O-ring material
- Thread starter sunderll
- Start date
Help Support The Rocketry Forum:
- Joined
- Jan 19, 2009
- Messages
- 14,969
- Reaction score
- 1,307
In reloads I've seen:
Black = Buna-N
Orangish-red = Silicone
All the AT reloads I've seen are black (Buna-N)
-Kevin
Black = Buna-N
Orangish-red = Silicone
All the AT reloads I've seen are black (Buna-N)
-Kevin
GregGleason
Well-Known Member
- Joined
- Nov 13, 2009
- Messages
- 4,674
- Reaction score
- 45
I would contact AeroTech to make sure.
Not only do you have to be concerned with the material, but O-rings have a durometer rating associated with them that is often tied to the material they are made from. So it could be that they are engineered to perform with a material with a specified hardness.
If I were to guess though, it would be silicone since it typically has a higher tolerance for heat applications.
Greg
Not only do you have to be concerned with the material, but O-rings have a durometer rating associated with them that is often tied to the material they are made from. So it could be that they are engineered to perform with a material with a specified hardness.
If I were to guess though, it would be silicone since it typically has a higher tolerance for heat applications.
Greg
Greg, I was with you right up to your last sentence. While silicone O-rings do have a higher temperature rating than most other common materials, Kevin gets it right when he says the silicone O-rings are a red (or red-orange) color. The problem with these are a lessening of properties when lubricated with a silicone-based material like many use.
All the AT reloads I've seen use black O-rings. The common black O-ring materials, in order of cost, are Buna-N at the low end, EPDM and Viton at the high end. These are good with silicone lubes but EPDM swells and weakens with a petroleum-based lube.
If AT will let us know, you're right; durometer is important as well as the material.
GregGleason
Well-Known Member
- Joined
- Nov 13, 2009
- Messages
- 4,674
- Reaction score
- 45
Thanks Kenn.
If I don't know something, I'll often preface my remarks with the words "guess" so that it understood that it is an opinion of a lower level of confidence. I didn't know about the color association with silicone, so that's good to know and file away in the back of my mind.
While I'm not an engineer, I often play one at home.
Greg
If I don't know something, I'll often preface my remarks with the words "guess" so that it understood that it is an opinion of a lower level of confidence. I didn't know about the color association with silicone, so that's good to know and file away in the back of my mind.
While I'm not an engineer, I often play one at home.
Greg
Binder Design
Well-Known Member
- Joined
- Jan 17, 2009
- Messages
- 1,823
- Reaction score
- 266
They are buna N, 70 durometer.
Did you have kits that were short or did you lose a couple O-rings.I save all my old o-rings (not the crispy ones).From Aero,CTI,Kosdon,Loki.Got 2 gallon bags full use them every once in awhile. And for other non rocketry things. Just inspect carefully.I even got the rings from 20 yr old loads(remember those 2 rings in forward bulkhead that were a PITA trying to seat one inside the other)
jef955
Well-Known Member
- Joined
- Apr 15, 2009
- Messages
- 255
- Reaction score
- 3
https://www.oringmonkey.com/index.php
Try these guys. I have ordered twice from them with no issues, and used their rings also with no problems. Great selection, and seems to be much cheaper than Home Depot etc..
Try these guys. I have ordered twice from them with no issues, and used their rings also with no problems. Great selection, and seems to be much cheaper than Home Depot etc..
stealth6
insert witty tagline here
On this subject - perhaps someone who's knowledgeable about such things can weigh in:
On my recent L2 cert flight, I used a Loki 54/2800 stuffed with a K350 Moonburner reload. As per Loki standards, I used a silicone (orange) o-ring for the nozzle. The burn and flight all went great with no problems (and a successful L2!), however on cleanup I found something a bit odd. That silicone o-ring was sort-of melted a bit. It was still round, and still seemed to seal just fine, but it disintegrated upon removal and there was quite a lot of orange/white residue left in the slot that had to be scraped out. I've never seen this before other post-flight O-rings, and it was a bit disconcerting.
Now, Scott at Loki does state that petroleum based lubricants should not be used, and he lists proper lubricants that he recommends. I've always used white lithium grease in my reloads, but that was not on Scott's approved list. I did contact him via email asking if lithium was acceptable (before the flight), and he said it should be just fine. So I did lubricate with white lithium. This may be a factor?
Again, the burn and flight were just fine. But this is the first time I've seen an o-ring come out like this.
s6
On my recent L2 cert flight, I used a Loki 54/2800 stuffed with a K350 Moonburner reload. As per Loki standards, I used a silicone (orange) o-ring for the nozzle. The burn and flight all went great with no problems (and a successful L2!), however on cleanup I found something a bit odd. That silicone o-ring was sort-of melted a bit. It was still round, and still seemed to seal just fine, but it disintegrated upon removal and there was quite a lot of orange/white residue left in the slot that had to be scraped out. I've never seen this before other post-flight O-rings, and it was a bit disconcerting.
Now, Scott at Loki does state that petroleum based lubricants should not be used, and he lists proper lubricants that he recommends. I've always used white lithium grease in my reloads, but that was not on Scott's approved list. I did contact him via email asking if lithium was acceptable (before the flight), and he said it should be just fine. So I did lubricate with white lithium. This may be a factor?
Again, the burn and flight were just fine. But this is the first time I've seen an o-ring come out like this.
s6
donhuff
Well-Known Member
- Joined
- Dec 15, 2009
- Messages
- 289
- Reaction score
- 0
s6,
It's not to unusual for the nozzle o-ring to do that, especially with a moon burner, because of the long burn time the nozzle gets really hot and stays hot till long after the motor has shut down. Most of the time they are still hot when you retrieve the rocket and start breaking down the motor. I have seen some o-rings turn to dust after a burn. But the motor burn is so short, and the graphite conducts the heat slow enough, that it is not an issue during the burn. Regardless of the material the ring is made of.
BTW. I have found that silicone rings are of no benefit in our application, they don't hurt, but they don't do anything that a buna wont do.
It's not to unusual for the nozzle o-ring to do that, especially with a moon burner, because of the long burn time the nozzle gets really hot and stays hot till long after the motor has shut down. Most of the time they are still hot when you retrieve the rocket and start breaking down the motor. I have seen some o-rings turn to dust after a burn. But the motor burn is so short, and the graphite conducts the heat slow enough, that it is not an issue during the burn. Regardless of the material the ring is made of.
BTW. I have found that silicone rings are of no benefit in our application, they don't hurt, but they don't do anything that a buna wont do.
CarVac
Well-Known Member
- Joined
- Feb 12, 2012
- Messages
- 5,704
- Reaction score
- 37
I have had the same happen to me every time I have used snap ring motors with silicone o-rings on the nozzle, even with short burns.
I think they might be to prevent sticking to the graphite, which could otherwise ruin a good graphite nozzle. Because you can be sure that it will either be intact or turn to dust, you can be sure it will come out fine. I am always a bit afraid of scratching the graphite.
Binder Design
Well-Known Member
- Joined
- Jan 17, 2009
- Messages
- 1,823
- Reaction score
- 266
They are slightly easier to assemble with silicone rings.
Loki Research
Motor Manufacturer
- Joined
- Aug 20, 2011
- Messages
- 1,409
- Reaction score
- 596
Stealth6 said:
Nothing to worry about here. As Carlo said, the buna-n rings can stick to the nozzle. When they get really hot and have time to cool down, they can be extremely difficult to remove from the graphite without scraping it like crazy. I'm using silicone rings for just this purpose. When they get really hot, they turn to dust and are very easy to wipe off and clean from the nozzle. Even when they don't get that hot, they are still easy to remove. They actually have a bit higher heat resistance than buna-n too. If the motor is in a short case like the 38/120 & 240, I still use buna-n o-rings since the nozzles don't get that hot on those motors and easily removing them is not an issue.
Just like the high grade graphite and the convolute liners, the silicone nozzle o-rings are provided to make your experience with Loki Research motors that much better.
BTW, congratulations on you L2!
Hey s6,
I just purchased the same 54/2800 hardware from Scott, which coincidently arrived today, and it is intended for my L2 next summer. The K350 has that nice long burn, what rocket did you use and what was you AGL?
stealth6
insert witty tagline here
I don't want to derail this particular thread too much -
Kit-bashed Wildman 3" Darkstar, 11,761', and yeah it's a SWEET motor.
refer to this thread: https://www.rocketryforum.com/showthread.php?67596-s6-is-L2
s6
