Lubricant for medical oxygen concentrators ?

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Hello from New Zealand :)

We service about 300 medical oxygen concentrators and I'm wondering if someone can recommend a grease or lubricant for the valve block used in the oxygen concentrators.

This is the type of concentrator.

https://www.med-electronics.com/Pla...ncentrator-with-SensO-p/inv-irc5lxo2.htm

And hopefully this link will show a picture of the valve block.

https://o2crs.com/product/4way-valve-invacare/

Inside the valve are 2 ceramic slider blocks, very similar to a couple of dominoes that have strategic ports and when the pressure rises to 35 PSI they slide over each other, maybe 3-4mm ? and about once every 5 seconds.

A common problem is after 10,000 hours (about 3 years), the lubricant between the sliders has dried and the valve block sticks, causing the concentrator to fail.

We can remove and clean the sliders and have tried a range of lubricants, but in general none seems much better than the others and they still dry out.

The output from the compressor is warm, maybe 35*c ? and flows at about 30 litres per minute, so a fair bit of warm air blows continuously over the sliders and lubricant.

Any suggestions on a thin, warm air tolerant, non-drying lubricant ?

Cheers,
 
Any information from the manufacturer ?

I know , on the oxygen regulator & gauge for a torch , you have to be careful about oils / lubercants / grease to avoid fire .
 
I certainly hope you're planning to consult a medical device tribologist.

In the USA, replacement parts (and the maintenance components) all fall under the rules of US CFR-21 and guidelines of ISO 13485. The maintenance manual for the device should be consulted. If the manual is not available, you'll need to reverse engineer the specifications, select a lubricant then, apply for a 510k medical device certificate.

Speaking as a former director of engineering for a medical device company, I would highly recommend that you do not "take a guess" about the right lubricant to use and do not put this into production until your testing standards have been met.
 
Originally Posted by RayCJ

I certainly hope you're planning to consult a medical device tribologist.

In the USA, replacement parts (and the maintenance components) all fall under the rules of US CFR-21 and guidelines of ISO 13485. The maintenance manual for the device should be consulted. If the manual is not available, you'll need to reverse engineer the specifications, select a lubricant then, apply for a 510k medical device certificate.

Speaking as a former director of engineering for a medical device company, I would highly recommend that you do not "take a guess" about the right lubricant to use and do not put this into production until your testing standards have been met.



For sure.

Whatever the lubricant is, it has be be similar to conform to an H1 of H3 lubricant.

Under CFR 21 21CFR178.3570

only certain additives are allowed and they range from 0.5 to 10 ppm.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=178.3570

The actual base oils are either Medical White Oils, PAOs, PAG's, esters, or silicones, depending on the application:

https://www.bechem.de/en/lubricants...cessing-and-pharmaceutical-industry.html

The Oils must be certified:

Before Using Food Grade Lubricants equipment users should check the following:

The Material Safety Data Sheet (MSDS)
Testing of the lubricant for disburden
The Ingredients should comply with the 21 CFR part 178:3570
The lubricant has a current Certificate of Analysis
Lubricants must not have an expired use by date.
 
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Oh, and BTW, Hi there and Welcome... So sorry for not saying hi in my first post. Just got home from work and was still in "serious mode".

If that generator is still under patent of the manufacturer and if you're not a licensed/certified repair center, the repair guide will be difficult to obtain. You might try checking with the maintenance and certification departments of the hospitals in your clientele list.

FWIW, I doubt there there's any lubricant on those reed blocks. Look at a brand new set and analyze them very carefully. I'll bet they have a bowed shape on one side -ever so subtle. As they wear out and change shape, they fail.


Ray
 
Thank you for your welcome and replies.

I understand and agree with the rules re oils and O rings for 3,000 PSI bottles and regulators etc, but to make a long story short I've serviced these machines for decades, there is no risk whatsoever in re-lubricating the valves.

There is a far greater risk sending out a machine knowing there is a fair chance the valve will fail within the next 1-3,000 hours.

The USA manufacturer simply says 'if the valve is working it is ok, if it fails, then replace it'

These valves are working, but sure as eggs they will fail...

They are used predominantly in the home by elderly and frail patients, they don't need machines failing unnecessarily.

I know where you are all coming from, but this is New Zealand, we don't do gazillions of pointless rules and regulations, litigation, class action lawsuits, suing McDonalds for $3million because of a hot cup of coffee or Subway for $500,000 because the Sub was 10mm too short.
We just fix stuff, professionally, safely and cost effectively.
Cheers
 
Originally Posted by RayCJ
FWIW, I doubt there there's any lubricant on those reed blocks. Look at a brand new set and analyze them very carefully. I'll bet they have a bowed shape on one side -ever so subtle. As they wear out and change shape, they fail.

We have dismantled numerous brand new valves, they are flat faced and factory lubricated, made from a very hard non wearing polished ceramic. Interestingly the colour of the lube has changed from time to time, methinks the manufacturer is well aware of the problem and trying to find a solution.

Prior to us servicing these machines the hospital Biomeds were doing their own 'checking', in accordance with the USA manufacturers regulations, if it goes, it's ok, send it out.

They were experiencing a 24% failure rate, of every hundred sent out, 24% failed within in the next 3-5,000 hours.

There were numerous close calls with elderly patients being woken at 3:00am with a machine screaming an alarm, pitch black, frail, elderly, scared, petrified...

Since we have been doing the servicing the failure rate is 3%
 
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