I’m sorry but you’re giving information for those junk useless machines sold on Ebay and Amazon. Real medical grade oxygen concentrators don’t fall off to 30% at 5LPM they hold >90%. Real 5LPM machines will hold >90% at 5LPM, 10LPM machines >90% at 10 LPM. All 100% of Amazon listings are filled with junky crap that drop to around 30% at 5LPM and are really only 1LPM machines with a few 1.5LPM machines at higher prices.

Anyone in the USA buying an oxygen concentrator on Ebay or Amazon should know that almost 100% of the listings are products that will never give you anything near what a devilbiss, invacare, philips respironics, companion or other medical grade oxygen concentrator put out. Yes you can get 90-95% at 1 LPM but that’s it. Any higher setting is just diluting that 1lpm down with normal 20.95% air. Any oxygen concentrator that draws a 90-130 watts is junk and will supply only about 1 extra liter per minute of 90% O2, Even if it claims 5L or 9L. 1LPM really won’t do much for you. The best I’ve seen is caps at 1.5L per minute unless it’s a true medical unit. I added a graph column to this chart so you can understand the fraud being played on everyone. https://ibb.co/2Z2mHMb If you buy a machine you have to verify the upper rating. 5L should be >90% at 5LPM if it says 30% at 5LPM it’s junk. You might think 30% is ok but it’s not see my chart and note how little it puts out compared to a real 5L unit. When you add in the 20.95% that’s in air a realizing you’re drawing in 8-12 LPM (at rest) that 30% will wash down to 24-26%. That’s not much more than normal air at 20.95%.

If a O2 concentrator were really capable of 5 liters per minute at >90% they would draw about 350-450 watts. The 10 Liter per minute machines draw 600-720 watts. If you have a 90-130 Watt machine it’s going to perform like crap and give you about 1 extra LPM of O2. everything higher produces no more O2. No miracle in efficiency has been made to O2 concentrator compressor or Zeolite sieve bed efficiency for these cheap China units to do what $1000-$2000 medical units do at 3-7 times the wattage. Ebay and Amazon ban medical grade machines and there are zero medical grade listings you will find on Amazon unless you have a business account. Example of a real medical grade machine https://www.amazon.com/Invacare-IRC5PO2V-Perfecto2-Oxygen-Concentrator/dp/B00427J9TK/ and those clowns giving it a 1 star review never bought the unit. Unverified. Ebay has 3-10 units listed but they are also banned so you have to know the unbanned keywords to find them. Also real medical grade units can run 20,000 hours without a problem. You’ll be lucky to get 500-2000 on those $250 Amazon units. I’m not knocking China units as they also make Real medical grade units but for some reason they just aren’t marketed on amazon and Ebay. You can see some real medical grade units made in China here. https://www.alibaba.com/trade/search?fsb=y&IndexArea=product_en&CatId=&SearchText=oxygen+concentrator

Look at the wattage of the more expensive units compared to the junk units the keyword "MEDICAL” in the listing is critical. Weight is also a giveaway. If it’s a 5LPM unit that’s 10-15 pounds it’s junk. Real 5-10LPM units are 40-60 pounds.

Also Don’t trust those $2K-$3k Inogen portable machines. They are run by con men. Even the top of the line $3000 G5 only puts out a max of 1.26 LPM at its highest setting. Right from the G5 manual. QUOTE: "Total Volume per Minute (ml/ min)210, 420, 630, 840, 1050, 1260"