[Vagrant Storm]

I've seen in many posts that people give advice to have your hoses as short as possible. is there any reason for this? I know it will casue more stress on the pump and all, but say you have a Lang Li D5 pump?

I am just thinking of how i could put part of of my water cooling out side...like I mean out side the house. I live in Minnesota...if I put my resivor out side that is like a free water chiller six months out of the year. At the very least I'd like to move my radiator and reservior into my closet.

Think I'd run into any problems?

 

[atomicfission92]

long runs mean less pressure, and the pump only had 10ft of head.. So it will work. but you won't get the pressure you need

 

[reberto]

Um, yeah. you would need at least 2 maybe 3-4 pumps which would put too much stress on the tubing and radiator. Not a good idea

 

[bradleyl20]

Quote:

Originally Posted by Vagrant Storm I've seen in many posts that people give advice to have your hoses as short as possible. is there any reason for this? I know it will casue more stress on the pump and all, but say you have a Lang Li D5 pump? I am just thinking of how i could put part of of my water cooling out side...like I mean out side the house. I live in Minnesota...if I put my resivor out side that is like a free water chiller six months out of the year. At the very least I'd like to move my radiator and reservior into my closet. Think I'd run into any problems?

i would think that would be to much stress on the pump, i would think you'd need another pump out side your case to have good flow.

 

[atomicfission92]

Quote:

Originally Posted by reberto Um, yeah. you would need at least 2 maybe 3-4 pumps which would put too much stress on the tubing and radiator. Not a good idea

wouldn't really put any stress on the tubing and rad.... he just needs more then 1 to get it working right.

 

[Vagrant Storm]

Well, I don't need to go long distances here. to get into my closet the hoses would need to be about eight feet long and that's giving it a little leeway so I don't get the hose too short. To get it out side would need maybe another two feet. My wife has OK'ed me to drill holes to the out side from inside the closet. On the out side of the house I would put up an empty cable box when not in use and it would happen to be right next to the real cable box and the power meter so I probally won't even be affecting my property value. Maybe increasing it if an overclocker were to buy our house were we ever to sell LOL

So I am looking at arround 20 feet of hose here. I guess it would not be too much trouble to add another pump...if its far away I shouldn't need to have another D5...infact it would be away from my machine so I would really need to use a 120 volt pump which are ussually cheaper. Hmmm this could be fun.

 

[DigitrevX]

Correct me if im wrong, and I could be. But I though the head was how high a pump can push in a vertical tube simulating back pressure. If hes not pumping over 4ft vertically and doesn't have allot of restrictive parts in the loop it shouldn't be out of a D5's ability since its rating is a 10ft head.. That's my understanding of what a pumps head is?

Actually If the tube travels down as far as it does up doesn't it create a neutral back pressure. If that's true and since all WC systems are loops or circuits starting where they end there is always a neutral back pressure. So really the pumps head is only a measurement used to gauge how much back pressure a pump can overcome. Ultimately meaning it has nothing to do with up or down or left or right unless you have so much tube it in it self is causing back pressure. physically it sounds right but there's probably something I'm missing

 

[atomicfission92]

Quote:

Originally Posted by DigitrevX Correct me if im wrong, and I could be. But I though the head was how high a pump can push in a vertical tube simulating back pressure. If hes not pumping over 4ft vertically and doesn't have allot of restrictive parts in the loop it shouldn't be out of a D5's ability since its rating is 10ft.. That’s my understanding of what a pumps head is?

Yes that is it. but the thing is, with that much tubing, its a long distance, and and you lose pressure. unless its a totally closed loop with no res, where the pressure can stay the same.

 

[DontPassTheFence]

i could have sworn someone here HAD their rad outside and was loving the free chiller effect from winter... although it may have been a dream

 

[atomicfission92]

No that was someone here lol. For got where it was.. OH WAIT lol not here....

 

[fstfrddy]

Yeah, water seeks its own level, like my setup here, as long as I keep the res filled over the inlet it is really a zero head system, the ID of the system is the limiter.

 

[DigitrevX]

Quote:

Originally Posted by atomicfission92 Yes that is it. but the thing is, with that much tubing, its a long distance, and and you lose pressure. unless its a totally closed loop with no res, where the pressure can stay the same.

I think he would be ok because as long as the res is sealed like it should it should act like a expansion chamber and then continue on. The incoming liquid would force the exiting liquid out at equal force. There would be a small pressure drop just in the res similar to a expansion chamber on a ac unit but over all I think its worth a shot. I can’t prove it will work but if it was me and I had the parts I'd test it out and see how far it went.

If he did, we would all know for sure and this would be a quick answer to people with similar ideas.

 

[atomicfission92]

Quote:

Originally Posted by DigitrevX I think he would be ok because as long as the res is sealed like it should it should act like a expansion chamber and then continue on. The incoming liquid would force the exiting liquid out at equal force. There would be a small pressure drop just in the res similar to a expansion chamber on a ac unit but over all I think its worth a shot. I can’t prove it will work but if it was me and I had the parts I'd test it out and see how far it went. If he did, we would all know for sure and this would be a quick answer to people with similar ideas.

true, he know what, try it, if it doesn't work put another pump in the loop wth right try it. Experiment and learn for your self.

 

[born2killU]

dude feel free to use up to like 20 ft of tubing

read my faq about it

just casue the pump has 10 feet of head dosent mean it can only pump 10 feet

 

[DigitrevX]

Actually now that I think about it theres some one on here with a Mozart case that said he had over 15ft of tube with 2xgpu blocks, cpu block,3x 120mm rad, T line res, and 4 elbows and he did it with a D5. Not sure on how the flow was but I saw the pix he posted and was running. I'll try to dig it up.

edit: I could only find the old thread. In these pics he only has a 2x120mm rad and cpu, chipset blocks. But he does have 15ft of tube and one D5. And note in the pics that alot of the tubing is pretty vertical. http://www.overclock.net/water-cooli...hlight=Motzart

 

[Graystar]

The reason we keep hoses as short as possible is to reduce the head loss caused by water running through tubing.

Our PC water-cooling loops are considered closed systems. For a closed systems, the static head of the system is always 0 ft. Therefore, the vertical height of tubing doesn’t matter, but total length does. All the flow resistance against the pump is generated by friction alone.

Here are some head loss numbers:
The Friction Head of 4 ft of 1/2" tubing, at 2 GPM is 0.58 ft.
The Friction Head of 4 ft of 7/16" tubing, at 2 GPM is 1.141 ft.
The Friction Head of 4 ft of 3/8†tubing, at 2 GPM is 2.5 ft.
The Friction Head of 4 ft of 1/4†tubing, at 2 GPM is 20.58 ft.

In a typical water-cooling loop, the MCP-355/655 pumps usually operate between 1.5 and 2 GPM.

At 2 GPM, 4 ft of 3/8" tubing has the same head loss as over 17 ft of 1/2" tubing.

At 2 GPM, 3/8" tubing can rob nearly 24" of head from the pump. That represents a significant portion of head (20%) for a pump with 10ft of head. That’s why it’s important to use 1/2" tubing

The stress on a pump is caused by the drop in head across the pump. The longer the tubes, the greater the drop in head. When a pump is operating near zero flow, the lateral forces on the impeller are greatest. There are many stories of aquarium pumps with cracked impeller shafts. These pumps have high GPH ratings but could only develop a very low GPH rate in a water-cooling setup, hence their shafts are cracked by the high lateral loads. The specialty pumps we use today don’t have these problems because they are high-head and low-flow.

Adding a second or third pump to a highly restrictive loop will probably NOT reduce the stress on the first pump. You’ll just end up with three highly stressed pumps. The reason is that each pump has to work at nearly the same high-stress point as before to create greater flow. The better solution is to get a single that is suited to the pumping requirements. As much as possible, you want your pumps to operate within the range they were designed to operate in. That’s when the pump is most efficient and reliable.

Tubing and radiators CAN be stressed by pressure. Fortunately, the pumps we use don’t come anywhere near those pressure levels.

 

[ira-k]

Dead on the money, it's all about the friction and head loss...Very well said...

 

[pauldovi]

Do some research on Reynolds Number. As the length of the tube increases, so does viscosity. High levels of viscosity actually increase flow rate. I guess you have to find the balance between viscous flow benefit and the loss from friction.

Regardless, a D5 can easily pump water through a 20ft long loop.

 

[DigitrevX]

Quote:

Originally Posted by pauldovi Do some research on Reynolds Number. As the length of the tube increases, so does viscosity. High levels of viscosity actually increase flow rate. I guess you have to find the balance between viscous flow benefit and the loss from friction. Regardless, a D5 can easily pump water through a 20ft long loop.

how exactly does the length of the tube change the viscosity of liquid? Over time any liquids viscosity will break down, but if I had a 3 foot tube in the right hand and a 20ft coil in the left hows it going to change viscosity when I fire the system up?

 

[Graystar]

Quote:

Originally Posted by pauldovi Do some research on Reynolds Number. As the length of the tube increases, so does viscosity. High levels of viscosity actually increase flow rate. I guess you have to find the balance between viscous flow benefit and the loss from friction.

The Reynolds number is affected by Kinematic Viscosity, which is a ratio between Absolute Viscosity and Density. There is no accounting for tube length in the Reynolds number.

Neither does tube length affect viscosity. Viscosity changes with density and temperature.

Water is unique in that its hydrogen bonds create a sort of self-compression. From 1 PSI to 10,000 PSI, the change in the viscosity of water is insignificant.

I have yet to read about the effect you described, but it's clear that it could only occur at very high Reynolds numbers and with large changes in temperature and/or pressure...none of which occurs in the scenarios being discussed in this thread.