Suction Filter colapse

[R. skiffington]

Hi guys, this is not so much a question but a reminder. I had to change a 15hp Copeland today, when I removed the suction service valve I saw the strainer was full of particles from the drier core, the suction filter had colapsed completely. I'm not sure why the burn out drier had been fitted as the compressor was dated 1988, maybe there were concerns about acidity at some stage, but it's a reminder to us that burn out driers are designed to be temporary and must be removed after they've done there job! I suspect this was a huge contributing factor to one dead copeland!

[powell]

Hi guys, this is not so much a question but a reminder. I had to change a 15hp Copeland today, when I removed the suction service valve I saw the strainer was full of particles from the drier core, the suction filter had colapsed completely. I'm not sure why the burn out drier had been fitted as the compressor was dated 1988, maybe there were concerns about acidity at some stage, but it's a reminder to us that burn out driers are designed to be temporary and must be removed after they've done there job! I suspect this was a huge contributing factor to one dead copeland!

Good reminder skiffington. That's why we're told to check pressure drop.

[US Iceman]

I think you are being a bit hasty in saying this. If the suction drier was installed almost 20 years ago as part of the compressor replacement and the drier has never been changed until now this situation may have been caused by something else.

Drier cores are brittle and subject to abrasion or vibration. The long term effects of refrigerant flowing past the drier core or vibration from the compressor itself could have caused particles to shed from the drier over this time.

My practice was to first rub the drier cores very well with my hands to remove any loose particles before installing the cores in the drier shell. And I can't say that I ever left a drier core in for any length of time approaching 20 years.

I'm not surprised that you found some particles, but how much did you really find ?

[R. skiffington]

Ice man, I understand what you're saying but in this case, the drier (inline not with replaceable core) had completely coolapsed, mesh had let go and the felt and core (almost entire drier contents) ended up in the suction strainer. I still have the drier at the workshop actually, i'll try and get a photo on.

[chemi-cool]

Core driers [48 CI] in the suction line are dangerous and can "kill" the compressor.

In case of humidity in the system, the filter mash freezes and the compressor "sucks" the whole thing in, the are falling apart when temp is falling low inside them.

If you want to protect the compressor, install oil strainers on the suction line, they do the job fine and leave the driers on the liquid line to do the drying.

Thats from my experience for a "few weeks of work".

[US Iceman]

Every once in a while you hear and learn something new. I have not seen what you are describing and I certainly have no reason to doubt what Chemi says.

Never having experienced this type of event I might consider asking some questions:

Was the drier connection the same size as the suction line?

Have you tried to determine the refrigerant velocity through the drier core?

Just for starters....

I did not like the in-line driers that were brazed in place because it took so much effort to replace them. For that reason alone I always used the replaceable core units and to my knowledge never had an issue with them.

So as I said earlier...this is a new one for me!

[Magoo]

Your problem relates to a cheap ars## supplier, "do not look at flow rate of suction strainer, but the connection sizes ". The cheapest prime cost is the one used and installed. If any pressure drop occurs due to strainer doing its job, the thing turns inside out and resembles a dried date and can fry a compressor
Magoo

[US Iceman]

If any pressure drop occurs due to strainer doing its job, the thing turns inside out and resembles a dried date and can fry a compressor

You read my mind. I am very generous when it comes to sizing driers and this sometimes means the drier connections are larger than the suction or liquid line size.

[chemi-cool]

Ice man,

Can you explain to me, why on earth design engineers put a drier in the suction line?

I always throw them away, those with the cloth filter, get always partially blocked with returning oil or you find pieces blocking the oil filter, in other words, disaster.

[US Iceman]

Hi Chemi,

I'm speaking from my past experiences and observations only. I realize there may be some other factors I have not considered, so if I omit anything we can discuss it.

I prefer to define these by the separate functions they serve. Although we sometimes call these filter/driers or use the terms interchangeably to mean the same thing.

Filters only serve the purpose of cleaning solid particles out of the refrigerant stream. My personal preference if I were to use filters would be to place them upstream of the solenoid valves only. In ammonia strainers you can get the cloth filter bags for this. Strainers only catch the particles bigger than the mesh size. So the filter bags can catch the much smaller material. Compressor manufacturers also sometimes use them in the suction screens.

If there is that much junk in the system that would require filters then someone has done a horrible job of installing the system or working on it. And anyway, filters are only supposed to be temporary measures in my opinion. Leaving them in too long could present issues such as you are describing.

Driers on the other hand do just that. They are supposed to dry the refrigerant or keep it dry. We know what happens when the refrigerant gets some moisture in it, i.e, acid, burnouts, or TXV's freezing up.

Therefore what I started to do in an effort to keep the refrigerant as dry as possible was to install replaceable drier cores on both the suction and liquid lines. The strainers in these also provide some secondary cleaning, while the additional drier capacity helped to ensure the refrigerant was as dry as possible.

And, anytime I installed a drier shell I always used an over sized one. It might have been too much, but I always thought it was better to spend a little extra money when doing the job rather than doing it twice (or more times). My callbacks were virtually non-existent and the customers were happy.

Most original equipment manufacturers will not install a suction drier/filter because of the additional costs.

If I replaced a compressor, then a suction filter/drier was added as cheap insurance.

Just my thoughts. Please feel free to comment...

[chemi-cool]

If I replaced a compressor, then a suction filter/drier was added as cheap insurance.

Please explain how a drier on the suction line would do any good for the system?
I will except a filter even it can be a pain in the butt when it starts to get blocked, in liquid line' when a drier start to get blocked, it gets colder than the line or you can tell by the bubbles in the sight glass [thats if the sight glass is installed in the right place ]

Even in a new system, run OFN or Argon in the pipes while soldering and they stay shiny and clean so there is no need for any filter before the compressor.

Actually, I was asked to replace a 40 HP compressor and they insisted on installing a filter drier in the suction line, I asked for a reason and they didn't have any so I've refused to do the job.

To make a long story short, I haven't ever got a good reason for having one on the suction line, only problems.

[US Iceman]

Please explain how a drier on the suction line would do any good for the system?

It's just another location and opportunity to catch solids and more importantly to dry the refrigerant.

Even in a new system, run OFN or Argon in the pipes while soldering and they stay shiny and clean so there is no need for any filter before the compressor.

No argument at all on that point. A clean installation reduces a lot of the remedial work such as suction filters. And an adequate evacuation reduces the chances of moisture existing in the system.

[R. skiffington]

Going back now to the reason for the colapse of the drier, Ice Man, you mentioned vibration, one thing I noticed of the installation was the Vibration eliminator (Anaconda) on the suction line was mounted vertical to the crankshaft not horizontal, this really defeats the purpose of it, and looking at the position of the suction filter this vibration would certainly transfer into the drier, which may very well have helped with break down.
Now a question, a "suction line burn out drier" is used to help neutralise acid after a burn out, the driers you (ice man) mentioned that you were installing, were they used to neutralise acid or just for moisture removal?

[R. skiffington]

By the way the size of the filter matched that of the suction line.

[US Iceman]

Now a question, a "suction line burn out drier" is used to help neutralise acid after a burn out, the driers you (ice man) mentioned that you were installing, were they used to neutralise acid or just for moisture removal?

The ones I used were the HH cores from Sporlan. These are supposed to the acid core driers for burnouts. The way I looked at this was; if they are supposed to absorb acid from a burnout, why not use them all the time to reduce any potential acid that might form for any strange reason?

As I tried to mention earlier I tend to take very long view of how things work and the potential problems that can occur. My reasoning is to always get the maximum life out of equipment. That's why I fitted suction driers to systems I installed (new or replacements).

...you mentioned vibration, one thing I noticed of the installation was the Vibration eliminator (Anaconda) on the suction line was mounted vertical to the crankshaft not horizontal,...

That's not good. It appears someone took the easy way out during the installation. Drier cores are brittle. If you don't believe me just drop one and see what happens.

Vibration does funny things to a system and components. The long term vibration which could be caused by mechanical forces or flow induced forces could potentially cause the drier cores to shed material into the refrigerant.

[WINJA]

Ive seen this before , it eneded up with a burnt out compressor thru lack of suction cooling , after that we started using the suction port in the sump or head for the LP switch not at the service valve or winding cover

[naturalglow]

Hello, I am new to this forum and learned a lot from above discussion. Thanks to everyone.