Acid for raw water system flush

[DDW]

I would like to flush the raw water system on the sailboat. Rydlime seems to be hydrochloric acid, Barnacle Buster is phosphoric according to their MDS. Both seem to be ordinary acid repackaged for marine use at a good markup.

Is there a difference in speed or damage to metals between the two? Do they contain anything other than acid?

Premixed Barnacle Buster is <10% and $35/ gallon at the discount shops. I can buy phosphoric acid at Home Depot for $18/gallon, MDS says 35-45%, so 4 gallons mixed to 10% or approximately 10% of the cost while being more easily available.

Anybody used this? I've searched, there are side references in other threads but not addressed head on.

 

[DavidM]

Barnacle Buster and Rydlime may have detergents that help remove marine organisms bound up in the scale. But in so far as scale removal itself, 10% (by weight) HCl (muriatic acid) works best, phosphoric acid second best.

David

 

[DDW]

Interesting test from Practical Sailor here. Interesting in part because it attempts to quantify the damage to steel and aluminum by the various preparations and showing that citric and oxalic may be far worse than hydrochloric or phosphoric.

Also found a reply from the BB founder.

Also a more scholarly paper, suggesting that they all work somewhat similarly, with HCL a little better than phosphoric.

None of which is particularly dissuasive of using phosphoric from HD.

 

[Cigatoo]

Following

 

[TJM]

I used BB a few years ago on my air conditioning units heat exchangers.
I set up a 5 gallon pail with an old bilge pump and let it cycle for over an hour.
It worked awesome and removed everything I had wanted.
Dont be cheap on a proven product.

 

[kapnd]

Acid cleaning of raw water systems is destructive, and IMO, not something that should be done unless it becomes absolutely necessary.
A good visual inspection should precede an acid flush to determine if decreased raw water flow is caused by a worn impeller, crushed hose, debris in the system, or whatever.
Most recirculating flushes fail to include the mixing elbow, which could be the culprit all along!
Proactive maintenance (Regular fresh water flushing) can greatly reduce the need to acid flush.

 

[Northern Spy]

It is not destructive if you know what you are doing. There is a whole industry around scale removal from heat exchangers using (mainly) acid as a cleaner. If one knows the materials of the system (and more importantly, the scale), one can get an acid cleaner to work very well without any damage.

In the case of our boats, the metallurgy and materials are all pretty common, and the scale is similar too. These companies would not exist if they continuously damaged people's boats.

Making your own concoctions is iffy, unless you have a good grip on chemistry. Just because rydlyme is HCL and Barnacle Buster is H3PO4 on the SDS, doesn't mean there aren't other buffers and surfactants in there. Concentration isn't discussed either.

Most acid cleaning solutions are highly proprietary. I've had to sign NDAs just to attend meetings to discuss the cleaning process, with a solution with a very generic SDS with lots of overlapping percentages.

So yeah, if you know what you are doing, you could probably get away with cleaning with a homemade acid cleaner.

But the value added of Rydlyme and others is that it is already done for you, with a margin of personal and equipment safety.

 

[Simi 60]

I used BB a few years ago on my air conditioning units heat exchangers.
I set up a 5 gallon pail with an old bilge pump and let it cycle for over an hour.
It worked awesome and removed everything I had wanted.
Dont be cheap on a proven product.

Like watered down phosphoric acid ?

 

[Simi 60]

!
Proactive maintenance (Regular fresh water flushing) can greatly reduce the need to acid flush.

Sounds a bit unrealistic.
A bit like flushing the salt out of an outboard that is used daily in salt water.

 

[Simi 60]

Making your own concoctions is iffy, unless you have a good grip on chemistry. Just because rydlyme is HCL and Barnacle Buster is H3PO4 on the SDS, doesn't mean there aren't other buffers and surfactants in there. Concentration isn't discussed either.

.

It certainly was on the msds I downloaded.

 

[DavidM]

I am a retired chemical engineer and early in my career I worked in the industrial chemical cleaning industry cleaning boilers, heat exchangers and other process equipment fouled with water scale.

We normally used hydrochloric acid (HCl, muriatic acid) blended to 10% by weight concentration with about 0.1% inhibitor. The inhibitor reduces corrosion rates about 100 fold in steel systems. We sometimes used phosphoric acid on 316 SS systems that could be affected by well known chloride stress cracking corrosion and it worked fine, just slower. Both were heated to about 140 F to use.

As a boater I used Barnacle Buster once on my raw water system, after first mechanically cleaning and pressure testing the after cooler and making sure there were no tubes blocked by scale or impeller bits. It worked very well. I circulated the solution through the R/W system at about 120F (used the engine to heat it up) for several hours.

While circulating the solution I took a sample and applied the crude but effective "nail test" to test for inhibitor effectiveness. You take a shiny common nail, no galvanizing or any coating and put it in a sample of solution. If the inhibitor is working right you will see no tiny bubbles coming off of the nail, an indication of reaction of the acid with the metal. If no bubbles then the inhibitor was working. If you see bubbles then that indicates the absence of an inhibitor or the wrong inhibitor.

So I tried the nail test and I got bubbles, ie no inhibitor. I found that shocking and an indication of malpractice and fraud on the part of BB. Don't know about Rydlime. An inhibitor would add pennies to the cost of a gallon of BB.

But at the end of the day, the corrosion resistant materials in your R/W system: bronze exchanger shells, cupronickle tubes, cast iron, minimizes corrosion effects. I sure wouldn't do it very often though.

And if you know anyone in the chemical cleaning industry, ask them for a cup full of HCL inhibitor, we used to use Rodine 213. It will last you forever.

David

 

[DDW]

I'm leaning towards Barnacle Buster as it appears to be kinder to aluminum. The PS test did compare Rydlime with HCL at about the same concentrations, and in both steel and aluminum there was s signficant difference. I'm not sure what inhibitor I would use in phosphoric for both steel and aluminum (I believe there are bits of both in my raw system). But if I need to track down and mix a few things then the high price of the pre-made solutions begins to make more sense.

I'd agree not to do it daily. In the trawler I fresh water flush after the boat is used. I'm adding a system to do that on the sailboat, but want to clean it first. I haven't looked inside the engine, but the refrigerator heat exchanger had significant scaling, so probably the engine too.

 

[DavidM]

There should be no aluminum in the raw water system. All acids attack aluminum. Do not use any acid cleaner on an aluminum other than cosmetically brightening it on the outside. In that case we used phosphoric acid.

David