Filtration 101

[CraigAClark]

If you get a compressor with a filtration system or add filtration to a compressor that was acquired with out it, there are some things you should know. Every compressor manufacturer that provides filtration with their machine, advertises a capacity for that filtration. There is also some FINE print that says something like "at standard inlet conditions". Standard Inlet Conditions refer to the gas temperature when it leaves the final separator. Generally, this inlet temperature for an air cooled, reciprocating compressor is 15 F above the ambient operating temperature. If a manufacturer uses an inlet temperature of 68 F when referring to the processing capacity of their filtration, this means that the ambient operating temperature would have to be 53 F to get the full rated capacity. Operating in temperatures above the "standard" reduces the processing capacity. Why, you may ask? The answer is that higher temperature air holds more moisture. The descecant chemical (usually a molecular seive) controls the life of the filtration (whether you use cartridges or repack). The greater the moisture content of the gas entering the filter, the faster the descecant is used up, resulting in shorter filter life.

I'll have to save more for later.

Craig

 

[PCBCaptChris]

Keep it coming. That is good stuff.

 

[pescador775]

The answer is that higher temperature air holds more moisture.

Craig, the phenomenon is not a function of the ability of air to hold water, it is related to the inability of 13X dessicant to entrap water at high temps. Dessicant does not absorb water. Vaporshell 13X is an adsorber which means that the water is physically trapped (sieved) while in a gaseous state as opposed to being "soaked up", eg moving into and mingling with and being held in the matrix by atomic forces or polarity. The dessicant material (zeolite) is characterised by many small pores or entrapments on the order of 10 angstroms size. These pores are so small that individual water molecules can be trapped and held permanently. However, this ability varies depending on the energy of the molecules. "High temperature" simply means that the molecules are moving at higher speed. This has an effect on the ability of dessicant to trap and subsequently hold the molecules. At high temp (high energy and speed) the molecules may richochet out of the dessicant and reenter the air stream, or burst free as temp rises.

 

[CraigAClark]

Craig, the phenomenon is not a function of the ability of air to hold water, it is related to the inability of 13X dessicant to entrap water at high temps. Dessicant does not absorb water. Vaporshell 13X is an adsorber which means that the water is physically trapped (sieved) while in a gaseous state as opposed to being "soaked up", eg moving into and mingling with and being held in the matrix by atomic forces or polarity. The dessicant material (zeolite) is characterised by many small pores or entrapments on the order of 10 angstroms size. These pores are so small that individual water molecules can be trapped and held permanently. However, this ability varies depending on the energy of the molecules. "High temperature" simply means that the molecules are moving at higher speed. This has an effect on the ability of dessicant to trap and subsequently hold the molecules. At high temp (high energy and speed) the molecules may richochet out of the dessicant and reenter the air stream, or burst free as temp rises.

I don't think so. Been building systems fo 20 years. If what you are saying was true, RH sensors wouldn't work. Think again! Pretty words but don't mean squat. Don't believe me, Ask Mike Casey at Lawrence Factor.

Craig

Craig

 

[DA Aquamaster]

Think again! Pretty words but don't mean squat. Don't believe me, Ask Mike Casey at Lawrence Factor.

Pretty words do mean a lot to the people who understand them. These also tend to be the same people who understand something due to the underlying theories or operational principles rather than relying on a less rigourous and sometimes logically flawed argument where something must be true because someone important said it was true. Or in other words...name dropping and authoritarian based arguments do not mean squat to some people either.

On the other hand being freindly in the course of a discusson is always appreciated on this board.

 

[CraigAClark]

Pretty words do mean a lot to the people who understand them. These also tend to be the same people who understand something due to the underlying theories or operational principles rather than relying on a less rigourous and sometimes logically flawed argument where something must be true because someone important said it was true. Or in other words...name dropping and authoritarian based arguments do not mean squat to some people either.

On the other hand being freindly in the course of a discusson is always appreciated on this board.

My apologies and I wasn't name dropping, I've known Mike for 20 years and once worked at Lawrence Factor. The fact remains that higher inlet temperature reduces descecant life due to the higher amount of moisture it is capable of holding in suspension. It is a fact that carbon and hopcolite loose effeciency when the zone of mass tranfer breaks through and they become wet, eventually becoming useless. The interstage separators can only trap liquid that comes out of suspension and passes on vaporous moisture. Whatever leaves the final separator has to be dealt with by the descecant. Moleseive has a greater absorbance effeciency at higher pressure, therefore the PMV.

Craig

 

[pescador775]

Craig, I'm not interested in hi-jacking your thread but since, as one of the few on SB who know something about this stuff, I thought it would be better to intervene sooner rather than later. Carry on, so far the info you provided has been generally useful.

About LF, last time I checked those guys were still offering filter tanks made of aircraft aluminum. Aircraft engineers use 7075 aircraft aluminum because it has great tensile strength and resists compressive forces. However, it does not do so well with expansive forces seen with a high pressure container. Aircraft aluminum can and does fail without warning and I know of one company that recalled every filter which they had made of that metal. They had received complaints after several explosions. I don't know how Factor gets away with it. Perhaps they make them extra thick or something. I'll get off the soapbox and let you get on with it. However, please don't cite LF as an authority. It is not credible to me, at least.

 

[VooDooGasMan]

You know I dont have all the facts down on filtration. My process is I have a small bank system Never let to under 2500 psi, I fill with bank to 2500 top off with compressore, Common sense tells me the cooler I run it the less moisture builds up, Change oil alot also Its cheap.

It will be interesting to read this thread from other Experience filtration experts so to say.

 

[CraigAClark]

Craig, I'm not interested in hi-jacking your thread but since, as one of the few on SB who know something about this stuff, I thought it would be better to intervene sooner rather than later. Carry on, so far the info you provided has been generally useful.

About LF, last time I checked those guys were still offering filter tanks made of aircraft aluminum. Aircraft engineers use 7075 aircraft aluminum because it has great tensile strength and resists compressive forces. However, it does not do so well with expansive forces seen with a high pressure container. Aircraft aluminum can and does fail without warning and I know of one company that recalled every filter which they had made of that metal. They had received complaints after several explosions. I don't know how Factor gets away with it. Perhaps they make them extra thick or something. I'll get off the soapbox and let you get on with it. However, please don't cite LF as an authority. It is not credible to me, at least.

What were the circumstances of the failure(s)? I know of one instance where O2 some how (more than likely a "home built" system with out proper safety features incorporated) back flowed into the tower. An explosion occured, vaporizing the "sight-glass". BTW, L. Factor doesn't make the towers, they are manufactured by someone else. I'm curious to know if the instances you mention, occured after the recommended cycle life of the tower or if a molesieve generated in tower fire occured? Ever entertain that the info you base your opinion on might be a bit one sided in favor of the "end user"? I've talked to many folks that tell me " how they built something", only to shudder at their ineptitude and wonder how they have survived this long without incedent.

Again, I apologise. I had an emotional reaction, which I normally don't succumb to.

Craig

 

[pescador775]

Below is one of several cautions pertaining to 7075. I will look into specific incidents but don't expect a quick response, non disclosure agreements and so forth. About 13X, don't get it wet as can happen if a filter is not drained in a timely fashion. The dessicant will overheat and cause the pressure vessel to explode. Two incidents which I am familiar with. Yeah, I know Factor uses suppliers for their hardware. I should have mentioned it to avoid questions.
Safety Circular 14.06.2002