pipe size and pumps

[Bergovoy]

Hello,

Okay, not sure where I thought I saw this, but after I mentioned it to someone, they said I was not correct, (and I hate not being right all the time!!)

I know it is good to throttle back on the discharge side of a pump, but I am trying to combine that thought with some other issues, like capacity , flow rate and volume, (same thing??)

So, I have a Quiet on 6000, with aa one inch discharge. The discharge point up when the pump is sitting in it's normal resting position.

I installed a 1 inch union, then when from the union to a a one inch to a one and a half inch bushing to the one and a half inch pipe. This is still heading UP, (for about 6 inches)

I then installed a 90 to get the pipe to run horizontal (and parallel to the ground). At which point I installed a two 1-1/2" Tees for a manifold, (one to a chiller, the other to my ca reactor)

each Tee has a gate valve and union.

After the manifold, the pipe comes into my house, under the stand and then again, steps back down to a 1 inch pipe.

From that point it goes from one 1" pipe to a tee to two 1" pipes that come up into my tank through one inch bulkheads for my tank returns.

So, the question is, is the head alone considered a restriction towards thethrottling back that makes the pump more efficient?

Do I need to step down to a 3/4" to get tthat?

Is the 1-1/2" pipe helping or hurting?

Any thoughts?


Sorry for no pics, as I actually dont have this finished yet, (It is just piped tot he pump, and then to the 1-1/2" upwardly configuired pipe.

(that plus I dont have my camera today, it is my daughers and she is at her moms for the weekend.

Bill

[flat broke]

Bill,

The throttling back doesn't exactly make the pump more efficient in terms of gph/watt used. It will reduce the overall wattage draw, but depending on any particular pumps capacity to deal with head/frictional losses, it can also rapidly reduce the output of the pump. So it really boils down to your other needs that revolve around the pumps output.

So to answer one aspect of your question, plumb it how you need to in order to get your desired results.

But with regard to the other aspect as far as whether or not restrictions from line sizing and direction changes actually "throttle back" the pump in terms of energy used; I haven't measured it. Seeing as how you plumbed it with a union right at the pump, you have some flexibilty down the road as you can always revise your plumbing on the other side of the union and just buy a new union and use the half you need. If things aren't finalized, I'd just put a ball valve on the oulet of the pump. Then if you need to reduce flow later you always have the option, and if you don't the valve will just stay open. A couple bucks to not have to tinker with the plumbing again would seem worthwhile.

Good luck,
Chris

[Bergovoy]

Originally posted by flat broke
Bill,

. . .
So to answer one aspect of your question, plumb it how you need to in order to get your desired results.
. . .
Good luck,
Chris

Ummm, erego my question, what or how will I achieve those results.


i have re-written this messge four times, and each time I end up deleting it, as myquestion brings me into a endless loop, while I try to figure out what I am trying to say. It is like an egg and chicken issue,...

I will try again...

If a pumpmfg reccomnendsd throttling back on the discharge side of thier pump, is that taking into account the head loss and resistance in the piping itself? Or is thie reccomendat menant to be on top of that resistance???

ugggh, did that come out right???

[flat broke]

First question is "does the mfg actually recommend throttling back the pump for proper operation?" If the answer from the MFG is "yes" then install a valve, throttle it back and hope you have enough GPH left over to sustain your needs.

That being said, the only mfg that I know of mentioning throttling back the pump is dart/reeflow. There may be other mfgs that suggest the practice, I just haven't seen their pumps or read anything on their websites regarding the issue. In the instance of the dart, it's not like you "have to" or your pump will suffer, they just mention it, and probably intend it to be an added selling feature since some other mfgs don't mention it.

Perhaps the confusion is comming from the MFGs statement. Maybe they were merely trying to communicate that if you are going to throttle back the pump, do so on the outlet side. This is sound advice for any pump, as you don't want to choke the inlet and induce cavitation.

If it were me, I'd call the mfg for the pump listed and see what they have to say. If I had to guess (and this is pure speculation), you probably don't "have to" throttle back the pump. But if you need to, they'll recommend you do so on the outlet side. There is no way they could test for everyone's plumbing scenario, so I doubt they'd issue a blanket statement saying that you have to throttle back your pump by "X" percent before any head loss is calculated.

Now if you want to test how much wattage the head loss may be reducing energy consumption (and subsequently some linked amount of GPH); run the pump wide open in a bin while it's on a watt meter like a killawatt. The install it in your system where the plumbing will introduce the head pressure, and check the wattage draw again. That will give you some kind of indication as to what effect the head/friction losses are having on the pump. If every pump mfg used the same pump housing/impeller and held tight tollerance control on the motors and pump housings, you could actually establish performance curves that would correlate watts to gph. You could then merely watch the power consumption and know how much flow was reaching the end of the line/s.

Chris

[flat broke]

Thinking about this further, there is absolutely no reason other than cost and time that mfgs can't provide this info. They would have to specify a certain inlet pipe diameter, specific gravity and water temperature for their tests for the results to be repeatable and meaningfull to their customers, but beyond that it's pretty straight forward. They attach a gate valve then a flowmeter to the pump outlet. Then reduce and increase the flow with the gate valve measure the energy consumption of the pump in relation to the gph observed on the flowmeter.

This would actually be a pretty cool spec to have for some mfgs. They know their head performance, but many plumbing systems require pipe diameter changes and other variables that make it hard for the average hobbyist to compute the true gph discharged from their setup. If the mfgs had a correlation between watts and gph, you would only need to measure the power consumption to know the true output of their pump installed in your system. The industry/hobby has survived without it for some time, but it definitely falls into the "would be nice to have" area of product specs.

Chris

[Bergovoy]

Thanks for the info. You are right, I believe it a valuable piece of info that the mfg could include.

But before that, I think it equally or more important for testing to be standardized so that the results can be duplicated and compared one pump to another.

bill

[flat broke]

Unfortunately there are too many pump designs and variations of similar designs to be able to standardize. You could standardize the test in terms of the specific gravity and temp, but inlet diameter will change with pump size/type. When you look at the impeller from a mag vs say a dart, they are completely different and subsequently they will react to restriction differently. So you can't make any sweeping generalizations about gph/wattage performance.

Back on topic, did you get a hold of your pump mfg to verify whether or not you had to choke it down? I'd be curious to hear what they had to say so I can add it to all the other stuff rattling around in my brain.

Chris

[Bergovoy]

sorry, was busy today, but will find out tomorrow, and post the info.

It is the quiet one 6000, if you alrady have that in your catologue o stuff, let me know...
Bill

[flat broke]

Sorry Bill,

I don't have any info on Q1 pumps. I know their website doesn't mention anything about choking down or throttling back the pump, but beyond that, I couldn't tell you.

Good luck,
Chris