Remove Suction Filter Elements??

[ChillTechnican]

Hey guys,
we do an annual service on some plant , change liquid driers , take oil samples and so on but also change the suction filters , the paper filter sort. When i asked why we did this i was told that we always had. Hmmmm i thought but why? Is it necessary to even have the element in there unless we have been doing some brazing on pipe work or something, i havent measured the pressure drop across filter , i quess if there is a couple of psi we may as well leave them in?
any thoughts appreciated

[old gas bottle]

i would be tempted to take them out as there more proned to blocking with oil residue,or put some flter cores in so they at least have a purpose.:)

[taz24]

Hey guys,
we do an annual service on some plant , change liquid driers , take oil samples and so on but also change the suction filters , the paper filter sort. When i asked why we did this i was told that we always had. Hmmmm i thought but why? Is it necessary to even have the element in there unless we have been doing some brazing on pipe work or something, i havent measured the pressure drop across filter , i quess if there is a couple of psi we may as well leave them in?
any thoughts appreciated


We used to leave them in for the first few months and then we took them out and left them out unless there was a problem with the system that required there use.

Cheers taz.

.

[Grizzly]

Hi CT.
Basically the unanswered question is how fine are these filters.
As Taz and OGB. have said it is normal to have these fitted into the suction line on a new install.
To collect any particles that travel through the system as far as the comp suction line.
On larger machines these are generally left in place for say 200hrs or a couple of days / weeks.
The amount of time depends on many system factors.
But the one common factor is that they are removed.
Once the system has ran long enough to guarantee the system is clean.
Then the only other time you may reasonably expect to see them would be after semi-hermetic motor burn out!
These are general factors and you may have a special but they are rare.

Take the advise above and remove them.
Grizzly

[US Iceman]

I'll take an opposing view.

Once the system was cleaned up/dry I might change them for a new set and leave them in. My logic: people tend to undersize driers or pull incomplete vacuums for dehydrating the system.

For air conditioning or medium temperature systems the pressure loss due to the cores is minor. For low temperature systems the increased pressure with the cores installed could increase run-time. The lower suction pressure resulting form the core pressure loss can decreases the vapor density (higher specific volume due to lower pressure) and reduce the compressor capacity.

[Grizzly]

I'll take an opposing view.

Once the system was cleaned up/dry I might change them for a new set and leave them in. My logic: people tend to undersize driers or pull incomplete vacuums for dehydrating the system.

For air conditioning or medium temperature systems the pressure loss due to the cores is minor. For low temperature systems the increased pressure with the cores installed could increase run-time. The lower suction pressure resulting form the core pressure loss can decreases the vapor density (higher specific volume due to lower pressure) and reduce the compressor capacity.

Good input Iceman!
I have no problem with what you suggest.
I mainly work on larger systems as you know, where suction line driers are rarer.

I personnaly would tend to question why a drier was there.( After all the size systems that I tend to work on don't tend to have them fitted as standard.)
And then based on the answer react accordingly.

In defence of the Engineers I know within the U.K.
Most worry whether they have pulled a deep enough Vac having opened up a system, rather than how quick it can be boxed back up!
Cowboys we have on both sides of the pond.
But the size of the equipment is relevant as well, is it not?
Anyway ChillTech.
It seems the choice is yours?
After all you know more about the equipment, your talking about than us!

Cheers Grizzly

[US Iceman]

My gut reaction is the driers work better in liquid rather than vapor service. Therefore I think the liquid line cores are a better suggestion (unless you are dealing with an burnout situation.

[ChillTechnican]

Thanks for replys. The filters we use are Sporlan RPE 100 and are an pleated felt filter not a solid core or anything, so pressure drop is probably not an issue but they do tend to have quite alot of oil in them when removed.
cheers all CT

[Grizzly]

Chill Technician.
My Initial reaction is they are more like "Commissioning Socks".
The filters that you have installed when a system is ran up for the first time.
Given that they saturate with oil.
I would try it without them fitted.
Whats anyone else think?
Grizzly

[mad fridgie]

I would choose after clean up (new or after problem) removing internals completely, the liquid line core and compressor suction mesh, should handle any remaining contaminents, if any

[US Iceman]

I agree with Grizzly about the socks/filters. They are intended for temporary duty. After some period of time has passed they should be removed on ***** systems.

I say ***** systems in general because of the oil return requirements. I have found these socks/filters tend to be OK on ammonia systems.

[moondawn]

Suction filters are primarily used to protect a new replacement hermetic compressor from residual acid from a previous burn out of a hermetic compressor. Residual acid must not be allowed to start attacking the new compressor winding insulation. Suction filters must be replaced as often as required in order to to absorb all of the residual acid. A built in Schraeder access port is usually located on the upstream side of the filter so that the pressure can be compared to the downstream pressure which can be measured at the SSV. The pressure drop across the suction filter can thereby be determined indicating when it must be replaced. Some filters even come equipped with both upstream and downstream access ports. Since system capacity is very sensitive to suction line pressure drop they must eventually be removed. Larger systems may have permanent suction filters which accept replaceable cores. When no longer needed for clean up of a burn out the cores are usually replaced with a felt filter that has minimal pressure drop. When space is restricted a Pancake type suction filter can be used.


i just been reading about these on a online course this is what it said
cheers
lee

[Peter_1]

We replace the paper/ ones after some weeks with a definitive stainless steel mesh (very fine holes) as a safety filter. (CCY48I)
Mostly from Carly http://www.carly-sa.com/carlysoft/documents/gb/CCY_DOCTEC_12_07_GB.pdf

[Peter_1]

Mount filter housing always so that the debris doesn't fall in the suction lines when removing the core.

[ChillTechnican]

Thank you all for replys, i plan to remove these felts after all the advice and opinions. cheers ct