A proper evacuation may take 15 minutes, 15 hours, or 15 days. The time allowed for decay depends upon the size of the system, but generally, 10 minutes minimum with 1 minute added per ton is a good guideline. Each of these requirements is focused on the acceptable level of moisture remaining in the system, again, because at these levels, the majority of degassing has already occurred. For these systems, consult the manufacturer if at all possible. For ultra-low-temperature refrigeration, a finishing vacuum as low as 20 microns may be required with a decay holding below 200 microns. For the system containing POE oil, like an R410a or R404a system, a finishing vacuum of 250 with a decay holding 500 microns or less should be achieved-never a decay rising over 1000 microns on an R10a system opened for service. For systems containing mineral oil like R22 systems, a finishing vacuum of 500 microns with a decay holding below 1000 microns is generally considered acceptable, whether we are talking about a new installation or a system opened for service. The following are guidelines for an acceptable standing level of vacuum. The system needs to hold below the target vacuum to assure that adequate dehydration has occurred. Core tools are essential to isolate the vacuum pump and rig from the system when the ultimate vacuum level is being measured. It is not until the vacuum has been isolated that we can determine the ultimate level of vacuum. A good vacuum rig coupled to a large pump can overpower the dehydration process, pulling below 500 but not removing the moisture, which simply takes time. Pulling below 500 microns and being below 500 microns are two totally different things. Significant levels of dehydration will not occur until the vacuum level is below 1000 microns.Īn important distinction must be made when it comes to the vacuum gauge reading and the actual vacuum level. Once you are below 5000 microns, you can be assured that dehydration is occurring and that moisture is being boiled off and removed through the evacuation process. If you cannot achieve a vacuum below 5000, it is a good indicator of a system leak, a leak in your vacuum hoses, contaminated vacuum pump oil, etc. At 5000 microns, 99.34% of the degassing has occurred, but the moisture removal is just beginning.
EVAC SYSTEM CAR PROFESSIONAL
Using an electronic micron gauge like the BluVac+ Professional and its accompanying application will show you the characteristics of moisture, allowing you to identify a wet vs. An electronic vacuum gauge is the only way to determine when the dehydration process is complete. If you want to clean (degas and dehydrate) the system properly, an accurate vacuum gauge is an indispensable component of the evacuation system. Keeping the system clean (contaminant-free), dry, and leak-free during assembly will save far more time on the back end than the uncertainty it will introduce into the time required to clean the system through the evacuation process. The best advice that can be given when it comes to evacuation is to make sure the preparation of the copper tubing is kept the primary priority. It takes heat energy and time for the bonds to break, and it takes a deep vacuum for the pump to ultimately carry that moisture out of the system.
EVAC SYSTEM CAR FREE
Moisture has strong molecular bonds and does not easily free itself from the surfaces it attaches to. Removing the air is an easy process, but moisture removal is much more difficult and simply takes time. Something more important than knowing how long an evacuation will take is understanding when the evacuation is complete. How long an evacuation takes depends on many factors in this order, including but not limited to the size of the system, the level of system contamination, the diameter and length of the vacuum hoses, the presence of the Schrader cores in the service valves, dryness of the vacuum pump oil, and the size of the vacuum pump. All of these can cause permanent damage to the refrigeration system. Moisture with oil forms sludge, and moisture with refrigerant forms hydrofluoric and hydrochloric acids. Modern-day evacuation techniques are meant to degas and dehydrate a system, cleaning it of contaminants to a level that assures that non-condensables-and more importantly, moisture-will cause no harm to the refrigerant or the refrigerant oil in the system.