View Full Version : 404A vs. 507

10-12-2005, 07:41 PM
Am going to install my walk-in freezer this week. Will be using a 2DL3-040E-TFC-200 discus compressor. The condenser indicates that 404A should be the refrigerant used. Can I use R507 and get an efficiency gain. Are these refrigerants interchangeable?


11-12-2005, 01:28 AM
Yes, they are interchangeable. R507 has a slight advantage on efficiency, but it is meaningless in practical matters such as kilowatt usage.

11-12-2005, 02:48 PM
I have found that 507, being a true azeotrope, is much more stable than 404A. In my experience I found that the "blends" can do some strange things under certain conditions. Most of our esteemed collegues tend to just "top off" charges rather than recover and recharge with "virgin" refrigerant. I once worked on a 40 ton A/C unit, open belt drive, with Carrier compressors with pressure activated unloaders. When I was called in the unit was on its fourth set of valve plates and had blown the discharge line out of the service valve. After some research I found that the previous company had replaced the R-12 refrigerant with MP39, a blend. After doing some analysis we found that at a point in the operation the unit was unloading and under certain temperature / pressure conditions the refrigerant in the suction line was rapidly converting back to liquid form. This is the major reason I like azeotropes over blends. I have never had a problem with 507 and have been using it for years. Most of my suppliers used to call me Mr. 507 because I was using it when most people didn't know of its existence. I also like 409A for replacing R-12, even though it is a blend, I have had alot of luck with it.

Good luck,


11-12-2005, 03:21 PM
I to prefer the 500 series refrigerant as tey are true azetrops. All of the 400 series are blends and each exhibits varying amounts of "glide". I addition, as you have a leak and recharge a 400 series refrigerant, you will change the physical properties as you do not recharge the same component mixture as you leaked out.

I personally wish the industry would just move away from the 400 series.


12-12-2005, 04:09 AM
Do I have to change anything ( expansion valves, etc.) if they specifically say for 404A use and I want to use 507 instead?


13-12-2005, 03:02 PM
Most expansion valves are marked 404A and 507. Under most circumstances the refrigerant is interchangable with the valve. Just do yourself a favor and check the superheat to insure it is with limits.