Cleaning Hydraulic systems (valves and such)

[woodlandfarms]

So, pardon my noviceness... But I realize I know nothing about cleaning when I open up these valves and such. What are the solvent rules?

Here are some examples.

I use brake cleaning fluid to clean the outside of any oil carrying item. I spray the hoses, connectors, blah blah blah. I assume not damage can come from brake cleaning fluid.

I open my RPS valve, it has this bypass valve that looks to me to be made of aluminum or steel, has rubber o-rings, and as I remember some white hard plastic. I dig in it a bit, then hit it with Brake cleaning fluid and plop it back in.

I guess my question is, what solvents are OK, what aren't and I assume that there is no pre-lubing or extra sealant on the threads that are necessary. Maybe that last sentence about thread sealant / tape is a landmine. I understand that pressure threads like brake lines do not need sealant, but pipe threads, like the actual adapter that goes into my oil reservoir, does.

 

[J_J]

Matbe something like this.

Non-inflammable,
VOC-compliant contact cleaner Back Top

Krylon Products Group, the United States, offers Sprayon® Electro Wizard™ contact precision cleaner that instantly removes, dissolves and rinses away foreign contaminants from sensitive equipment and precision instruments. Available with a dielectric strength of 12,500 V, the VOC-compliant Electro Wizard evaporates instantly, eliminating trapping of airborne contaminants and allowing parts to be handled immediately. The non-inflammable cleaner, which is based on a new patent-pending formula, is safe on plastics and suits a wide range of applications, including printed circuits, relays and switches, meters and timing devices, X-ray equipment, radar, hydraulic and missile fuel systems, office machines, electronic games, computer systems and memory devices, satellite communication equipment, TV-video equipment, and cameras. Electro Wizard is an alternative to HCFC-141b, a Class II ozone-depleting substance that will be phased out by the Environmental Protection Agency by 2010

 

[Dominique01149]

From what I remember, there are 2 type of brake fluids.

Non Chlorinated Brake fluid is safer on plastic and o-rings.

The Chlorinated type can eat away at some plastics.

Aside from that, I'm hear to learn.

 

[SnowRidge]

The brake cleaner probably contains some type of alcohol. Check the MDS to find out. It will likely be on line. I'm not sure it would be a good idea to introduce alcohol into your charged hydraulic system, even though isopropyl alcohol is sometimes recommended for cleaning disassembled hydraulic components.

Some people recommend using WD-40 to flush QDs each time they are used. I don't know how appropriate this is, although I think it is surely better than leaving them dirty.

 

[Bob999]

Hydraulic fluids are petroleum based while brake fluid is not. It would seem to me (and this is just an opinion posted for the sake of discussion) that something like carburetor cleaner would be more appropriate.

 

[ponytug]

Hydraulic fluids are petroleum based while brake fluid is not. It would seem to me (and this is just an opinion posted for the sake of discussion) that something like carburetor cleaner would be more appropriate.

Personally, I think that brake cleaner is good for the outside of parts. There are two main types, one is water based and the others are hydrocarbon based, usually with some amount of CFC or CHCs. If you use the former, you may need to rinse of a residue. Brake cleaners have the tremendous advantage that it is designed to have no oily residue, but the water based versions may leave other materials behind. (You want your brakes to stick, not slide on a hydrocarbon film.) But keep it away from paint; most will soften/remove paint.

For cleaning the interior of parts, I am more careful, as there are a variety of solvents that attack rubber, e.g. soften, enlarge, degrade, and I am very careful to use nothing that leaves a residue. I use a pressurized solvent cleaner, similar to the electronics one J.J. mentioned, but only if the item is removed from the PT, and can be air blasted and dried before returning it to service. Electronics cleaners tend to be good at not destroying fiberglass and aren't conductive, but some recipes are death on paint and rubber, since neither is common on a circuit board.

It is not uncommon for me to wash with a spot treatment of citrus degreaser or Dawn, then a rinse, followed by detergent & water, followed by another rinse, followed by air, followed by brake cleaner, followed by air. Sometimes the best way to remove something is to get it dissolved in something that you can remove with another cleaner.

WD40 is a penetrating fluid designed to as a Water Displacer, recipe #40, aka WD40. It soaks into rubber in some not so great ways. I tend to avoid it except for its' prime use. (Cleaning QDs would fall into that category for me, as they are mostly metal, and the alternative, letting dirt in the system is definitely "Not Good".)

I think the key is ensuring that you select either a zero residue product, or you use one where the residue is something that you can either tolerate, e.g. WD40, or a material that you can clean off.

Before opening a hydraulic system, I try really hard to wash and blow off all dirt, and all dirt in the general vicinity. with a 10-25 micron dirt limit, I am really, really, conscious of how dirty my repair environment is normally.

You do have a filter on your air supply, right? Just don't use a FRL unit to clean your hydraulic cooler fins...

All the best,

Peter

 

[Gravy]

Many brake cleaners will ruin seals and o-rings. Read the label to be sure.

 

[J_J]

Danfoss said to use an oil based cleaning solvent.

 

[Wayne County Hose]

Most of your o-rings are nitrile, as are the inner liners of hydraulic hoses. The ingredients in most brakleen type products attack nitrile. However, in my experience, if you spray it on and wipe it off quick, it doesn't have time to do any real noticable damage. Always coat the o-rings with oil before reassembly otherwise you risk tearing them up.

 

[woodlandfarms]

Most of your o-rings are nitrile, as are the inner liners of hydraulic hoses. The ingredients in most brakleen type products attack nitrile. However, in my experience, if you spray it on and wipe it off quick, it doesn't have time to do any real noticable damage. Always coat the o-rings with oil before reassembly otherwise you risk tearing them up.

So, Wayne, what do you use as a pro to tear down and rebuild systems (in terms of cleaning).