Does anyone here have a good background with fluid dynamics and pumps? I'm trying to design a low flow mud shower that delivers a constant stream of thick clay like soft serve, around 0.75 to 1 gallon per minute from an overhead pipe. It's similar to the Cocoasoft Mud Shower videos, but with thicker mud and less flow. I am looking at using a 1/2 HP sewer pump that has 60 GPM and 15 feet of head with a 2 inch discharge.

The specific gravity of thick clay is 1.8 to 2, so the effective GPM of the pump for this application is 30, which feels too high. I plan to install the pump at the bottom of a mud pit with a 1 ft, dual mesh safety cage around the suction side to prevent delta P. I plan on putting a throttle valve so the flow can be adjusted from 0.75 GPM up to 3 GPM. How long would the piping need to be to deliver the right flow, and what size would the valve and pipe need to be to do the job? Is there a better sized pump on the market that will do the job? Many thanks to the community in advance. Youtube video of concept for reference:

https://youtu.be/1TSMyUn6dCo?si=OGLzNuxpa0Rheu7i

I wonder if you can heat it while its flowing thru the pipes?

Phil

I think the big unknown here is 'viscosity' - what counts as 'thick' for you? If you know, or can approximate that, there are likely equations and calculators available for pump size, flow reduction in pipe, etc. But without that, who knows?

If you are literally talking 'soft serve ice cream' - I think of that as 'stiff peaks that don't fall under gravity' - like you can have an ice cream cone 'stacked up' with soft serve. So it will be exceedingly hard to get that to even 'get drawn into' a pump.

A few references have soft serve viscosity anywhere from 100,000-500,000 cP. You're likely going to need some sort of wide open hopper and a screw-auger pump to move that ...which is pretty much what an ice cream machine is. Though maybe you could find an old salvage one?

Here is one table with some foods and viscosity ranges. Though any given food may have quite a range, so probably good to search more and get a good cross reference.
https://www.michael-smith-engineers.co.uk/mse/uploads/resources/useful-info/General-Info/Viscosities-of-Common-Liquids.pdf

For general ease of use, you'd need the mud to at least slump down under its own weight so it would have some chance to 'flow'. Even then, your pump is most likely based on a standard water viscosity of 1cP, but when you introduce thicker substances, you increase the possibility of cavitation at the pump inlet. Adding double screens would make that even more of an issue and even more so if you start putting restrictions in the system to lower the flow.

There are positive displacement pumps down in the 2-3 gallon range. So would be more naturally aligned with your intended flow rates without having to create a lot of restrictions in the system. The positive displacement would also help with pumping thick substances.


The heating / warming idea is neat. Would definitely make long adventures more tolerable. The one issue I've noted is that mud typically has terrible heat conductivity. An attempt to heat a small spot or patch, like with a cartridge heater or immersion heater, usually results in a really hot small patch.

But if you can spread out the heat, with a silicone heat mat - or keep the mud moving through a long section of heated pipe as mentioned - that might help. Use a lot of common sense - or some safety interlock. The bad thing would be turning on the heat, but not the pump. Then at some later time turning on the pump only to have a scalding hot blob of mud shoot out! So be careful!

The converse point in all this, if you're looking at 0.75-1 gpm, it might be easier to suspend some container and just let the mud drip out. Even 20-30 gallon container would be up to 40 minutes of 'shower'. So quite a long time there.

So in summary:

Viscosity is the key
You might have trouble throttling down a large pump.
Heat is neat but be careful!

Let us know how it turns out.

I once built one with some friends in the past. Instead of using an electric pump, we used a high-suction engine pump.
The route was: mud pool engine pump a boiler that directly heats water back to the mud pool.
We attached a remote control from an RC car to the engine pump, so we could freely adjust the power.
Thanks to this setup, the returning mud stayed warm enough for filming even in winter.

I think the pipe diameter was about 2 inches.

I've got something similar to what is seen in the video using a 5 gallon bucket and a spa pump. My pump can handle mud of the viscosity shown in the video however anything thicker than that and it lacks the ability to pull the mud into the tubing which might mean that the 2 ft of headspace in the plumbing system becomes too great. So, that by way of saying that the height the mud will need to be pulled up is a major factor in the size and type of pump needed.

I think that some sort of vacuum pump designed for use in pumping concrete would be the optimal solution. I've seen a number of semi-portable ones at quarries mounted on little two wheeled trailers they move around to pump mud in their settling ponds with. They seem to hand rather thick mud adequately.

Update on this post for people curious about a solution:

I went with a 1/2 horsepower motor and attached it to a 3D printed impeller, like this one here:

https://imgur.com/gallery/3d-printed-slip-casting-pump-QMdzSN9

It delivers 3-7 gpm depending on pumping distance / height and thickness of the clay. Which was problem #2. The super thick stuff does not play nice with the pump, so I had to water down and mix the top layer of clay to be liquid and runny.

To ensure the runny stuff makes it's way back to the pump, I used a thin and narrow plastic kitchen trash bin that stands 3 feet tall and cut an opening on the side that is 2 feet above the ground. This allows the runny slop to flow back into the bin and be re-pumped for an endless supply of mud. That bin is pressed into one corner of the pit, and the pump and motor are mounted on top of the bin - the plastic bin also acts as a safety barrier so no body parts end up getting sucked in. The 3/4 inch hose that connects to the pump has a valve and spigot at the end to control the flow.

Last of all, heat. I used radiant heating cable here - roof melt / roof de-icing cable that was 200 feet long / 1,000 watt heating output. The inside of the bin is covered with thermal wrap. The cable is coiled all the way around the inside of the insulated bin, so now we have 3,410 BTU/hour being delivered to mud flowing at 3-7 gpm, or 180-420 gph. Assuming 200 pounds of mud is flowing in the system and the mud starts at room temp, it would need to run around 1.5 hours to get to a nice and sensual 95+ F - a temperature probe that disconnects the power at a set level is recommended here so there's thermal safety. This also means the motor used to run the pump should be heavy duty and fan cooled - short run motors will burn out. This pump system should work on slime as well. The only difference would be having the gunge platform elevated and the pump at the bottom of a catch basin for endless sliming. Going to write a guide on this after some field testing.