Data centers with air cooled Computer Room AC (CRAC) units contain large amounts of refrigerant within the cooling systems. Maintenance costs for data center CRAC units are typically the highest costs incurred by data center managers. For facilities using R-22, these costs are increasing exponentially and will continue to rise until R-22 is phased out on January 1, 2020. After the phase out, even legacy equipment will be unable to obtain R-22.
While existing legacy CRAC systems can continue to operate with R-22 until the system reaches “End of Life” (EOL), the problem occurs when an equipment failure such as a compressor burn out or a piping leak happens and a total replacement of refrigerant is required. A 20-ton CRAC unit can have 50-100 pounds of refrigerant, thus the use of R-22 may be cost prohibitive prior to the phase out. With R-22 costs high, the value of reclaimed material can offset retrofit costs. Again, R-22 will not be an option after 2020 so ensure you have a solution in place.
One solutions is to proactively convert the system to the refrigerant R-407c. R-407c has similar properties to R-22 and will provide adequate cooling capacities.
There are several basic procedures to follow with the conversion which include but are not limited to the following:
- All the refrigerant must be replaced. R-22 and R-407c cannot be mixed.
- Any brazing hot work should only be performed with a nitrogen bleed in the refrigerant piping system.
- All corrective procedures are to be completed that caused the refrigerant replacement.
- All refrigerant filters are to be replaced.
- Existing mineral oil in compressor(s) is to be removed and replaced with Polyol Ester (POE) oil.
- Note that POE oil is very hygroscopic and will quickly absorb moisture from the air. The refrigerant system is to be sealed from the open environment immediately after adding the POE lubricant.
- Refrigerant piping system is to be pressure tested at 250 psig minimum for 72 hours, if the room
conditions allow. - A vacuum should be pulled down to 400-micron minimum.
- Refrigerant total charge should be calculated and 80% charged with liquid only in the liquid circuit. R-
407c is a refrigerant that cannot be charged with vapor. Proper stemps should be taken when finalizing the charge
through the suction valve to avoid compressor damage. - Check and record operating parameters such as superheat and sub-cooling.
The cost of R-22 will continue to rise until its end of life in 2020, thus data center managers should look at R-407c as a viable alternative in reducing maintenance costs. With manufactures shipping new units with R-407c in lieu of R-22, you can be assured that the conversion is indeed proper. As with all aspects of your data center, ensure that you have an experienced contractor familiar with mission critical sites. The high cost of R-22 has resulted in the dangerous use of counterfeit refrigerant as well as negligent use of improper refrigerants. Read our post regarding the dangers of counterfeit refrigerant use in data centers and contact Keystone Critical Systems for more information.
