System flushing

[Mickvee]

Is there any engineers out there who has any experience or feels the need to us flushing agents on compressor burn out AC systems. Myself I have never done it, but is it really needed with the use of burn out filters.

[Latte]

Never know anyone to flush systems out although the equipment is easilly available.

Have used bi-directional driers many times on a/c on on refrig systems used liquid and suction drier and never had a problem.

Whilst on the subject, how does a bi-directional work, surely is you reverse the flow anything caught in the drier will be pushed out again.

Regards

Fatboy

[frank]

Hi Mick

We had a go at flushing a few months ago - Disaster - well we wait and see. :)

The job called for 2 x R22 units to be removed and replaced with R407C units. The pipework lengths were approx 50m so we thought, hey, save a few quid and flush, it's all above a suspended ceiling, a nightmare to strip out and a bigger nightmare to replace.

Stripped out the condensing units, stripped out the indoor cassettes, looped the indoor pipework, pushed in 5ltrs of flushing agent, connected OFN to circulate and then to recover. Bang. Only 3.5ltrs comes back into the bottle. The last 1.5ltr took ages to return as it just coats the inside of the pipework. I still think to this day that we did not get it all out. How can we tell?

Only time will ???

Really dreading the call in 11.5 months time - "out system is not working" :(

[Sir Josiah Sodd]

.

Whilst on the subject, how does a bi-directional work, surely is you reverse the flow anything caught in the drier will be pushed out again.

Regards

Fatboy
.


The bi-flow drier has a twin chamber and an arrangement of check valves so that the part of the drier not in use is by-passed.

A suction bi-flow drier only works as a filter in one direction and bypasses in the other as the suction acts as a discharge pipe in heating. A liquid drier filters in both directions with the unused part by-passed.

I had some diagrams tucked away somewhere…….



.

[chillin out]

I wonder if the inside spins round in the direction of the flow? :D

[botrous]

I flashed systems twice , for an identical unit , compressor burn out , and i suspected that some of the vernish of the compressors motor coil is in the system so i flashed the system and everything went well . . . I think it's a good idea when u suspect inpurities in the system

[Mickvee]

Hi Frank
Which flushing agent did you use? I have read of an agent called CF-20 but I cannot find much info about it. It is enviromentally safe, bio-degradable and can be vented to atmosphere. Has anyone out there ever used it?
Hi Mick

We had a go at flushing a few months ago - Disaster - well we wait and see. :)

The job called for 2 x R22 units to be removed and replaced with R407C units. The pipework lengths were approx 50m so we thought, hey, save a few quid and flush, it's all above a suspended ceiling, a nightmare to strip out and a bigger nightmare to replace.

Stripped out the condensing units, stripped out the indoor cassettes, looped the indoor pipework, pushed in 5ltrs of flushing agent, connected OFN to circulate and then to recover. Bang. Only 3.5ltrs comes back into the bottle. The last 1.5ltr took ages to return as it just coats the inside of the pipework. I still think to this day that we did not get it all out. How can we tell?

Only time will ???

Really dreading the call in 11.5 months time - "out system is not working" :(

[frank]

Hi Mick

I can't remember off hand the name of it but I will investigate and let you know :)

[2002kahuna]

When I first started doing this work the fellow I learned a lot form said to removed three feet from the suction line, replace the liquid line dryer, and replace the unit. According to him all the varnish and garbage from a compressor burn out accumulates in the first three feet of the suction line. He had been in the business for years.
I have used this method for twenty years and have never had a problem.

[Mickvee]

On AC systems with suction line accumlator, would this have to be replaced as well as the compressor on a burn-out ?

[botrous]

I've read this article about flashing the systems after compressor burn out and would like to share it with you guys and see what you think . . .

Dirt Devil

The practice of solvent flushing a Refrigeration or Air Conditioning system has never been an acceptable method for treating a compressor burnout. Even in the days when R-11 was plentiful at about a buck a pound; flushing with R-11 caused serious problems.

I once sent out a new Service Tech to purge, evacuate and prepare a rebuilt compressor for start up on an old 25 ton system. This Tech was a rising star in the company having graduated with high honors from a top Refrigeration Trade School. He loaded the system up with about 10-15 lbs of R-11 backed with a bottle of nitrogen. After a few hours, the Tech called into the office complaining that his vacuum pump was not pulling down very well. I went out to the job site to assist. I arrived with the notion of a leak somewhere in the new connections. After the Tech explained to me everything he had done, I knew we were in for a long night.

Loading the system with R-11 turned into a nightmare. The solvent became trapped at low points in the piping. Every bend, nook and cavity in the piping contain small amounts of liquid R-11. Attempts to blow out the R-11 with nitrogen did not work. We connected two vacuum pumps and let'em run overnight. The residual R-11 was difficult, if not impossible, to completely boil off.

Recently, a few Chemical distributors have introduced [new] flushing solvents to internally clean piping. I bracket the word "new" here to bare out a half truth. These solvents have actually been around since the last supper. The only thing "new" is the intended application, "your next compressor burnout".

The solvent bottles are painted with extravagant claims many of which categorically are untrue.

………….leaves no residue

Physically, these solvents have a substantially higher boiling point than R-11, and we could not get the solvent to phase into a gaseous state under high vacuum. Another negative is the oily texture of the solvent which imparted a thin film coating to all our glassware. It was clear-cut that large quantities of solvent would remain in any system so treated.

.…. ……Neutralizes acid

We investigated the general chemistry of the solvents. The solvents all had an acid number. Not a good sign, but not an unexpected result, since solvents which best dissolve oil must have an acidic ionic character.

……….non hydroscopic

A readily identified compound in the solvent base uncovered Acetone. You can’t find too many compounds more hydroscopic than Acetone. Water adsorption from short term exposure to the atmosphere is faster and greater with Acetone than with a POE or PAG lubricant.

……….will not contaminate oil

Now here is a direct contradiction to the top claim. If the product does not leave a residue why would there be concern for oil contamination. It is because the solvents are polar and will integrate completely with oil. The viscosity of Oil summarily degrades with solvent contamination.

I will state for the record some nice attributes of these solvents. They all performed exceptionally well for cleaning and degreasing. No boner to pick here on effectiveness, the solvents removed grease, dirt and dyes. We also observed good softening action on my barbecue grill. By all measures of solvency testing, we award the high hard one, a letter grade of "A".

When marketing a cleaning product be aware of advertisements which strike a psychological chord. The use of catch phrases which stress the dangers of unclean conditions are most effective.

"I don’t want you liven in no roaches."

Certainly the marketers of the flushing agents don’t want you liven with the carbon, sludge, acids and other evil demons left over from a burned out compressor.

We live in a dirty world and we need:

"a white tornado that’s stronger than dirt with a clean that sparkles and a shine that lasts"

The psychic virtues of sanitary stimuli are powerful selling points and we are all culpable to some degree. In the case of solvent flushing a system, the science of proper Refrigeration practice is violated, but talk'in dirty can persuade the unconscious mind.

Assume the missionary position and brace yourself for the ride. The best way to flush a system is the old fashion way. Install a suction and liquid line drier, pull a deep vacuum, fully charge the machine and energize. All the carbon, sludge, acid and other evils will be power flushed into the filter cores. Let all the natural juices flow with each compressor stroke. The Refrigeration System is a continuous self cleaning apparatus. Engaging in lengthy foreplay with a solvent flush consumes useless time, expense and energy.

As I stated earlier these solvents are excellent cleaner/degreasers. My only objection is with their proposed application. I believe there is a place in our industry for top quality solvents as long as they are used on the outside of the cooling equipment.

Remember, R-11 was the most effective cleaning compound ever made. Industries world wide relied on R-11 for cleaning and degreasing in just about every manufacturing sector. R-11 was the "perfect solvent", electrically nonconductive, non flammable, non combustible, quick evaporating leaving no residue. To date, no one has been able to duplicate or find an equal replacement solvent for R-11. The company that does will get layed with billions.

source : http://www.refrigtech.com/talk.html

regards