View Full Version : R290 and yellow sight glass

29-05-2014, 12:16 AM
Hi guys I have come across several Hydrocarbon units with yellow sight glass's from new / commissioning have been told that its a reaction with the R290 and not a moisture fault, has anyone come across this before,

On the systems I have had to pull down for repair in the past I have cleared and returned the sight glass's back to green after purging with OFN and vac, but on this particular Pack just about 8 weeks old I'm told by manufacture its a reaction with the R290 refrigerant and the sight glass

any views


29-05-2014, 10:10 AM
If turn back to green after OFN and vac is not problem with sight-glas and washed away dye, and i agree you (non written here) suspect they filling with non proper dryed R290 and/or put in some ppm methanol in R290 to make non freezing water droplets if they have problem with high water content in R290 - or they not using dryer or already water saturated dryer (to small size or bad handling with open end on air long time or R290 with high water content saturate dryer-filter)

Hummidity-sensor in sight-glas can rought descibed as yellow-dyed filling materia blend with coboltcloride dyed silicagel as in the dryed status are blue and with combination of yellow dyed filling material show green sign.

around 6-8% water content in silicagel-part (can adjust around little depend of filling material), color start to shifting from blue via magenta to pink color and going to color-less in higher water content or in sight-glass with yellow inked filling material, going from gren (some time blue) to yellow (somtime via magenta/pink to near colorless)

Liquid propane (R290) itself carrier very little water and drops of water rolling in liquid part can build allready at 25 ppm level on water on 1 degree C (and later possibly freeze up TXV), but propanes embedded avoid of water, make very easy for dryer-filter to dry up propane liquid to proper level, compare to drying up HCF-refigerant as act as liquid dryer itself.

So if you have working filterdryer, you should not have problem with high water content in R290 and also green sign in sight glasses.

In your case, I trying replace drier-filter and see if sightglass going back to green again, and with work on more than one machine - this are commission error depend of not proper handling of equipment and let air humidity wet up both inside equipment and inside used mainfold with hoses and/or using low grade and wet R290 (BBQ-propane with methyl alchol as freeze protect?...)

09-06-2014, 10:57 PM
Thanks for your reply, The manufacture insists they have a vey strict pressure test and dehydration program, personally I think there is a problem but they insist its a reaction with the R290 and R1270, I cant touch it until it has a problem then will change dryer and or give it a 24hr vac