Warning: DSV grease and check valves

Drmike · 7th September 2007, 04:11

Boris dsv is o-ring free relying on the tight fit between barrel and bore to give the seal. Thick(est) grease is needed to help the seal.

Mine needs a lot of grease to seal and needs to be applied regularly.

I just opened my dsv and noted the check valve was not seating properly. See pic below. The dsv grease had workled its way to the edges of the check valve seats and built up compressed and solidified into suirprisingly hard lumps around the ridge of the check valves. The check valves dont fully sit flat. When you suck a hard vacuum (test) it does but normal breathing it stays puckered.

After cleaning out the hardened grease it seals flat again.

Dont know if this could be a safety issue - but suspect it could become one if left.

Bottom line is go sparing on the grease and/or clean out the dsv regularly...or factory needs to improve the fit (so less greasing is needed)

pics:
-Hardened grease built up around check valve seat rim
-Resultant puckered check valve

Chris · 7th September 2007, 06:34

Mike
Are you using Christolube ?
I have seen this so often with this grease, gums up First stages as well, if you get any working its way onto the seat or poppet it makes for a nasty IP leak.

Have now moved to SP400 as it does not go hard and lumpy like Christolube does.

I can send you some Chrisolube if you like, its the goods

Cheers
Chris

***Decodiver*** · 7th September 2007, 16:21

Hi Mike,

I guess I am lucky but I just use a small amount of silicon grease and the thing works for months and months without leaking........

I guess like everything tolerances vary.

Thanks for sharing this though, it is extremely valid.

Cheers,

Dave.

Joe Botz · 8th September 2007, 19:17

Has anyone experience with DuPont Krytox?

Skipbreather · 9th September 2007, 05:00

Quote: (Originally Posted by Joe Botz)

Has anyone experience with DuPont Krytox?

I’ve been using it for years. I’ve lubed everything from regs to BOV to booster with it and not one single problem. Ever. Stays soft & slickery w/ nary a lump. Less expensive than Christolube and can be bought on line from McMaster-Carr.

Question for Mike: Which type lube was it that caused the lumps? Was it the Superlube you mentioned in an earlier thread?

Ken

iain-hsm · 9th September 2007, 19:26

Mike

This is a well known problem with these greases in dynamic conditions and with gases. The base material for the grease is known as a perfluorinated polyester and is basically a clear liquid lubricant. We use the liquid in our high pressure oxygen compressor designs it’s just a very heavy clear thick water like liquid. The base material is expensive at just over £100 per kilo and is used in oxygen compressors etc, but the design has to be suitable for the product application.

To change from the clear base liquid and to make a useable grease the manufacturer adds a bulk filler material of which there are a number of types. Each filler and oil combination have there own BAM test rating or oxygen ignition temperature so the manufacturer chooses the lubricant type from the required lubrication properties and BAM number for the oxygen application.

In your case the bulk filler is pure simple talc. Excellent BAM properties as talc cannot cause a fire with oxygen but as you are finding out it’s pretty crap in your dynamic application. IMHO the supplier got it wrong with the design or didn’t know enough to make the correct call in the first place.

What you are experiencing is the perfluorinated fluid leaching out of the filler leaving the hard white talc behind. The problem is with the manufacturer using the wrong lubricant in the first place.
It is a well known with a number of documented cases in industry and offshore. This is known as lubricant wash out.

The pure liquid base has a number of interesting properties including the ability to turn normalized white PTFE pipe tape clear. The problem with our scuba industry is we latched onto marketed brand names without fully understanding the tribology properties of the material in the first place.

One other point would be the material you are tying to lubricate, some plastics like Delrin etc are extremely poor choices for underwater applications difficult to hold manufacture tolerance due to temperature expansion, notorious for creep under pressure and hydraulic conditions, a combination of both can lead to lubrication failure. Tribology is the study of wear tear and friction of materials under load. Regards Iain Middlebrook.

graham_hk · 10th September 2007, 00:58

Quote: (Originally Posted by iain-hsm)

Mike

This is a well known problem with these greases in dynamic conditions and with gases. The base material for the grease is known as a perfluorinated polyester and is basically a clear liquid lubricant. We use the liquid in our high pressure oxygen compressor designs it’s just a very heavy clear thick water like liquid. The base material is expensive at just over £100 per kilo and is used in oxygen compressors etc, but the design has to be suitable for the product application.

To change from the clear base liquid and to make a useable grease the manufacturer adds a bulk filler material of which there are a number of types. Each filler and oil combination have there own BAM test rating or oxygen ignition temperature so the manufacturer chooses the lubricant type from the required lubrication properties and BAM number for the oxygen application.

In your case the bulk filler is pure simple talc. Excellent BAM properties as talc cannot cause a fire with oxygen but as you are finding out it’s pretty crap in your dynamic application. IMHO the supplier got it wrong with the design or didn’t know enough to make the correct call in the first place.

What you are experiencing is the perfluorinated fluid leaching out of the filler leaving the hard white talc behind. The problem is with the manufacturer using the wrong lubricant in the first place.
It is a well known with a number of documented cases in industry and offshore. This is known as lubricant wash out.

The pure liquid base has a number of interesting properties including the ability to turn normalized white PTFE pipe tape clear. The problem with our scuba industry is we latched onto marketed brand names without fully understanding the tribology properties of the material in the first place.

One other point would be the material you are tying to lubricate, some plastics like Delrin etc are extremely poor choices for underwater applications difficult to hold manufacture tolerance due to temperature expansion, notorious for creep under pressure and hydraulic conditions, a combination of both can lead to lubrication failure. Tribology is the study of wear tear and friction of materials under load. Regards Iain Middlebrook.

Interesting and typical of the dive industry

I have experienced Delrin swelling at increased temperature - I wonder, what do you recommend as a replacement for the ever present Delrin.

Graham

Drmike · 10th September 2007, 03:10

Quote: (Originally Posted by iain-hsm)

Mike

This is a well known problem with these greases in dynamic conditions and with gases. The base material for the grease is known as a perfluorinated polyester and is basically a clear liquid lubricant. We use the liquid in our high pressure oxygen compressor designs it’s just a very heavy clear thick water like liquid. The base material is expensive at just over £100 per kilo and is used in oxygen compressors etc, but the design has to be suitable for the product application.

To change from the clear base liquid and to make a useable grease the manufacturer adds a bulk filler material of which there are a number of types. Each filler and oil combination have there own BAM test rating or oxygen ignition temperature so the manufacturer chooses the lubricant type from the required lubrication properties and BAM number for the oxygen application.

In your case the bulk filler is pure simple talc. Excellent BAM properties as talc cannot cause a fire with oxygen but as you are finding out it’s pretty crap in your dynamic application. IMHO the supplier got it wrong with the design or didn’t know enough to make the correct call in the first place.

What you are experiencing is the perfluorinated fluid leaching out of the filler leaving the hard white talc behind. The problem is with the manufacturer using the wrong lubricant in the first place.
It is a well known with a number of documented cases in industry and offshore. This is known as lubricant wash out.

The pure liquid base has a number of interesting properties including the ability to turn normalized white PTFE pipe tape clear. The problem with our scuba industry is we latched onto marketed brand names without fully understanding the tribology properties of the material in the first place.

One other point would be the material you are tying to lubricate, some plastics like Delrin etc are extremely poor choices for underwater applications difficult to hold manufacture tolerance due to temperature expansion, notorious for creep under pressure and hydraulic conditions, a combination of both can lead to lubrication failure. Tribology is the study of wear tear and friction of materials under load. Regards Iain Middlebrook.

Thanks Ian thats interesting and useful info. Didnt know about the whole talc thing. To be fair though the Mnf uses some very thick clear lubricant (looks like vaseline) not the white stuff. In the field I tend to use whatever people around me have so I have used all sorts of stuff including the white grease thats likely caused the problem.

Thanks again - I shall stear well clear of the non clear greases in the future.
The thick clear grease (loctite) I used before is no longer supplied to Singapore for some reason so looking for an alternative - any recomendations??

Cheers
Mike

iain-hsm · 12th September 2007, 16:52

Quote: (Originally Posted by Drmike)

Thanks Ian thats interesting and useful info. Didnt know about the whole talc thing. To be fair though the Mnf uses some very thick clear lubricant (looks like vaseline) not the white stuff. In the field I tend to use whatever people around me have so I have used all sorts of stuff including the white grease thats likely caused the problem.

Thanks again - I shall stear well clear of the non clear greases in the future.
The thick clear grease (loctite) I used before is no longer supplied to Singapore for some reason so looking for an alternative - any recomendations??

Cheers
Mike

Mike.
I can’t claim I know about your mouthpiece tests specifically but if as the manufacturer claims it has been supplied to the military then they should have tested the mouthpiece to the mil-spec standard and should be able to produce the independent test report and the lubricant spec. I guess this has never been done.

For interest the mil-spec test on the HSM mouthpiece design was to 4000 open and closed cycles.

A sample batch is taken at random and the open to close torque is measured to be within tolerance. The mouthpiece is connected to a test rig hose and pressurized to 500mm water gauge. It is then submerged in (artificial) sea water and cycled open/closed just once. Then out of water but wet 10 times. We repeat this process again wet/dry 10 more times then test for leaks.

This process is repeated again for a total of 200 cycles then the open/close torque is measured.
This goes on until 4000- cycles is completed and the unit is stripped down and inspected.

Failure point is either any leak in the mouthpiece during test or an increase in the open/close torque. FYI our torque increase was under 3inch/lbs and it passed. One thing we found is torque increased when the mouthpiece was new but decreased when over the 1000/2000 cycles possible due to “polishing” of the contact area.

In the mil-spec a typical dive plan estimates that the mouthpiece is cycled at most six times, and on each diving set an average of 60 dives per year is undertaken before servicing. So if tested to Mil-spec you would get 360 operational cycles to the 4000 tested cycles a conservative 11.1 safety ratio for the critical life support parts. i.e The thing don’t leak. Iain Middlebrook

iain-hsm · 12th September 2007, 17:10

Quote: (Originally Posted by graham_hk)

Interesting and typical of the dive industry

I have experienced Delrin swelling at increased temperature - I wonder, what do you recommend as a replacement for the ever present Delrin.

Graham

Hi Graham.
Now then! dont tar us all with that brush, the dive industry as you put it is the sports diving market and no better that the toy industry, except they make fewer parts and not as much fun to be involved in.

The dive industry I work in is much more fun. as we have much more expensive things to bust, loose, at let go rusty!

Now regarding Delrin, for sports use I dont know maybe OK its cheap and easy to machine maybe OK if you just want a sports product with no traceable repeatable test standard, but for the commercial and military markets they really dont like it, in fact they prefer to have the plastic parts moulded.

As for what type to use it really is impossible to say as each part and market requires a different property, strength, elongation, deflection water absorbsion, oxygen compatability, hardness, impact resistance, drop test, bomb test, where do you want me to end? Take a typical diving 2nd stage for example 3 different moulded polymers and two rubber compounds minimum. iain.

7th September 2007, 06:34	#2 (permalink)
Chris Go Nude Or Go Home Current Rebreather/s: Megalodon Other Rebreather/s: Inspiration Classic Megalodon Prism Topaz Sport Kiss Join Date: Feb 2005 Location: Perth, Western Australia Posts: 609	Re: Warning: DSV grease and check valves Mike Are you using Christolube ? I have seen this so often with this grease, gums up First stages as well, if you get any working its way onto the seat or poppet it makes for a nasty IP leak. Have now moved to SP400 as it does not go hard and lumpy like Christolube does. I can send you some Chrisolube if you like, its the goods Cheers Chris __________________ Megalodon Sorb and Sensors whilst in Australia www.divetub.com.au Diving & Photography @ www.uwphotog.com
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7th September 2007, 16:21	#3 (permalink)
*Decodiver* Administrator Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jan 2005 Location: Geneva Posts: 2,181	Re: Warning: DSV grease and check valves Hi Mike, I guess I am lucky but I just use a small amount of silicon grease and the thing works for months and months without leaking........ I guess like everything tolerances vary. Thanks for sharing this though, it is extremely valid. Cheers, Dave. __________________ CCR/OC Trimix Instructor Trainer CCR Training to Mixed Gas in Switzerland, France, UK & Germany on Megalodon/COPIS-Megalodon/KISS/Sport KISS/Ouroboros/rEvo/Inspiration/Evolution/Sentinel www.zerogravitydiving.com Rebreather World Terms & Conditions
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8th September 2007, 19:17	#4 (permalink)
Joe Botz New Member Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Aug 2005 Location: USA, NY Posts: 41	Re: Warning: DSV grease and check valves Has anyone experience with DuPont Krytox?
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9th September 2007, 05:00	#5 (permalink)
Skipbreather Reads the fine print Current Rebreather/s: Megalodon Home Build Other Rebreather/s: Not Bought Yet MK 15.X Home Build Join Date: Mar 2005 Location: Chicago, Illinois, USA Posts: 557	Re: Warning: DSV grease and check valves Quote: (Originally Posted by Joe Botz) Has anyone experience with DuPont Krytox? I’ve been using it for years. I’ve lubed everything from regs to BOV to booster with it and not one single problem. Ever. Stays soft & slickery w/ nary a lump. Less expensive than Christolube and can be bought on line from McMaster-Carr. Question for Mike: Which type lube was it that caused the lumps? Was it the Superlube you mentioned in an earlier thread? Ken __________________ "Entropy RULES! Enjoy the interim."
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9th September 2007, 19:26	#6 (permalink)
iain-hsm Custom Title Allowed! Current Rebreather/s: MK 15.X Other CCR Other SCR Other Rebreather/s: Other CCR Other SCR Join Date: Mar 2005 Location: Loughborough England uk Posts: 347	Re: Warning: DSV grease and check valves Mike This is a well known problem with these greases in dynamic conditions and with gases. The base material for the grease is known as a perfluorinated polyester and is basically a clear liquid lubricant. We use the liquid in our high pressure oxygen compressor designs it’s just a very heavy clear thick water like liquid. The base material is expensive at just over £100 per kilo and is used in oxygen compressors etc, but the design has to be suitable for the product application. To change from the clear base liquid and to make a useable grease the manufacturer adds a bulk filler material of which there are a number of types. Each filler and oil combination have there own BAM test rating or oxygen ignition temperature so the manufacturer chooses the lubricant type from the required lubrication properties and BAM number for the oxygen application. In your case the bulk filler is pure simple talc. Excellent BAM properties as talc cannot cause a fire with oxygen but as you are finding out it’s pretty crap in your dynamic application. IMHO the supplier got it wrong with the design or didn’t know enough to make the correct call in the first place. What you are experiencing is the perfluorinated fluid leaching out of the filler leaving the hard white talc behind. The problem is with the manufacturer using the wrong lubricant in the first place. It is a well known with a number of documented cases in industry and offshore. This is known as lubricant wash out. The pure liquid base has a number of interesting properties including the ability to turn normalized white PTFE pipe tape clear. The problem with our scuba industry is we latched onto marketed brand names without fully understanding the tribology properties of the material in the first place. One other point would be the material you are tying to lubricate, some plastics like Delrin etc are extremely poor choices for underwater applications difficult to hold manufacture tolerance due to temperature expansion, notorious for creep under pressure and hydraulic conditions, a combination of both can lead to lubrication failure. Tribology is the study of wear tear and friction of materials under load. Regards Iain Middlebrook.
(Offline)

10th September 2007, 00:58	#7 (permalink)
graham_hk Custom Title Allowed! Current Rebreather/s: RB80 / Clone Other Rebreather/s: Inspiration Classic Classic Kiss MK 15.X RB80 / Clone Join Date: Nov 2005 Location: Philippines Posts: 106	Re: Warning: DSV grease and check valves Quote: (Originally Posted by iain-hsm) Mike This is a well known problem with these greases in dynamic conditions and with gases. The base material for the grease is known as a perfluorinated polyester and is basically a clear liquid lubricant. We use the liquid in our high pressure oxygen compressor designs it’s just a very heavy clear thick water like liquid. The base material is expensive at just over £100 per kilo and is used in oxygen compressors etc, but the design has to be suitable for the product application. To change from the clear base liquid and to make a useable grease the manufacturer adds a bulk filler material of which there are a number of types. Each filler and oil combination have there own BAM test rating or oxygen ignition temperature so the manufacturer chooses the lubricant type from the required lubrication properties and BAM number for the oxygen application. In your case the bulk filler is pure simple talc. Excellent BAM properties as talc cannot cause a fire with oxygen but as you are finding out it’s pretty crap in your dynamic application. IMHO the supplier got it wrong with the design or didn’t know enough to make the correct call in the first place. What you are experiencing is the perfluorinated fluid leaching out of the filler leaving the hard white talc behind. The problem is with the manufacturer using the wrong lubricant in the first place. It is a well known with a number of documented cases in industry and offshore. This is known as lubricant wash out. The pure liquid base has a number of interesting properties including the ability to turn normalized white PTFE pipe tape clear. The problem with our scuba industry is we latched onto marketed brand names without fully understanding the tribology properties of the material in the first place. One other point would be the material you are tying to lubricate, some plastics like Delrin etc are extremely poor choices for underwater applications difficult to hold manufacture tolerance due to temperature expansion, notorious for creep under pressure and hydraulic conditions, a combination of both can lead to lubrication failure. Tribology is the study of wear tear and friction of materials under load. Regards Iain Middlebrook. Interesting and typical of the dive industry I have experienced Delrin swelling at increased temperature - I wonder, what do you recommend as a replacement for the ever present Delrin. Graham
(Offline)

10th September 2007, 03:10	#8 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,323	Re: Warning: DSV grease and check valves Quote: (Originally Posted by iain-hsm) Mike This is a well known problem with these greases in dynamic conditions and with gases. The base material for the grease is known as a perfluorinated polyester and is basically a clear liquid lubricant. We use the liquid in our high pressure oxygen compressor designs it’s just a very heavy clear thick water like liquid. The base material is expensive at just over £100 per kilo and is used in oxygen compressors etc, but the design has to be suitable for the product application. To change from the clear base liquid and to make a useable grease the manufacturer adds a bulk filler material of which there are a number of types. Each filler and oil combination have there own BAM test rating or oxygen ignition temperature so the manufacturer chooses the lubricant type from the required lubrication properties and BAM number for the oxygen application. In your case the bulk filler is pure simple talc. Excellent BAM properties as talc cannot cause a fire with oxygen but as you are finding out it’s pretty crap in your dynamic application. IMHO the supplier got it wrong with the design or didn’t know enough to make the correct call in the first place. What you are experiencing is the perfluorinated fluid leaching out of the filler leaving the hard white talc behind. The problem is with the manufacturer using the wrong lubricant in the first place. It is a well known with a number of documented cases in industry and offshore. This is known as lubricant wash out. The pure liquid base has a number of interesting properties including the ability to turn normalized white PTFE pipe tape clear. The problem with our scuba industry is we latched onto marketed brand names without fully understanding the tribology properties of the material in the first place. One other point would be the material you are tying to lubricate, some plastics like Delrin etc are extremely poor choices for underwater applications difficult to hold manufacture tolerance due to temperature expansion, notorious for creep under pressure and hydraulic conditions, a combination of both can lead to lubrication failure. Tribology is the study of wear tear and friction of materials under load. Regards Iain Middlebrook. Thanks Ian thats interesting and useful info. Didnt know about the whole talc thing. To be fair though the Mnf uses some very thick clear lubricant (looks like vaseline) not the white stuff. In the field I tend to use whatever people around me have so I have used all sorts of stuff including the white grease thats likely caused the problem. Thanks again - I shall stear well clear of the non clear greases in the future. The thick clear grease (loctite) I used before is no longer supplied to Singapore for some reason so looking for an alternative - any recomendations?? Cheers Mike __________________ Cave diving is a sport Wreck diving is a sport Diving in general is a sport 'Rebreather diving' is not a sport its the delusional obsession with a highly dangerous and often inappropriate piece of equipment Last edited by Drmike : 10th September 2007 at 04:13.
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12th September 2007, 16:52	#9 (permalink)
iain-hsm Custom Title Allowed! Current Rebreather/s: MK 15.X Other CCR Other SCR Other Rebreather/s: Other CCR Other SCR Join Date: Mar 2005 Location: Loughborough England uk Posts: 347	Re: Warning: DSV grease and check valves Quote: (Originally Posted by Drmike) Thanks Ian thats interesting and useful info. Didnt know about the whole talc thing. To be fair though the Mnf uses some very thick clear lubricant (looks like vaseline) not the white stuff. In the field I tend to use whatever people around me have so I have used all sorts of stuff including the white grease thats likely caused the problem. Thanks again - I shall stear well clear of the non clear greases in the future. The thick clear grease (loctite) I used before is no longer supplied to Singapore for some reason so looking for an alternative - any recomendations?? Cheers Mike Mike. I can’t claim I know about your mouthpiece tests specifically but if as the manufacturer claims it has been supplied to the military then they should have tested the mouthpiece to the mil-spec standard and should be able to produce the independent test report and the lubricant spec. I guess this has never been done. For interest the mil-spec test on the HSM mouthpiece design was to 4000 open and closed cycles. A sample batch is taken at random and the open to close torque is measured to be within tolerance. The mouthpiece is connected to a test rig hose and pressurized to 500mm water gauge. It is then submerged in (artificial) sea water and cycled open/closed just once. Then out of water but wet 10 times. We repeat this process again wet/dry 10 more times then test for leaks. This process is repeated again for a total of 200 cycles then the open/close torque is measured. This goes on until 4000- cycles is completed and the unit is stripped down and inspected. Failure point is either any leak in the mouthpiece during test or an increase in the open/close torque. FYI our torque increase was under 3inch/lbs and it passed. One thing we found is torque increased when the mouthpiece was new but decreased when over the 1000/2000 cycles possible due to “polishing” of the contact area. In the mil-spec a typical dive plan estimates that the mouthpiece is cycled at most six times, and on each diving set an average of 60 dives per year is undertaken before servicing. So if tested to Mil-spec you would get 360 operational cycles to the 4000 tested cycles a conservative 11.1 safety ratio for the critical life support parts. i.e The thing don’t leak. Iain Middlebrook
(Offline)

12th September 2007, 17:10	#10 (permalink)
iain-hsm Custom Title Allowed! Current Rebreather/s: MK 15.X Other CCR Other SCR Other Rebreather/s: Other CCR Other SCR Join Date: Mar 2005 Location: Loughborough England uk Posts: 347	Re: Warning: DSV grease and check valves Quote: (Originally Posted by graham_hk) Interesting and typical of the dive industry I have experienced Delrin swelling at increased temperature - I wonder, what do you recommend as a replacement for the ever present Delrin. Graham Hi Graham. Now then! dont tar us all with that brush, the dive industry as you put it is the sports diving market and no better that the toy industry, except they make fewer parts and not as much fun to be involved in. The dive industry I work in is much more fun. as we have much more expensive things to bust, loose, at let go rusty! Now regarding Delrin, for sports use I dont know maybe OK its cheap and easy to machine maybe OK if you just want a sports product with no traceable repeatable test standard, but for the commercial and military markets they really dont like it, in fact they prefer to have the plastic parts moulded. As for what type to use it really is impossible to say as each part and market requires a different property, strength, elongation, deflection water absorbsion, oxygen compatability, hardness, impact resistance, drop test, bomb test, where do you want me to end? Take a typical diving 2nd stage for example 3 different moulded polymers and two rubber compounds minimum. iain.
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