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Webtrol H10B8SS Pump Question

Webtrol H10B8SS Pump Question

Webtrol H10B8SS Pump Question

(OP)
Looking at the literature for the Webtrol H10B8SS Pump it states the pump works best in the 8-10 GPM range and will max out at 18 GPM.

My problem, The pump is producing 14-15 GPM and I cannot seem to get the pump down to the 8 GPM range. Any questions or suggestions appreciated.

RE: Webtrol H10B8SS Pump Question

Since you probably have little discharge pressure, the pump is "running out" on the pump curve. More piping headloss will force the pump to pump at less flow.

You can add a valve on the discharge side to throttle the pump back. Or you can add a VFD on the pump.

RE: Webtrol H10B8SS Pump Question

All you need is an 8 GPM Dole valve.

RE: Webtrol H10B8SS Pump Question

(OP)
Ok, I have taken this system over from a competitor so I don't know how many feet are in the water loop. There are apparently no drawings of the system from the previous tenant as well. I have spoken with Webtrol today and they state the Dole valve is the way to go.

I have a few questions though.

Running the pump today after purging all the air from the closed loop piping, the pump operated at 14 GPM.

After the discharge side of the pump it feeds a two banks of Mixed bed tanks, size 8"x44" in paralell (2) tanks each bank, then feeds a UV Unit 1' in and out, then a 30" 0.2 micron filter ,,,, (ALL PIPING IS 1" SCH 80 PVC)

The problem -- The pressure across the filter is only 20 PSI ,,,, How could this be?

Also, would it be wise to install a 1" Flowmeter after the 30" filter housing on the distribution side of the loop?

For that matter, also install a flowmeter on the return?

There is ample room for both.  

 

 

RE: Webtrol H10B8SS Pump Question

One would think that you would be interested in a valve designed for ultrapure water applications such as the Asahi valve:

www.asahi-america.com/.../O&M%20Constant%20flow%20valve.pdf

Not all valves are suitable for ultrapure water applications.

Since the flow meter is installed in a loop, there is no reason to install 2 flow meters.

PVC piping is not suitable for ultrapure water applications.

RE: Webtrol H10B8SS Pump Question

(OP)
I realize PVC is not the best suitable pipe for DI water but hey, what can I do? The pipe loop was installed to the labs long before this recent tenant took over the space. The date codes on the Webtrol pumps are dated October of 1989. This system has been been in place for quite a while.

My main and ONLY concern at this point is my flow rate and the consequences on the Deionizers, UV unit and final filter.

When I took over the system I mirrored everything that was already in place. The reason being, there are NO known drawings of the pipe loop in existence. Also, I found old paperwork lying around showing the Deionizers were replaced back in 06, so I replaced those tanks (the old were still connected) with my tanks of the same size and media depth.

BIG problem, the Webtrol is pushing out 14 GPM but the tanks are only rated at 5 GPM ,,, I'm worried the extreme flow rate is going to: 1) Destroy the tank internals.  2)Pack the media beds. So I definitely NEED to throttle back the flow rate after the pump,,, agreed?

The Dole Valve does come in stainless from the literature I've read ,,,, It should work ,,, no?

Another thing just so I can understand.

If I'm restricting the fow rate after the discharge side of the pump with a valve to achieve say 5 GPM, How is the suction side of the pump effected? The suction side of the pump is fed with both direct city feed pressure (65 PSI)as well as the return from the loop.

 

RE: Webtrol H10B8SS Pump Question

For your application, restricting the discharge side of the pump will have negligible effect on the suction side.  

RE: Webtrol H10B8SS Pump Question

(OP)
"For your application, restricting the discharge side of the pump will have negligible effect on the suction side."

Just so I'm clear then,

The Dole Valve will be installed after the flow meter on the discharge side of the pump. Yes?

If I install a 5 GPM rated Dole Valve, Should the Flow meter after the pump never read any higher than 5 GPM?

RE: Webtrol H10B8SS Pump Question

Correct. The flow should be approximately 5 gpm.

RE: Webtrol H10B8SS Pump Question

(OP)
Another theory.

There is a booster pump and bladder tank on the feed to this system feeding the Webtrol pump.

Is it possible that the booster pump regulates the flow?

There is a check valve pointing in the direction of the pump. Could it be possible that when labs draw water from the loop the pressure on the Webtrol would drop and then the booster pump would kick on to bring the pressure back up? ,,, Then once the pressure is attained the booster pump would shut down ,,, and repeat the cycle when the demand is called for again?

The reason I ask is I may have missed this entire part of the equation. It seems to me the original tanks (competitors I removed) are EXACTLY what I have replaced and are rated for 5 GPM ,,, it seems to me the competitor would not have put in 5 GPM rated tanks with a 14 GPM flow rate.    

RE: Webtrol H10B8SS Pump Question

Perhaps you can put a sketch on eng tips so that one can understand the system.

The typical water loop has an inlet, pump, treatment device, and a discharge point. The discharge point probably drains into a tank.

The flow through the loop is most likely controlled by a PRV located at the discharge point.

RE: Webtrol H10B8SS Pump Question

I was thinkg that you would sketch a diagram with the components such as valves, pumps, tanks, etc. Alternatively, you can label the components on the pictures.

My last post should have said backpressure control valve instead of PRV.

RE: Webtrol H10B8SS Pump Question

(OP)
OK, I'll give that a try. I don't like the fact there is no edit feature in the forum. Perhaps a moderator could please delete the photos I've posted?

RE: Webtrol H10B8SS Pump Question

(OP)
OK. this is a very crude drawing, it deals with direction of flow for the pumps. The feed water is at the top of the picture. Follow the arrows if possible. The two PRV???? on the pumps are my concern. One is for the incoming water the other for the return. I'm lost. Are they supposed to balance the loop?  

RE: Webtrol H10B8SS Pump Question

If you put the picture into a word file, you can add labels to items in the picture.

RE: Webtrol H10B8SS Pump Question

(OP)
Ok, between this post and my last post we should have a pretty clear understanding of the water routes and components. Now hopefully we can get together and figure it out. Again, my main concern is the pump putting out 14 GPM yet I'm only showing 20 PSI on the final filter and my return pressure at the pumps is less than 10 PSI ,,,   

RE: Webtrol H10B8SS Pump Question

Do you have the pump head curve?

The return line from the building loop should have a backpressure valve not a PRV. A backpressure valve will retain the pressure on the inlet side of the valve.

A PRV is a different type of valve that is used to reduce the pressure across the PRV, not retain the pressure.

One would think that the users on the building loop would be complaining about the low water pressure.

RE: Webtrol H10B8SS Pump Question

(OP)
Question. How would I be able to know if the valve in place is either a PRV or a back pressure valve?

There are no markings on either valve. (the one from the feed source or the one that returns to the pumps)

I take it you were able to figure out the layout from what I posted?

RE: Webtrol H10B8SS Pump Question

The valves should have a manufacturer's name and part number on them.

The flow meter is reading the recirculating flow around the pumps. It looks like there is a PRV on the recirculating line after the probe and before the temperature gauge.

A minimum flow of 30% is the usual recirculating flow for this type of pump arrangement. The recirculating flow is to prevent the pump from dead heading when no users are drawing water.

A flow meter should be installed in the building loop to determine the flow through the loop. There is no way for you to know the flow through the loop without it. You can estimate the flow by subtracting the flow on the pump curve from the recirculating pump flow.
 

RE: Webtrol H10B8SS Pump Question

(OP)
I'll take another look at the valves.

(It looks like there is a PRV on the recirculating line after the probe and before the temperature gauge.)

Are you referring to the valve at the low point in the picture or the valve to the top tight? ref: Pump picture

Also, should it be a PRV or back pressure control valve?

You would recommend a flow meter to be installed after the final filter as the pipe runs up the wall to feed the labs ,,, correct?

I am trying to find a pump curve schematic. I do know the feed pressure to the pumps is 65 PSI and we're recirculating at 14 GPM. - attached are some specs for the pump.

On another note: You can't realize how I appreciate this help.

   

RE: Webtrol H10B8SS Pump Question

(It looks like there is a PRV on the recirculating line after the probe and before the temperature gauge.)

I am referring to the device after the TEE where the piping turns upward  and then turns right toward the temperature gauge. The device shoulg be an automatic Pump Recirculation Valve.

You will not know the flow in the loop unless you have a flow meter on it.

RE: Webtrol H10B8SS Pump Question

You should not have a pressure relief valve. A PRV is device that is used to prevent overpressurization of equipment. A PRV should not operate under normal conditions, only during emergencies. The PRV releases to the atmosphere. You probably do not have a PRV.

The back pressure control valve is an operating valve.

What you have is probably a pressure regulating valve:

http://www.plastomatic.com/pr.html

RE: Webtrol H10B8SS Pump Question

It looks like a pressure regulating valve. I would try a small adjustment and see what it does.

To measure any the results of an adjustment, you need pressure gauges and flow indiators on the loop.

RE: Webtrol H10B8SS Pump Question

(OP)
Should I crank the valve on the return in?

RE: Webtrol H10B8SS Pump Question

I would think that you crank the valve tighter. Don't make a major adjustment. Try one turn and see what happens.

RE: Webtrol H10B8SS Pump Question

(OP)
Probably returning there tomorrow. So which valve? The one on the return line?

I did bypass the final filter the other day, it plugged.

RE: Webtrol H10B8SS Pump Question

If you throttle the reutn line, the loop pressure should increase.

RE: Webtrol H10B8SS Pump Question

(OP)
OK ,,, I'll crank it in on the return. That shouldn't starve the pump in any way right?

So what purpose do you suppose the other valve serves?

 

RE: Webtrol H10B8SS Pump Question

Not really, your water is flowing in a loop.

RE: Webtrol H10B8SS Pump Question

bimr, well done for keeping with this. It's getting exciting now, hop PurewaterGuy posts the reults of his adjustment.

RE: Webtrol H10B8SS Pump Question

(OP)
I'll be going there Tuesday to make the adjustment. I still have questions but don't want to overburden the answerers with them with all the questions at once.

I also have an idea of scrapping the two pumps altogether and going with a jet-pack style pump. I've looked at a good number of faucets there and all seem to be a dead-leg situations. There may be no need to recirculate this loop, I'm thinking along the lines of point of use applications and installing equipment where critical application is most needed. (clean up the water at POU) rather than toy with a PVC loop with dead-legs that will never meet Pharmaceutical spec to begin with.

Good idea?

RE: Webtrol H10B8SS Pump Question

I would prefer to keep the loop and add the PO.

RE: Webtrol H10B8SS Pump Question

(OP)
I got a call of no water in the labs.

Checked out the system when I arrived and the pump flow gauge still read 14 GPM. Checked the labs - No water -

Went to the valve and made one revolution on the screw. Watched the pressure gauge on the return to the pump and it increased 10 PSI.

Returned to the lab opened the faucet and had water and air.  Returned to the system and the flow gauge was fluctuating between 6-8 GPM. Possibly due to air?

Left a faucet open to purge the air from the loop. Instructed them to purge for 30 minutes and turn off faucet.

Waiting for call on flow gauge. I'm going back tomorrow either way.  

RE: Webtrol H10B8SS Pump Question

(OP)
The pump is putting out 8 GPM now. That is the best flow-rate according to the Webtrol technical department. The flow at the faucets is good - even though there is no flow meter within the loop to know the actual flow -

The one revolution on the return valve must have created the back pressure on the loop and at the same time brought the flow-rate on the pump to where it should be .. Agree or disagree with this?

I don't understand what the other valve does? What purpose does it serve?

RE: Webtrol H10B8SS Pump Question

The other one probably controls the water pressure entering the loop from the raw water side.

Without that valve, one would think that the pressure in the loop would rise to the same pressure as the raw water.

RE: Webtrol H10B8SS Pump Question

(OP)
You've been a great help here and I really appreciate that.

Now for the hard part. I really gained nothing on my final filter for pressure. At Initial start-up I got 10-20 PSI. Do you think in order for me to gain greater pressure across the filter I should throttle the return valve even more? This would create greater pressure in the loop correct?

BUT, if I do that it will obviously have an effect on the pump flow-rate as evidenced by the adjustment I just made in which the pump flow-rate dropped to the much more desirable 8 GPM.

Do you think it would be wise to also turn in the screw on the valve for the raw water entering? I'm inclined to believe the two must work as some sort of balancing act (so to speak) Do you follow me here?

Yet another thing, the quality of water (I'm providing 18 meg) is down to 15 meg currently. What type of havoc do you suppose the PVC pipe loop is creating pertaining to the water quality?

I hope you can take the time to answer each of these questions.  

 

RE: Webtrol H10B8SS Pump Question

Are you asking about pressure drop across the filter? The final filter should not have much head across the filter unit because your water is essentially particulate free. I do not think it is advisable to have greater head loss either. You have a greater risk of filter breakthrough. The head loss should not increase much during the run either. The filter should be periodically backwashed or replaced depending on whatever type of filter that you have.

If you are talking about a need for greater pressure in the loop, then you need to adjust the valve more. That will restrict the discharge from the loop and the pressure will rise as the pump operating point moves left on the pump curve. This operating step is a balancing act because if you restrict the flow too much, the loop users will run out of water even though the water pressure is higher.

The valve for the raw water entering should be set for slightly more than the total capacity of all of the loop users combined plus 5 GPM (minimum flow in a 1" line). It would be helpful to have a flow meter on the line for monitoring.

If you only have 15 Meg water, you probably should install a mixed bed cartridge in the loop to polish the water. This would use non-regenerable mixed bed resin and you should run the mixed bed at a flow rate higher than the flow rate for working mixed bed units. Since there is so little material in the water, this mixed bed will run for an extended time.

I don't think that the use of PVC would drop the water quality that much.
 

RE: Webtrol H10B8SS Pump Question

(OP)
The final filter is a replaceable 30" 0.2 Micron with 222 O-ring.
The filter pressure brings me yet another question. If the pump is rated at 8 GPM for best performance, wouldn't you agree the loop was most likely designed for the flow-rate I have going through it now? I realize there is no flowmeter for us to know the true rate. I will install a flowmeter, I have selected this Blue White Flowmeter with 1" connections.

Question regarding the "total capacity of all loop users plus 5 GPM" ,, If all the faucets are the same, If I know the maximum output of one faucet, then multiply by the number of total faucets, will this give me the maximum output?

As for the mixed beds, I currently have a total of 9.6 cubic feet of mixed bed resin inline. Granted 4.8 cubic feet is on the feed side but it still enters the loop feeding into the post pump side where it is polished by another 4.8 cubic feet. (The system drawings show this)

I don't understand why the quality would drop so fast. Perhaps I am getting a chloride breakthrough at the carbon tanks? Thoughts.

Or perhaps the water is not recirculating at a rate that I am getting the full benefit of the tanks. Perhaps channeling is taking place?

As  

RE: Webtrol H10B8SS Pump Question

It seems reasonable that the pump was sized at a lower gpm, not the maximum 14 gpm.

Correct, if you add up all of the faucets plus add the minimum flow in the line will give you the maximum output. You need more flow than the total of all faucets so that the loop will continue to flow when all faucets are open.

If you are not getting 18 meg out of a mixed bed, there is a problem and you need to change the resin. You should be using non=regnerable resin.

The breakthrough from a mixed bed is not chloride. The breakthrough will be in the form of ppb Sodium Hydroxide.

It is possible that you may have channeling, but that is unlikely.

 

RE: Webtrol H10B8SS Pump Question

(OP)
"plus add the minimum flow in the line"

How would I know what this is?

If I experience chlorine break through after the carbon tanks it will make the mixed bed deionizers work harder during the exchange process, correct? That has been my past experience.

I don't buy the channeling either but thought I'd throw it out there anyway to cover all the angles.

Why do you think I should be using virgin resin as opposed to regenerated? There are draw-backs to virgin resin.

RE: Webtrol H10B8SS Pump Question

Mminimum flow is that flow that will provide 3-4 ft/sec flow velocity.

It is probably impossible to get chlorine breakthrough through the carbon filters. Assuming that the carbon filters are correctly operated.

Virgin resin will provide you the best quality water and will not contain any of the regeneration products or leakage. There is some inefficency in regeneration of mixed beds. Thus the water quality will not be as good from a mixed bed compared to virgin resin.  VIrgin resin has cation resins and anion resins regenerated separately and then the resins are intermixed.

RE: Webtrol H10B8SS Pump Question

(OP)
"Minimum flow is that flow that will provide 3-4 ft/sec flow velocity."

Wouldn't it be necessary to know the pipe length and diameter in order to calculate this?

If so, I have no schematic of the pipe layout, how would I achieve this?

I have always had a very high success rate using regenerated resin. So long as it reaches spec after regen at the plant.

Virgin resin is not good for applications, so I am told. Specifically in dialysis applications due to the release of Amines. Have you heard of this?

RE: Webtrol H10B8SS Pump Question

(OP)
I know what the guidelines are for Dialysis. It all falls under RD52 ,, In 15+ years I've never failed to meet the AAMI water guidelines, actually I have produced better water quality every time than what the spec calls for. I was told once Amines from virgin resin are not good for dialysis patients. I've never seen any literature on this before so I thought I'd just throw this out there and see what responses came back.

"That would be about 9 gpm in a 1" diameter pipe. Q = VA."

Kind of lost me on this volume equation. If I don't know the footage of the pipe loop, How would I be able to determine what the minimum flow should be?

I suppose I could go back to what we've said previously, calculate the maximum flowrate of a single faucet, multiply this by the number of faucets, add in any equipment that could possibly draw water as if the equipment were running with every faucet open (glasswash equipment ect) and add in the additional 5 GPM you mentioned. Do you think this would give me an accurate picture of what the flowrate in the loop should be?    

RE: Webtrol H10B8SS Pump Question

Convert gpm to cubic feet per sec. That is Q.  Eaample: 9 gpm = 0.02 cfs

Divide by area of pipe in square feet. That is A.  Area of 1" diameter pipe = 0.00545 square feet.

Q/A =  ft/sec. 0.02/0.00545 = 3.67 ft/sec

RE: Webtrol H10B8SS Pump Question

(OP)
"calculate the maximum flowrate of a single faucet, multiply this by the number of faucets, add in any equipment that could possibly draw water as if the equipment were running with every faucet open (glasswash equipment ect) and add in the additional 5 GPM you mentioned. Do you think this would give me an accurate picture of what the flowrate in the loop should be?"

Can you answer this question for me?

RE: Webtrol H10B8SS Pump Question

Yes that is correct.

RE: Webtrol H10B8SS Pump Question

(OP)
OK. Thanks so much. I'm going to be concentrating fully on this system next week. I'll have lots of information and data to share ,,, and of course more questions ,, Have a great weekend and thanks again!  

RE: Webtrol H10B8SS Pump Question

(OP)
I just installed a POU system with DI, UV and Ultrafilter. Looks like they want to shut down the loop system.

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