Plumbing / pipe question

MfMan

Wnat to run a pipe from a connection across land to a new water trough some 200m distant. What size pipe is recommended? Is 3/4" heavy guage the right size to use or would 1/2" be sufficient? It's 3/4" to the connection....

reilig

MfMan wrote: »

Wnat to run a pipe from a connection across land to a new water trough some 200m distant. What size pipe is recommended? Is 3/4" heavy guage the right size to use or would 1/2" be sufficient? It's 3/4" to the connection....

Use 3/4 inch for at least 150m of the distance or all of it if you can. It would be permissable to put the last 50m in with 1/2 inch. Too much 1/2 inch pipe significantly reduces water pressure so if it was me I would spend the fow quid extra and pit it all in heavy guage 3/4 inch.

MfMan

Thanks, reilig. More concerned with doing job properly than skimping on price. On a related topic, anyone ever use Talbot Pushfit water fittings? Nearly impossible to get them to fit securely unless they're burred and pushed in properly. Don't really recommend them to be honest...

snowman707

MfMan wrote: »

Wnat to run a pipe from a connection across land to a new water trough some 200m distant. What size pipe is recommended? Is 3/4" heavy guage the right size to use or would 1/2" be sufficient? It's 3/4" to the connection....

Well I nearly got beat up in the local co op one day over this but if you want high pressure the smallest bore water pipe is the one to use


we use half inch here as we are pumping water up a hill ,

if you do not believe me place 2 pipes of different diameter straight up against a wall. block the lower end & pour exactly the same amount of water into each pipe, where will the water reach the higher level?

large diameter piping is fine on level or going with a fall but if you are going against gravity the least amount of water you are pushing will give you the highest head pressure at delivery point


common sence .. but loads of people fail to see it

reilig

snowman707 wrote: »

Well I nearly got beat up in the local co op one day over this but if you want high pressure the smallest bore water pipe is the one to use


we use half inch here as we are pumping water up a hill ,

if you do not believe me place 2 pipes of different diameter straight up against a wall. block the lower end & pour exactly the same amount of water into each pipe, where will the water reach the higher level?

large diameter piping is fine on level or going with a fall but if you are going against gravity the least amount of water you are pushing will give you the highest head pressure at delivery point


common sence .. but loads of people fail to see it

I would have to disagree. We had 3/4 inch piping bringing water about 600m to our house and found the pressure to be bad for years - had problems with pressure for showers and our slatted shed was connected from the same system and it only had a trickle. The pipe was running up a hill. Last year we replaced the 600m of 3/4 inch with 1 inch pipe and the difference was major. The pressure was so good that we actually had to put pressure reducing valves on the last 20 metres of 3/4 inch pipe that enters both the house and the shed. The guy that laid the pipe for us with a mole told us that he has seen it happen in several places where people have laid too small of pipe and ended up with low pressure. He stated that especially when the pipe has to run up a hill, it needs a force of water behind it in a large pipe to ensure constant pressure. He recommended only the last 50 metres of any length of piping to be in 1/2 inch to ensure constant pressure. In your experiment above, naturally the smaller pipe will fill up first, but the bigger pipe will hold more water and have more water pushing on the exit point and therefore have more pressure. The longer the length of 1/2 inch pipe, the less the pressure.

If this doesn't make sense, then look at the large 12 and 18 inch water mains that run from resevoirs and through towns. They have a tested pressure of 5 to 6 bar when operating properly, but if you test a 4 or a 6 inch branch which comes directly from these, you wil find the pressure to be around 3 bar (even if it is directly saddled off a 12 or 18 inch main). ie. the smaller pipe reduces the water pressure. Water for a house is approximately 1 bar - if your theory of the smaller the pipe, the greater the pressure were true, then the inch pipe leading to most houses in towns should have 10 to 12 bar of pressure (enough pressure to take the skin from your finger). It works the opposite way to what you say, the bigger pipes contain most of the pressure, then as you get closer to house connections, you make the pipe smaller to reduce the pressure.

Bitten & Hisses

The problem with small-bore pipes is friction: You lose a significant amount of pressure due to friction losses. Always go for the largest pipe size possible and you'll have a better water supply, your pump will be cutting in less and you'll use less electricity.

vincenzolorenzo

I'd have to agree with reilig on this one alright. If the pipe bore is too small then you'll lose far more pressure due to friction losses at the pipe wall. Larger bore means less pumping losses

bbam

snowman707 wrote: »

if you do not believe me place 2 pipes of different diameter straight up against a wall. block the lower end & pour exactly the same amount of water into each pipe, where will the water reach the higher level?

The lads are right... big difference in a few meters against a wall and 600m.
The larger pipe will also future-proof against adding extra drinkers at some stage... best be prepared.

Pete67

Sorry snowman, you're correct that the larger bore pipe will contain more water for a given length, however the static pressure or 'head' exerted by a colum of water is proportional to the height of the column. It does not matter whether the column is 1/2" wide or 10ft wide.

When pumping water, the pump has to overcome the static pressure due to the difference in height between the suction and discharge, plus the pressure drop due to friction once the water starts moving in the pipe. The frictional losses are much greater in a small bore pipe, so the pressure and flowrate at the discharge end will be lower due to the increased pressure drop along the length of the pipe.

Your mates in the co-op were right.

snowman707

i will not argue this point other than say I got water to a point on a hill using 90 psi from the source when an engineer with more letters after his name than in front told me it would not be possible & would require a booster pump in the farm yard.
since you all seem to know more about this than I do I will not waste your time but maybe some of you might be familar with a systen used in new zealand

I admit i do not have a high pressure but i have 2X300 gallon tanks at the drinking point so always have a reserve

we only have 1 pump (grundfoss) serving the farmyard, 2 dwelling houses & the farm in the summer

pressure might get a bit low at certain points when we are milking or the storage tank in the yard is filling but that isnt a problem

at peak in a dry year (wishful thinking) we would use anything 1000-1800 gallons a day

our last pump lasted over 12 years & must have pumped millons of gallons of water
BTW it takes 40 psi just to get water to the farm yard that will tell you how low our supply is, & yes we are using 1 inch piping for this just because we need a good volume of water in a hurry

OP very sorry for hijacking your thread but i have been trying to push H2O up hill since 1968 , maybe I should have used bigger piping lol , I don't think so! been there done that.

Pete67

Your solution works and more power to you, but so as not to mislead folks, let me put it this way. If you run two pipes side by side from the same pump to the top of your hill, one 1/2", and one 1", and try them one at a time, you will get more water out of the larger pipe every time.

job3

If you double the pipe diameter it increases water flow by a factor of 16. So in other words you will get 16 times more water by using a 1" pipe than if you were using a 1/2" pipe

powerfarmer

In an application like this it will always be better to use the largest practical diameter of pipe, I see snowman says for high pressure use 1/2" pipe but for an application like this a high flow rate is far more important ( and efficient) than pressure. I think pressure and flow are getting mixed up here high pressure does not mean high flow, pressure in fluid systems is caused by resistance to flow thats why snowman can get high pressure out of his 1/2" pipe because the small diameter is causing huge resistance to flow.
This in turn will be placing undue pressure back on the pump, causing it to consume more electricity than necessary and run for longer because of the poor flow through 1/2" pipe.
I dont know if anyone here saw the philmac demo at the ploughing for the last two years which really makes this clear in a practical way but they had the same lengths of 1/2", 3/4" and 1" pipe set up on a rig illustrating the poor flow, and increased pump running costs when using 1/2" pipe . Their guy commented that 1/2" pipe was only fit for hitting things with and wasnt even much good for that!

glenofthetown

Velocity v's Flow rate.



The first 50 meters there is a signifficant difference between the output of a 1" v's 3/4" pipe.

After this, friction loss and waters natural velocity kick in.



Pump water too fast and it gets crazy friction loss, pump water at the correct pressure in the correct size pipe and it achieves impressive results. Some times that means a 1/2" pipe and some times its larger.

Why are most of your water pipes at home 1/2"?



Dont be so sure that the snake oil men at exhibitions are there in your interest. Ask yourself what are they getting out of it??? at €€€ per fitting i reckon they have a vested interest!!!

Muckit

Some great debate and info being thrown out here. These are the kind of threads I like reading in boards. You can nearly hear the cogs turning in lads' heads!! Really enjoying it

The main thing I'm taking from it all is that pressure and flow rate are two separate things. Friction is the other important factor to consider.

On the fritction aspect, one thing I was surprised about was that nobody has mentioned fittings yet :rolleyes: ie the type and number of fittings will affect things.

reilig

Muckit wrote: »

On the fritction aspect, one thing I was surprised about was that nobody has mentioned fittings yet :rolleyes: ie the type and number of fittings will affect things.

Agreed.

And what about water meters? I don't know if they same types of meters are used across the country. But ours is located at the entry point of the water main onto the farm. The main is 3". there's a saddle on it which feeds a 1/2" pipe into the meter and the outlet from the meter is 1/2". It is then connected into a 1" pipe which runs approx 600m to the main dwelling house. This reduction to 1/2" just to facilitate the meter has to affect water pressure - even if it is just for about 3 meters.

pakalasa

Muckit wrote: »

.....The main thing I'm taking from it all is that pressure and flow rate are two separate things....

This is it in a nutshell. You have to consider these seperately.
On pressure
- For every 10Metres you pump uphill, you need an extra Bar (14.5 psi) just to reach that point, regardless of flow.

On friction
- When the water is not flowing in the pipe the friction loss is zero.
- When it's flowing, the larger the diameter, the lower the friction loss (pressure loss). The opposite with pipe length. The shorter the pipe, the smaller the pressure drop.

Here's a link showing the pressure loss;
Units are in US, ft and GPM.
http://www.engineeringtoolbox.com/pressure-loss-plastic-pipes-d_404.html

Note : I bar = 100,000 Pa (Pascal)

Joey the lips

For my money...There is no point using 3/4" as the mains it comes from is 1/2" Just run 1/2" all the way. If your worried about flow use a tank at the start with a sump pump in it to boost the pressure..... or indeed a sump pump half way along.


Most of the farming community drops this into ditches.... This can be good and bad. The good side to it is if there is a stream in the ditch it might prevent it freezing in winter, its quick and easy to lay and its easy to access.

The bad side to this is. rats can chew through it and the exposed parts may freeze.

As noted 1/2" hydrodare uses 3/4" fittings. Philmac are a great fitting for this job..

raindodger

have this year gone back to own well after being on council water.Well is on top of hill used 1 inch pipe for the main line stepping down to 3/4 and then 1/2 inch.I am having trouble with leaks at the ball cocks.
what is the best way to combat this is the 1/2 inch actually increasing the pressure on the seal rather than reducing as i thought .They are 1/2inch ballcocks with high pressure jets.

reilig

raindodger wrote: »

have this year gone back to own well after being on council water.Well is on top of hill used 1 inch pipe for the main line stepping down to 3/4 and then 1/2 inch.I am having trouble with leaks at the ball cocks.
what is the best way to combat this is the 1/2 inch actually increasing the pressure on the seal rather than reducing as i thought .They are 1/2inch ballcocks with high pressure jets.

Put a pressure reducing valve at the start of the 1/2" pipe. They will regulate the pressure and they can be adjusted up or down. Hills cause an increase in pressure and an increase in air (If you're having a problem with air, then an air valve might be useful too).

You'll get the pressure reducing valve in most hardwares for under €20.

raindodger

reilig wrote: »

Put a pressure reducing valve at the start of the 1/2" pipe. They will regulate the pressure and they can be adjusted up or down. Hills cause an increase in pressure and an increase in air (If you're having a problem with air, then an air valve might be useful too).

You'll get the pressure reducing valve in most hardwares for under €20.

thanks for the reply think i have seen the name in another forum is the bike put away now

just do it

reilig wrote: »

Agreed.

And what about water meters? I don't know if they same types of meters are used across the country. But ours is located at the entry point of the water main onto the farm. The main is 3". there's a saddle on it which feeds a 1/2" pipe into the meter and the outlet from the meter is 1/2". It is then connected into a 1" pipe which runs approx 600m to the main dwelling house. This reduction to 1/2" just to facilitate the meter has to affect water pressure - even if it is just for about 3 meters.

Yes same here. I've buried a new 1/2 inch to the shed from the mains connection last January to avoid it freezing. It's a 250m run. The pressure at the shed is crap. I was told not to bother with 3/4 or 1" as its 1/2" coming off the mains. I regret it now. It wasn't the cost of the pipe that put me off at the time, it was the advice I received!

If friction is a major factor, a few feet of 1/2 inch at the mains wouldn't have too much of an effect. 250m of 1/2 inch will!:(