did call Cat Pumps today to ask them about it. The guy in their technical support department that i talked to said that putting a VFD on the motor and slowing the pump down will NOT give me the results I am looking for. He told me it slowing the RPM down will only slow down the water flow not the pressure. I am a very mechanical person and work with commercial hydronics (heating and cooling systems) almost daily. I don't see how changing the pump from 4 gpm to 1.5 gpm when pushing the water thru the same size tip on the wand will not lower my pressure as well. I am not following his thinking, unless there is some difference between plunger pumps and centrifugal pumps I don't know about. He suggested instead that I either 2 pump it (as Mep001 says "the old-fashioned way" I like that) or suggested that if i changed the size of the tip (bigger hole) that I could get less pressure. That if I would put a quick connect tip on my wand then switch to a much bigger tip that would lower my pressure. I explained that I'm almost certain in a small farming community, which I'm in, that the farmers would get themselves a new tip for their hog barn washing Pressure washer with every visit to my car wash. He then said, yeah i guess you're right. "I don't know how they switch from low to high pressure at carwashes then."

I have given some thought to maybe pluming in a Tee off the discharge of my Cat 310. Run one side thru a pressure relief valve set at 1350 psi for my high pressure wash/rinse then thru a check valve. The other side of the tee would go to another pressure relief valve set to 600 psi for my low pressure SFR/presoak then thru a check valve to another tee to join up with the 1350 psi side then out to the wand. Use solenoid valves to switch between the two.

The only problem with this is I cant seem to find a 4 gpm solenoid that is rated for 1400 psi. I would actually like to use a 3-way so it if power to the solenoids fails at least one way would fail open. The closest I can find for this is a 3-way 120vac solenoid that is for hydraulic systems.

Can a guy run water thru a fitting that was designed for Hydraulic oil?

I will probably go the "Old-Fashioned way" eventually, but as a young, energetic entrepreneur, I am looking for other ways. But maybe everyone runs 2 pumps for a reason.

 

[Waxman]

Use a separate pump. Spend the entrepreneurial energy figuring out how you're going to make any money with one SS bay.

 

[MEP001]

A lot of washes I've seen that use the high-pressure pump for the RO use a Dema 453P solenoid and two bypass regulators to control the pressure. The solenoid opens to allow flow to the second regulator set to a lower pressure, and an Erie Motortrol valve switches the inlet from the usual gravity feed tank to the RO.

 

[ken-pro]

Slowing down a positive displacement pump (Like your CAT310) will only reduce its volume output. The pump is still technically able to build pressure to its maximum PSI based on the regulator setting.

ie: If you slow down the pump to 15 Hz, it will run at 1 GPM. At 1 GPM with a #7 tip, you will generate aproximately 250 PSI. HOWEVER, if the tip plugs or the customer closes the trigger, the pressure will build up to either the maximum it can generate at that volume OR until the regulator opens at its setpoint.

What you need is a VFD, an analog pressure transducer, and most likely a PLC controller with suitable program.

This gives you a closed loop system where you know both the motor RPM and the output pressure. This allows the system to automatically regulate motor speed to maintain the proper pressure output for the particular flow requirement. Without this when the customer releases the trigger while running a low pressure function, the line pressure will increase substantially. When the customer pulls the trigger again there will be a momentary high pressure blast before the pressure settles back down to the correct setpoint.

As MEP suggests, using a high pressure solenoid valve, and a regulator is a much less expensive way to do this.

 

[sparkey]

I know Allen Bradley makes a drive that will take a single phase input and give you a 3 phase output. I would think others would make them too. Variable frequency drives actually take the input power and convert it to a high voltage DC buss (over 700 VDC if you are driving 480 volt motors) then chop the DC buss signal to control the speed of the motor.

Another thing to consider is not all motors are made for use on inverter drives. Sure any motor will work, but you may dramaticly shorten the life of your motor. At slow speeds the motor looses its cooling ability due to the fan running slower and with an inverter drive the motor is seeing a lot higher voltage spikes than it normally would. Inverter duty motors typically have class "F" insulation which you should be able to see on your motor name plate.

VFD's can also cause harmonics on your power lines if not installed with a line reactor. A line reactor has to be purchased seperately. On the plus side a good drive has a better power factor than just running a starter on a motor. I was in an AB class last spring where AB said their drive ran at a power factor of 1, which is perfect.

As far as the pressure thing. I remember from hydraulics class the instructor stressing on a daily basis.. "Pumps create flow not pressure". Pressure is created from restrictions. I can see how letting off the gun trigger would create more of a restriction cauising the pressure to rise.

 

[tbarnard]

Thanks Mep001, Ken-Pro, and Sparkey. I appreciate the reference to the Dema 453P. I could not find such a valve just doing a little seaching.

I guess I'm impressed that you guys are willing to have an adult conversation about how to solve a problem, what alternatives there are, and are willing to share what you have picked up thru your years of dedication to the car wash industry.

Spend the entrepreneurial energy figuring out how you're going to make any money with one SS bay.

Seems a little salty. I didn't buy a 1 Bay SS 2 blocks from my house in a town of 350 people thinking that I would be able to quit my Full time job and retire off it's income at age 28. I don't own multiple car washes in a metropolitan area, and don't spend 50 hours a week at my wash. I do stop there seven days a week for 15 to 20 min. to rinse down the bay, check equipment, trash, and vacuum. I turn to people who do spend much more time at a wash for advice and direction. Not cynical comments about the size of my first business.

 

[mjwalsh]

If you slow down the pump to 15 Hz, it will run at 1 GPM. At 1 GPM with a #7 tip, you will generate aproximately 250 PSI. HOWEVER, if the tip plugs or the customer closes the trigger, the pressure will build up to either the maximum it can generate at that volume OR until the regulator opens at its setpoint.

What you need is a VFD, an analog pressure transducer, and most likely a PLC controller with suitable program.

Without this when the customer releases the trigger while running a low pressure function, the line pressure will increase substantially. When the customer pulls the trigger again there will be a momentary high pressure blast before the pressure settles back down to the correct setpoint.

As MEP suggests, using a high pressure solenoid valve, and a regulator is a much less expensive way to do this.

tbernard,

As usual Ken-Pro brings great light to an issue when he is familiar with something.

We have been using the following dump gun with what we feel great success: http://www.kleen-ritecorp.com/p-1253-kleen-rite-dump-gun-w-12-lance-handle-10gpm-3000psi.aspx I think these guns offer advantages regardless of the VFD. By squeezing less the customer has less pressure --- variable pressure if you will. Also a plug just in the more likely tip --- will not cause the bypass to get hot like the way many systems will do.

It seems to me that this would 100% solve the pressure change isssue more than satisfactorily with more simplicity & less expense.

I remember some very favorable posts on Kustom Kraft's equipment if you do a search --- are they using a PLC &/or duplicate regulators? It seems like they also were using cog belts --- which is probably irrelevant to the VFD use.

Mike

 

[MEP001]

We have been using the following dump gun

The whole idea here is to reduce the pressure at the pump to run spot-free rinse to the bay. The dump gun reduces the pressure by literally dumping all the flow through the wand, and is completely impractical and irrelevant to this issue.

 

[mjwalsh]

The whole idea here is to reduce the pressure at the pump to run spot-free rinse to the bay. The dump gun reduces the pressure by literally dumping all the flow through the wand, and is completely impractical and irrelevant to this issue.

VFD --- Cat 310 experts,

Why would it be completely impractical & irrelevant? The issue as I understood it was uneven & unexpected pressure. If the specific wand used allows flow as if there was no nozzle on it when not squeezed is relevant!

There would be like Ken-Pro described as I understand it a maximum of 215 psi - 1 gal flow at the VFD's 15 hz based on the #7 nozzles size with of course the dump gun being in its normally squeezed position so it is routed just through the #7 nozzle. From experience this seems like a suitable rate for RO & possibly other low pressure functions.

For the hi pressure functions the VFD most likely would be run at 60 hz. --- which would be of course be somewhat less the desired hi pressure & more gpm if the trigger was not squeezed all the way.

Unless, I am misinterpreting what Ken-Pro described ....

To say there is no value in my suggestion of possibly further simplifying the previous suggestions & does not merit further technical discussion --- does not make any sense at this point in the unfolding discussion process --- to me at all!

mike walsh king koin of bismarck

 

[MEP001]

The whole point of this thread is about how to reduce the pressure AND THE FLOW from the normal bay tip to the gun, presumably down to around 200-400 PSI. A dump gun releases all the flow around the tip with no pressure at all. Would you have your customers using spot-free rinse at 3 or 4 GPM out the end of a gun with no tip in it? What you're suggesting is the same thing.

What ken-pro is saying is that leaving the pump at its current configuration and just reducing the speed of the motor when spot-free is selected means that when the trigger is released the pump will still be running at 1000 PSI due to the reduced flow at the gun. I don't believe that would be much of a problem since it does that anyway, but if one goes the route of a pressure transducer and PLC one could eliminate the regulator altogether and let the VFD control the pressure.

 

[tbarnard]

I had another gentleman tell me that I probably do not want to run RO water thru my 310 because he has heard of issues where the RO water will eat away at the metal in the pump. I don't know if this is true or not.

I guess at this point I'm debating whether i should set up a second pressure relief valve off of my single 310 and use on relief valve set at 1350 and one set at 600 or if i should go to a second pump.

If I decide to use a second pump what are my options? Again i want to run SFR and presoak at lower pressure. Am I better off using another triple plunger pump turned down or some other type of pump. Pneumatic pumps will not work as i only have a small compressor that provides only air for foaming my foam brush it needs to be an electric pump. I would like to be somewhere around 500 to 600 psi at the wand for low pressure functions.

Thanks again guys.

 

[MEP001]

The most common way to get RO to the bay is with a Procon pump. The motor, pump and coupler will run as much as $600 depending on where you buy them. It's fairly compact and will run maximum 250 PSI. It would actually be cheaper to run it through the high-pressure pump with the setup I described, and you can give more pressure. We're running a Cat 390 pump for the RO to the bays at 450 PSI and cusomers really like the higher pressure.

I've heard the same thing about RO through the pump manifold "eating it away" but I've never seen any evidence of it.

 

[mjwalsh]

Would you have your customers using spot-free rinse at 3 or 4 GPM out the end of a gun with no tip in it? What you're suggesting is the same thing.

tbarnard,

Clearly, that is not what I am suggesting --- & I would be very surprised if the 15 hz to the motor on the pump would actually flow that much RO water like Mep describes.

What Mep described as what I referred to I do not believe is going to happen with the dump gun. It would behave the same when the customer squeezing the trigger as the regular gun would. That is what counts. The other state of the trigger would almost be a total non issue unless the customer did not want any pressure at all --- which is unlikely or if they left the gun run free in the holder wasting their paid for time???

When the customer releases the trigger that means the customer doesn't care about the pressure & it would be highly unlikely they would use it in that way. I doubt it if there would be an increase to anything more than a half gallon more of RO without the nozzle restriction effect --- based on my understanding of what Ken-Pro said of the 1 gallon in the 15 Hz state.

My take is that Mep is speculating about the increase from 1 gallon clear up to 3 or 4 gallons because the nozzle is being bypassed ---- causing waste of RO or whatever at the 15 hz.

I am not saying that my way has been tested or is as thorough as what the other guys are referring to & the regulator may be needed for other reasons ---- but based on experience & what Ken-Pro seemed to say about the change in pressure & volume from the 60 hz to the 15 hz I would say it might be worth a quick test. We do have a missing piece of information in terms of: Did Ken-Pro suggest that there would be only one gallon also at the high pressure 60 hz?

Hopefully, Ken-Pro or someone who has actually observed the difference in volume when both the nozzle status & the hz changed --- what actually happens.

I do agree with Mep about the Procon option --- that is what we use.

I am not saying that what I suggest is not an oversimplification --- I am saying that it should not be ridiculed & not even considered unless it was tried before somewhere & proven to not work like I describe.

mike walsh king koin of bismarck.

 

[mjwalsh]

Yes --- More Relevant Considerations on the Table - Isn't This Exciting!

tbernard,

Hopefully these links relating to Custom Kraft will help.

http://forum.autocareforum.com/showthread.php?t=3306

http://forum.autocareforum.com/archive/index.php/t-1139.html

One significant advantage to the Pressure Transducer & the PLC like Ken-Pro suggested is that you probably do not want all your low pressure options to have the same flow & pressure as the RO.

When we did our very recent dog wash PLC --- since we now had the extra PLC capability at that point --- we used an air pressure transducer with the PLC to fine tune the make up air needs for our connected laundromat.

It sounds like you are already a gifted programmer --- so my guess is --- unless the water pressure transducer cost is out of sight --- the Transducer-PLC approach could be the best. On the single phase 3-5 HP Sensorless Vector VFDs that I am working with --- they have 7 intelligent inputs that you could utilize.

After a bit more thought --- I am thinking you could possibly simplify by not using a PLC & just make sure 24 vdc goes to the relevant specific preconfigured VFD intelligent input. Car wash like HVAC tends to be 24 VAC so that could be a slight issue.

Sparkey mentioned a line reactor --- we could not find a AC line reactor for the 3-5 HP single phase VFD that we used. We were told it was more relevant to the 3 phase input version. There has been no sign of harmonic line noise created from the VFDs being a problem at this point for us. We tested our VFD in our back garage for few months & 2 of them have been on line for public use for about 2 weeks now.

A true RMS voltage meter could be useful at some point with the VFD. We are tempted to invest in one --- so we have more accurate info during a potential troubleshooting event on the final output side of the VFD to the motor.

I was amazed at the significantly lower amperage readings that showed on my clamp around amp meter compared to the amp readings running the same motor without a VFD --- just to give you a heads up on another potential benefit of going the VFD route.

I had a wise engineer friend who told me once upon a time that --- if you can't do it on a pre-done plan --- there is a good chance it can not be done at all. So --- how are your drafting skills?

mike walsh king koin of bismarck

 

[MEP001]

The whole point of reducing the pressure for the spot-free to the bay is to reduce the amount of water the customer is using. Since historically the RO reject is dumped down the drain, for every part the customer uses two more parts are used. The point of this thread and the customer's use of RO in general is NOT to control the pressure THEY want but to control the AMOUNT of water they get. I would MUCH rather just run the RO to the bay through the pump at high pressure than use a dump gun.

 

[tbarnard]

tbernard,

It sounds like you are already a gifted programmer --- so my guess is --- unless the water pressure transducer cost is out of sight --- the Transducer-PLC approach could be the best. On the single phase 3-5 HP Sensorless Vector VFDs that I am working with --- they have 7 intelligent inputs that you could utilize.

After a bit more thought --- I am thinking you could possibly simplify by not using a PLC & just make sure 24 vdc goes to the relevant specific preconfigured VFD intelligent input. Car wash like HVAC tends to be 24 VAC so that could be a slight issue.

I was amazed at the significantly lower amperage readings that showed on my clamp around amp meter compared to the amp readings running the same motor without a VFD --- just to give you a heads up on another potential benefit of going the VFD route.


mike walsh king koin of bismarck

Mike,

I did a quick search on the web for a Endress-Hauser pressure transmitter that is rated to 1500 psi. Looks like the price is about $300. I have used Endress-Hauser stuff before. It is good stuff. I haven't really searched for any other stuff. Could probably find cheaper, but it looks like it is probably an expensive sensor.

I think i would just use relays to enable the different speeds on the drive. Every drive i have worked with (ABB, Allen Bradley, Danfoss, Yaskawa, Square D) all have a 24vdc source terminal. If connect that terminal to the correct digital input the drive follows that input. All of our HVAC controls equipment is 24vac. We always use a 24vac relay with the coil driven off of an output with the com terminal of the contacts on the 24vdc and the N.O. terminal of the contacts on the start/run digital input.

I'm not sure just setting the pump motor to 36 hz, for example, will yield the desired results. As someone mentioned before, it will as long a the customer keeps the wand trigger pulled, but if they let off the pump may build up to the unloader pressure set at 1350 psi. So they will get a quick 1350 psi blast when they pull the trigger again, then it will settle back down.

I did get on Custom Krafts website and request a quote. It will be interesting to see what they reply with.

The second unloader / pressure relief valve tee'd in is looking quite tempting based on cost alone.

Thanks again.

 

[mjwalsh]

If it can be kept as simple as possible & still work --- why not?

Tyler,

If you use the dump gun that we happen to have always used which has something to do with why we prefer them --- the behavior will be the opposite of what the regular trigger gun will do. When they let up the trigger the pressure will be less.

I am basing my thinking that the 2nd unloader & even the tranducer could possibly not be needed if the dump gun is used because then the burst of high pressure --- as if regular shut off gun is used won't happen.

I could be wrong but it seems like an opportunity to simplify things. With all due respect to Mep --- I am thinking the hz also lowers the volume which is what he is rightly concerned about of that specific need for the lower pressure & medium pressure options. It seems like the intelligent terminals can receive a signal for the appropriate hz that will hopefully produce a satisfactory volume-pressure good fit for that specific selection by the end user customer.

I see another consideration that going too low on the hz for the presoak & tire motor or other lowest pressure-volume selection --- may not be compatible with a minimum speed the Cat 310 may require??? I am not sure if that is an issue but it should be ruled out.

It would be nice get a better handle on the exact hz or pump speed's relationship to the volume both when the dump gun trigger is pulled (nozzle only) & when it is not pulled (as if there was no nozzle at all) We know that the pressure as Ken-Pro stated with a gun that actually shuts off --- requires the unloader-regulator to keep from blowing off the pump head is still needed even at the lower hz. Even with the dump gun a needed bypass with at least one unloader-regulator is still needed in case of a frozen dump or plugged dump gun.

I agree with Mep that without the restriction there will more volume output than with the nozzle & shutoff style of gun --- what needs to be done is to find out if those very brief moments of increased volume is excessive enough to be concerned about using the dump style gun. That would be worth verifying with an actual experiment besides just going by a Cat 310 pump curve chart that Cat or Arimitsu should be able to provide.

mike walsh king koin of bismarck