What pipe is best for pumping sumps dry?

[tdobson]

I feel like this is a stupid question, and yet I feel like I could easily get this wrong, and only find out after hours of effort.

If I had a sump, with a long distance to travel to get to the downhill side of the syphon, what is the ideal type of pipe or hose to drain it?

Hose pipe, fire hose, gas pipe, water pipe - all are types of pipe. Obviously the wider the pipe, the faster the draining, but there must be other considerations? What has really *not* worked for people?

 

[JohnMCooper]

Any syphon causes flexible pipe to collapse so something like a firehose which rolls-up is no good.

 

[georgenorth]

For syphoning you need a suction hose, which tend to be relatively expensive. How are you planning on priming your syphon?

 

[Chris Curry]

I think we need more information to be helpful Tim. You mention pumping, but also a syphon. Which is it, or are you using a pump to prime a syphon? If so, what sort? The 'Earby' style pump works well in a lot of cave situations, and some folk have also had good results with marine bilge pumps. If it's feasible to run power there, some heavy duty submersible pumps work very well. You should also consider how far underground you are - bigger pipes will drain a sump faster but can be very cumbersome to get far underground. Layflat hoses are very convenient for transport, but only work when being actively pumped into and will collapse if used on the suction side of a pump. It also takes some power to keep them inflated which can reduce efficiency. If you could describe the sump and the plan in more detail I'm sure we'll be able to advise

 

[tdobson]

I think we need more information to be helpful Tim.

I appreciate knowing how little I know!

I almost acquired 30m of heavy duty gas piping this morning (for free) before I realised that getting it into my van was going to be a pain beyond what I could cope with, further than getting it into the cave.

If I'm honest, I haven't yet got a good sense of the sump to really have a firm plan, and clearly that's going to be crucial to forming a plan, but I think I'm talking about a relatively small amount of water in total, but quite a long distance of pipe to make a syphon work. I don't think running power there is possible, and I don't think air-burning pumps are ideal. There is a pitch within 50m of it though, so it might be possible to get a good head on a syphon.

Again, all details are relevant and interesting to getting something that works really well - apologies for the imprecise wordings, and lack of clarity - I'm learning here and gratefully taking on board everyone's advice. Thanks in advance!

 

[Ad W]

If you are planning a syphon, semi-ridged pipes like standard blue polyethylene water pipes are cheap enough good for syphoning as they won't easily collapse under suction. If you have enough people you can move them easily unrolled like a snake, but you need to watch out for what it does between people if there are formations about that could take damage. Definitely need someone on either end.

Smaller pipes are cheaper and significantly easier to move as more flexible, but flow rates are low, so only suitable for draining a sump that will recharge slowly. A valve on either end and t-piece and valve at the watershed makes it pretty easy to prime and start the syphon.

 

[Tritim230]

To drain the KPH pumps we used a submersible pump powered off a generator. We ran 80m of cable through the cave. No suction pipe as the pump sits in the sump. We used layflat hose on the outlet but even with a good pressure/flow it can be a pain to get the kinks out.

We also used a battery powered water transfer pump, which was slower. The disadvantage is the suction lift is not great <2m and will have trouble self priming, but outlet can lift 20m.

 

[alanw]

During our failed attempts to pump water out of Fat Finger, I bought some corrugated pipe like this

Black Flexible Pond Hose Corrugated Pipe Tube For Filter Pump Tubing Flexi Koi | eBay UK

Finest-Filters quality flexible pond hose. The hose is smooth inside, which allows for maximum flow rates from the pump, with minimal flow loss. The hose can easily be cut to size.

www.ebay.co.uk

for use with a bilge pump. It doesn't collapse under suction.

 

[Leclused]

It all depends on the configuration of the siphon, are you working from upstream or downstream? In the case of upstream and pumping the water through the siphon then we (SC Avalon) have a lot of experience. We have done that with several sumps in our project "Chantoir the Fagnoules".

exploration of Chantoir the Fagnoules

Especially part 4 and 5 are of interest for you

If more info is required ... shoot.

 

[Lankyman]

I'm not a smoker but I think something like a Meerschaum with a capacious bowl would last while you wait for the sump to break? You could also use the stem to point out interesting features of the cave to your companions.

 

[amw]

We have had success with rigged fire hose, you used to see it on reels in hospitals and schools. The stuff I have was from an old school demolition.

 

[Ian]

Just remember that the theoretical max syphon lift is on 10metres. Reality is usually less than that - especially if you have any mud

 

[JohnMCooper]

Any joins in the pipe must be completely air tight otherwise air gets in and breaks the syphon.

 

[tdobson]

Just remember that the theoretical max syphon lift is on 10metres. Reality is usually less than that - especially if you have any mud

Are you saying that the maximum a Syphon can usually do upwards is 10m, no matter how much down it has?

(Based on theory etc - I get the theory/reality distinction).

----

Really appreciating the hivemind of advice and experience. Absolutely inspiring. I'm now embarrassed not to be more prepared with all the specs of the project, but I have a fleet of possible solutions once I get my head a little better focused on the terrain.

Thanks for all the advice, and of course, more is always welcome.

 

[Ian]

The maximum uplift is related to air pressure. If you try and syphon higher all you do is generate a vacuum at the top of the pipe and the water won't flow. The outlet can be as low as you like, it's just the lift that's limited.
It's the same limit for suction pipes into a pump, which is why we can't situated the pump outside the cave with a very long suction hose.
After the pump it's just a question of how much pressure can your pump generate/your pipework handle.
A 10bar pump is generating 98.1 m head meaning it can pump up to 98m, ignoring friction losses in the pipes.

 

[Robbie Gee]

I feel like this is a stupid question, and yet I feel like I could easily get this wrong, and only find out after hours of effort.

If I had a sump, with a long distance to travel to get to the downhill side of the syphon, what is the ideal type of pipe or hose to drain it?

Hose pipe, fire hose, gas pipe, water pipe - all are types of pipe. Obviously the wider the pipe, the faster the draining, but there must be other considerations? What has really *not* worked for people?

Are you saying that the maximum a Syphon can usually do upwards is 10m, no matter how much down it has?

(Based on theory etc - I get the theory/reality distinction).

----

Really appreciating the hivemind of advice and experience. Absolutely inspiring. I'm now embarrassed not to be more prepared with all the specs of the project, but I have a fleet of possible solutions once I get my head a little better focused on the terrain.

Thanks for all the advice, and of course, more is always welcome.

Yes 10m is max lift for a syphon or any pump lift where the pump is at the opposite side to the fluid being pumped. It’s down to the atmospheric pressure acting on the water surface, this obviously can’t be changed. As previously mentioned this is theoretical lift, but in practice it will be less due to the viscosity of the liquid and frictional loss caused by the walls of any pipe used. Any lift over 10 meters, the only option is to pump directly from the water source.

 

[tdobson]

I'm so glad I asked thank you!!

 

[ChrisB]

10m (actually 9.81m) is the limit for pure water at sea level. Any mud that increases the density of the fluid, or any drop in air pressure with altitude, will reduce that. Friction and viscosity losses will depend on the velocity, if the flow is slow they will be low.

An off topic diversion: If the fluid is less dense than water it's possible to get over 10m; I'm aware of that being achieved for a pump by injecting air into the fluid at the intake so that the fluid column was partly bubbles, extending the lift to something like 12m. I suspect it's tricky to get right and the air at the top would stop a syphon working. It was done because a submersible pump would have been hard to maintain as the fluid was radioactive.

 

[Ad W]

An off topic diversion: If the fluid is less dense than water it's possible to get over 10m; I'm aware of that being achieved for a pump by injecting air into the fluid at the intake so that the fluid column was partly bubbles, extending the lift to something like 12m. I suspect it's tricky to get right and the air at the top would stop a syphon working.

Air-lift pumps use this principal of air injection alone. I have frequently used this to de-silt boreholes. This is the controlled injection of air into a riser-pipe inserted into a borehole to raise the water level in the riser pipe above ground level. There are limits to the amount of lift you can generate depending principally on sediment load (water density) and ratio of well above and below standing water level. Also more factors that affect potential pumping rates (water recharge rates, practical pump diameter etc).

Further off topic: Air-lift not to be confused with straight air injection/jetting, as this initially increases pressure in the well to push water out water at the surface, also pushing sediment back into the aquifer, where as air-lift with a separate riser only reduces pressure in the well during operation, drawing in sediment to be removed.

As per your example, I have used air-lift in conjunction with vacuum (vacuum tanker in that instance), to allow well development where neither technique would have worked alone.

 

[Sarataylor]

I feel like this is a stupid question, and yet I feel like I could easily get this wrong, and only find out after hours of effort.

If I had a sump, with a long distance to travel to get to the downhill side of the syphon, what is the ideal type of pipe or hose to drain it?

Hose pipe, fire hose, gas pipe, water pipe - all are types of pipe. Obviously the wider the pipe, the faster the draining, but there must be other considerations? What has really *not* worked for people?

Honestly, don’t bother with regular garden hose, its too slow and prone to collapsing. A lay-flat discharge hose or rigid pipe is ideal. If you’ve got distance, go wider diameter so you’re not waiting forever for it to drain.