Webtrol H10B8SS Pump Question 1

[PurewaterGuy]

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.

 

[bimr]

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.

 

[jonr12]

All you need is an 8 GPM Dole valve.

 

[PurewaterGuy]

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.

 

[bimr]

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

http://www.asahi-america.com/.../O&M Constant flow valve.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.

 

[PurewaterGuy]

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.

 

[bimr]

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

 

[PurewaterGuy]

"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?

 

[bimr]

Correct. The flow should be approximately 5 gpm.

 

[PurewaterGuy]

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.

 

[bimr]

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.

 

[PurewaterGuy]

Great idea and thanks ,,,

 

[PurewaterGuy]

Pretreatment side

 

[PurewaterGuy]

Post treatment side --- Discharge side of pumps

 

[bimr]

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.

 

[PurewaterGuy]

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?

 

[PurewaterGuy]

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?

 

[PurewaterGuy]

This picture goes with the hand drawing, this is tough on line, but it's all I have. I really do apologize. I do appreciate the input. Just trying to get the job right.

 

[bimr]

Your diagrams are difficult to follow.

Here is a flow diagram of a typical ultrapure water system. As you can see, a backpressure control valve controls pressure/flow in the loop. The valve is shown above the storage tank.

 

[PurewaterGuy]

I wish I could post pictures inside this forum box. It would make things a whole heck of a lot easier when trying to ask a question or explain something.