Flushing cooling loop

[knighty]

I have a machine at work, heating plastic film to form into trays then seal lids on

Moulds etc. have a cooling loop, when i first got the machine i stripped it down and found most of the coolant paths in the aluminium moulds all furred up with (i think) aluminium oxide


Machine us in use now and the coolant isn't flowing at all, theres plenty of pressure from the pump and loads of flow if I bypass atraight back to the tank

If I get a bit of flow going, does anyone know something i can use to flush it through? Its a big job to strip it down, at least a couple of days... machine is running production 6 days a week so easier said than done.

Loop has copper and aluminium in them from what I can see

 

[Tom O]

CLR maybe?

 

[Jaeger_S2k]

Furring aluminium, usually caused by salt in the cooling solution.

Most corrosive liquids are too hard on aluminium because it's so solt, equal parts water and vinegar should be strong enough, but not for prolonged use.

 

[winchman]

We saved a fortune in professional chemical cleaning costs buy buying a machine for cleaning domestic central heating.
Loads of places hire them too

Proflush – Central heating power flushing solutions

proflush.co.uk

 

[knighty]

CLR maybe?

https://www.amazon.co.uk/CLR-Calcium-Remover-Enhanced-Formula/dp/B00009EFEX this stuff?

 

[knighty]

Furring aluminium, usually caused by salt in the cooling solution.

Most corrosive liquids are too hard on aluminium because it's so solt, equal parts water and vinegar should be strong enough, but not for prolonged use.

I was thinking vinegar, could pour some in then leave the cooler pump running overnight and flush the next day

not sure if I should warm it up a bit... or if that would be a bit too strong... will try cold first see how it goes

 

[knighty]

We saved a fortune in professional chemical cleaning costs buy buying a machine for cleaning domestic central heating.
Loads of places hire them too

Proflush – Central heating power flushing solutions

proflush.co.uk

I've got an (old crappy) power flush machine... but I think power/flow from the coolant pump should be plenty, I got an eye full off coolant when I tried to crack a pipe to check for pressure :-o

 

[voipio]

Copper and aluminium are not a good mix in a water-filled circuit, due to their widely different electrode potentials, and will greatly exacerbate any calcification issues. Is there any way of getting rid of the copper, and using aluminium pipework, or using plastic, like PEX, or alternatively silicone rubber, or reinforced plastic hose?

 

[knighty]

it's all a bit to intricate to change anything, almost all of the pipe is nylon, there's short bits of copper pipes going from the nylon hose to the aluminium moulds

pretty crappy design :-(

 

[hotponyshoes]

I'd have thought one of the car cooling flushes would work. Find one for a mixed materials system to remove the relevant deposits.

Then maybe blow out with air and refill with a proper solution of something like tig cooler fluid to stop it happening again.

 

[winchman]

We buy the flushing chemical from a chemical supplier one for copper based different one for stainless but from memory its not cheap but I am sure some one on here will know what to use, I also wondered about car rad cleaner.

 

[voipio]

it's all a bit to intricate to change anything, almost all of the pipe is nylon, there's short bits of copper pipes going from the nylon hose to the aluminium moulds

pretty crappy design :-(

If it's possible, putting a short section of plastic pipe between the copper and aluminium would help, by providing an electrically insulating gap between the dissimilar metals. By being joined together, as they are presently, the electrochemical cell formed by the aluminium and copper is being shorted out by the join, so causing a chemical reaction at the two electrodes (copper and aluminium). If both copper and aluminium parts are grounded, increasing the length of the grounding wires by quite a bit might also help, and stil be electrically safe.

 

[knighty]

If it's possible, putting a short section of plastic pipe between the copper and aluminium would help, by providing an electrically insulating gap between the dissimilar metals. By being joined together, as they are presently, the electrochemical cell formed by the aluminium and copper is being shorted out by the join, so causing a chemical reaction at the two electrodes (copper and aluminium). If both copper and aluminium parts are grounded, increasing the length of the grounding wires by quite a bit might also help, and stil be electrically safe.

it's nylon hose (like nylon airline) to copper at the edge of the mould, copper up to the aluminium where the water goes through a maze/path in the aluminium, then coper and back out to nylon

unfortunately there's naff all I can do to change it... probably could with decent down time but need the machine in production 6 days a week


((I keep saying nylon but it's probably not nylon, not that it makes any difference)

 

[knighty]

We buy the flushing chemical from a chemical supplier one for copper based different one for stainless but from memory its not cheap but I am sure some one on here will know what to use, I also wondered about car rad cleaner.

I thought about car radiator flush too.... but was worried that has to be hot to work?

 

[hotponyshoes]

I thought about car radiator flush too.... but was worried that has to be hot to work?

Usually deposits will break down at the same temperature they were formed so I would flush with clean water / a hose until no bits are coming out then add the flushing agent and run the system at operating temperature.
You might want to fit a temporary easy-to-access filter at the end of the loop while doing that. Then you could just keep an eye on the filter and let it run for 6 days.

If any of the copper/alloy joins are easy to access I'd pull a hose of and probe one to see if you have any galvanic corrosion as you might have to treat that differently.

 

[knighty]

Its blocked solid right now, no flow at all... tried reversing the flow and it made no difference.

It'll be the weekend before I can strip it down to have a look... its weird nothing has overheated... running film through the moulds cools them.... so think its balancing itself out right now

 

[hotponyshoes]

Its blocked solid right now, no flow at all... tried reversing the flow and it made no difference.

Have you got a multi-tool?
Weld a bit of round bar to an old blade and you can use it as an improvised ultrasonic hammer to get things moving.

 

[Seadog]

Its blocked solid right now, no flow at all... tried reversing the flow and it made no difference.

It'll be the weekend before I can strip it down to have a look... its weird nothing has overheated... running film through the moulds cools them.... so think its balancing itself out right now

If it's blocked solid it's unlikely that power flushing will clear it, especially if the corrosion is aluminium oxide.
Hydrochloric or sulphuric acids will disdolve it, but will also attack the base metal.
The same goes for sodium hydroxide.
Acetic or citric acids will disdolve it, but the reaction is slower.
How large (small) are the galleries, is there a chance that you can start to clear them mechanically?

 

[knighty]

my plan was pretty much to mess around and see if I can get some flow going, there's 4 moulds/cooling loops

I'll try and see if they're all blocked up or just one of them, see if I can get flow going trying just one at a time etc.

depending how well it goes I might have to start stripping them down and cleaning them individually... could probably do one a night 4 nights in a row

got my fingers crossed I could get the flow going then flush through with something

even if I have to strip them all down to clean I think I'd still be best flushing through with something after

I've got a filter to fit, I'll add that at the same time

when I filled it originally I put a decent dose of car antifreeze in it thinking that would prevent corrosion, maybe I used the wrong type, maybe it wasn't strong enough idk... I'll hunt out something better