Quiet submersible pump

[f750]

Hi all, I would like some suggestion for a quiet pump to cool my 2.5 kw spindle. The one which was supplied when I brought the kit is the loudest thing when running the machine.

Cheers Tony

[Neale]

I use a cheap pump (Whale brand) sold for water supplies in caravans and boats. In theory, it's not rated for continuous operation but I run it on 5V instead of 12V (but with 12V available for filling the pipework when needed) and it runs for hours on end. Virtually silent running like that - I have to look for the odd bubble in the pipe to check that it's running. Never had any problems with overheating. I've been using it for years now. Others feel that more cooling is needed and go for PC water-cooling fans and radiators (which reduces pipe runs) or more powerful pumps but my experience has been that the cooling needed is often over-estimated. Maybe I just don't work my 2.2KW spindle hard enough...

[Voicecoil]

Yes, you don't seem to need a lot of cooling. I run my spindle (2KW) pretty hard at times and the water doesn't really ever get more than gently warm. My reservoir is a tallish aluminium pot though which will help by radiating heat rather better than a thick walled plastic container would.

[JAZZCNC]

Look for a pump used for solar heating, they come either 12 or 24v. They are designed for continuous use and very quiet.

[f750]

Thank you for suggestions I have ordered a solar pump. Next question is I just add normal car anti freeze to the water supply but found some debris in it when cleaning out the tank any thoughts.

Cheers Tony

[Muzzer]

Not sure why you'd add antifreeze to a spindle cooling system used in a workshop. What you probably need is some corrosion inhibiter - presumably the easiest source would be central heating additive from the likes of Screwfix or ebay? Hopefully there are people here who know the answer.

[magicniner]

Not sure why you'd add antifreeze to a spindle cooling system used in a workshop.

Perhaps because when used at the recommended concentration it includes the correct corrosion inhibitors plus chemicals which improve cooling as well as preventing freezing?

[f750]

That was my idea, my shed does get cold and I will use the red anti freeze for use with aluminium heads.

Cheers Tony

[Clive S]

I use a small dose of antifreeze to stop biological growth.

[JAZZCNC]

Perhaps because when used at the recommended concentration it includes the correct corrosion inhibitors plus chemicals which improve cooling as well as preventing freezing?

Exactly the reasons and it also stops bio growth.

[Kitwn]

One thing to be aware of is the effect the hose diameter has on flow rate. I'm using a 240V submersible pond pump and found that increasing the internal hose diameter from about 5mm to 8mm doubled the flow. Short narrow sections for connections to the spindle have little effect but over a 4-5m return trip it is significant.

[Neale]

Hey, Kit - is that a cooling system or a pressure washer? I hasten to add that I am joking...

But seriously, I'm inclined to think that cooling requirements are over-estimated, at least for the typical home-built machine. I would prefer to avoid 240V submersible anyway - mains and water don't mix and although clearly the pump is designed to run like this, why do it at all if not needed? My 12V low-flow pump running on 5V gives more a trickle than a flow, and that's through some metres of 4 or 5mm pipe. However, the combination of narrow pipe, low flow rate, and length mean that there is quite a lot of water cooling going on in the pipe, so the water going back round via a 10litre bucket is still fairly cool. Some few degrees above ambient, maybe 10deg if I've been working for a while, but I've never noticed it much higher than that.

[JAZZCNC]

But seriously, I'm inclined to think that cooling requirements are over-estimated, at least for the typical home-built machine. I would prefer to avoid 240V submersible anyway - mains and water don't mix and although clearly the pump is designed to run like this, why do it at all if not needed?

100% agree, the typical Water cooled spindle requires very little water to cool it. Every machine I build/sell uses a 24v submersible pump in a simple tank of water and for 99% of users this is more than enough, for users who are running jobs lasting multiple hours or days then we offer an upgrade with an aluminium tank, radiator and twin fans but it still uses the same water pump. Obviously, for people like kit who live in very hot countries, this will be slightly different but still, they don't need a massive flow of water.

Re 240v pump, then again 100% agree, in fact, our spindles come supplied with a 240Vac pump which we replace with a 24Vdc pump because I don't like water and mains voltages together. So have a nice box full of 240vac pumps if anyone wants a cheap pump....Lol

[AndyCD]

Hi Jazz, what are your thoughts on using one of those pumps for coolant? I have a manual mill in need of a coolant pump so might just take you up on one of your 240v spares!

[Colin Barron]

Suds pumps, that is a motor connected to a shaft and impeller a simple reliable arrangement you fit and forget. They are more expensive than cheap submersibles new but they are available second hand sometimes with a tank. No problem using 240v because they are away from fluids. They still make a similar model to that of 50 years ago.
https://www.mgeworldwide.com/aq4-pump-range

[Kitwn]

Neale,

Joke appreciated, but it's a very modest sized aquarium pump. I don't think any other voltage option was available locally when I set up this machine back in remote Western Australia and delivery times for mail-order were typically anything over 14 days so I used what I could get. Plus I spent most of my working life mixing up to 40,000V with water so perhaps I'm biased.

But think on this: The 240V brushless pump motor coils are fully encapsulated in plastic, the heavy duty 3-core mains cable is fixed in place and I don't often hold it in my hand. It doesn't get bent and twisted every day or trodden on and if the 240V does escape through the pump it will connect to the cooling circuit which is flowing through the spindle which is solidly bonded to mains earth and I have an RCD in my shed mains supply.
Now compare that installation to the cheap-shit 2-core mains lead on your wife's/daughter's/granddaughter's hairdryer.

Link to previous discussion on cooling pumps and the effect of pipe diameter on flow rate:
http://www.mycncuk.com/threads/12791-Plumbing-a-water-cooled-spindle

[f750]

Thank you all for your reply's, the new pump arrived today and I have fitted and run the pump. Nor really needed today as it is quite cool today but the pump felt cooler and a lot quieter.

Cheers Tony

[JAZZCNC]

Hi Jazz, what are your thoughts on using one of those pumps for coolant? I have a manual mill in need of a coolant pump so might just take you up on one of your 240v spares!

Don't know but you are welcome to try one, just cover postage and I'll send one over.

[Muzzer]

True, antifreeze contains small amounts of corrosion inhibitor but also loads of horrible messy glycol. The inhibitors are generally borates and silicates.

The cooling properties of water ethylene glycol (WEG) are actually slightly worse than neat water - it's primarily about preventing freezing damage. Best freezing protection is around the 2:1 ratio (glycol:water) which protects down to around -40C. Neat glycol itself actually freezes at only -13C. I can't work in a freezing workshop and have heating to protect my machines.

If you want to prevent corrosion and biological growth, you could add a tiny squirt of an inhibitor such as Fernox F1 to the fill (£9 from Toolstation etc). One bottle would last you many years and protect many machines.
https://fernox.com/product/protector-f1-500ml/