View Full Version : how tight do compression
spaz77
02-28-2009, 01:21 AM
fitting have to be in order to have a good seal? should there be a gap between the bottom part of the fitting and the thread? or screwed all the way down ?
SoulsCollective
02-28-2009, 01:36 AM
Compressions should be hand tightened until you feel them bite. What this works out to in terms of gaps will depend on the fitting. Don't use pliers, ring-grips or any tools, tighten them too much and you can cut into the tubing.
spaz77
02-28-2009, 01:43 AM
Compressions should be hand tightened until you feel them bite. What this works out to in terms of gaps will depend on the fitting. Don't use pliers, ring-grips or any tools, tighten them too much and you can cut into the tubing.
So get them a quarter turn past snug and I should be fine?!
Jhors2
02-28-2009, 01:43 AM
Kinda on this topic, but I was curious if any of you guys use teflon tape on the fittings when screwing them into blocks/rads etc??
spaz77
02-28-2009, 01:46 AM
Kinda on this topic, but I was curious if any of you guys use teflon tape on the fittings when screwing them into blocks/rads etc??
I am sure none of us do, although I cannot speak for most, but that what the oring is for if you are worried about leaks!
Metric
02-28-2009, 01:48 AM
Kinda on this topic, but I was curious if any of you guys use teflon tape on the fittings when screwing them into blocks/rads etc??
Basically all of the fittings today use parallel threading (BSPP), so there's no need for teflon tape, which is mostly used on tapered threads (BSPT). http://en.wikipedia.org/wiki/ISO_228
Jhors2
02-28-2009, 01:48 AM
Thanks Spaz, and thanks Metric for the link! I didnt mean to derail your thread at all.
spaz77
02-28-2009, 01:49 AM
Thanks Spaz, and thanks Metric for the link! I didnt mean to derail your thread at all.
NO worries man, I am just here to learn as you are also
fallwind
02-28-2009, 01:56 AM
I tightened my compression fittings all the way down to as far as they can go. Takes some work but they do go that far, atleast with Primoflex. Might be tougher with harder tubing.
spaz77
02-28-2009, 02:02 AM
I use the feser 3/8 1/2OD and I can get all the way down with some force, I just don't think I should have to use that much force to secure the tubing :shrug:
SoulsCollective
02-28-2009, 02:25 AM
I tightened my compression fittings all the way down to as far as they can go. Takes some work but they do go that far...
I can get all the way down with some force, I just don't think I should have to use that much force to secure the tubing :shrug:
You shouldn't and you don't. Remember, people - these are not load-bearing joints, compression fittings are designed to give you a secure seal with merely the force required to hand tighten them. . Tighten down too far and you physically damage the tubing; the edge of the compression will cut into the tubing, increasing the chances of a leak.
spaz77
02-28-2009, 02:29 AM
You shouldn't and you don't. Remember, people - these are not load-bearing joints, compression fittings are designed to give you a secure seal with merely the force required to hand tighten them. . Tighten down too far and you physically damage the tubing; the edge of the compression will cut into the tubing, increasing the chances of a leak.
Thanks for the help man, off topice but how are people mounting the ek multi res are they using screws or just 3m tape?
Thanks for the help man, off topice but how are people mounting the ek multi res are they using screws or just 3m tape?
go to your local hardware store and ask for industrial velcro, ive stuck some obscenely large things together for years with this stuff, much heavier than a full ek res and it hasnt dropped, infact i cant even pull the two parts away from each other! and the backing is stickier than a pedos pants in a playground.
Good to know. I assumed you would want to completely tighten the comp.fitting around the tubing.
SNiiPE_DoGG
02-28-2009, 10:58 AM
Kinda on this topic, but I was curious if any of you guys use teflon tape on the fittings when screwing them into blocks/rads etc??
teflon tape is for tapered thread fittings used in plumbing. NEVER use in on the parallel threads of G1/4" it will only result in problems. The O-ring on the fitting is more than adequate to seal the thread.
Hondacity
02-28-2009, 10:58 AM
tighten them all the way down...
i've done it one lots of 1/2-3/4 tubes ....and no damage whatsoever
D-Cyph3r
02-28-2009, 12:47 PM
Haha. So much conflicting info here.
I got some 1/2" ID 3/4" OD comps with XSPC tubing and decided to see how far down they'd go if I put some muscle into it. Of course they did go all the way down, and tugging on the tubing didn't result in it popping off, but after unscrewing it the tubing was cut slightly.... if it was left in a loop for any period of time theres every chance it could have split enough make the fitting pointless.
I'm in the the "dont" tighten them all the way down camp.
Spankyfart
02-28-2009, 01:48 PM
Kinda on this topic, but I was curious if any of you guys use teflon tape on the fittings when screwing them into blocks/rads etc??
Only use teflon on metal/metal barbs with no O-ring.
On topic: Hand tighten them down, and give them a small twist (less then 45 degrees) with pliers.
Never failed me.
saxile
02-28-2009, 02:14 PM
Now something else that does effect the amount they tighten down is the tubing itself, stiff/hard tubing doesn't go as far, while limp/soft tubing can go all the way. Another thing is how clean and straight the cut of the tubing is can effect the distance.
zlojack
02-28-2009, 02:26 PM
I try to tighten mine all the way. Most are there or 90% there. No leaks here.
drak3
02-28-2009, 02:27 PM
On mine there is a small gap after tighten them by hand and a final turn using a kitchen towel for grip (no tool). When I did the final turn it felt like the tubing perfectly sealed as I felt some sort of bounce (rubber got compressed I assume). No leaks so I guess is fine ...
Waterlogged
03-02-2009, 11:44 AM
This might explain why you don't want to over tighten the nut on a comp fitting.
Don't mourn this fitting. The thread on it is 12mm which is useless on 99% of all cooling gear.
http://www.xtremesystems.org/forums/attachment.php?attachmentid=83762&d=1218962250
zlojack
03-02-2009, 11:47 AM
But WL, what defines "overtighten"? There's only so far they can go.
SNiiPE_DoGG
03-02-2009, 11:49 AM
But WL, what defines "overtighten"? There's only so far they can go.
I think if it was possible to do this with reasonable force the pressure at the choke point at the top of the barb, if great enough, would sever the tube...
Waterlogged
03-02-2009, 11:51 AM
But WL, what defines "overtighten"? There's only so far they can go.
Using anything more than finger strength is over tightening (ex. I've got Alphacool comps that have nut flats on the top of them and only use my fingers to tighten them).
You may have fittings and tubing that match up nominally size wise....doesn't mean the tube is actually the exact sizes stated, there is some give and take there. ;)
zlojack
03-02-2009, 11:55 AM
I realize that. But my "finger strength" isn't the same as someone else's.
If one person gets them all the way down, while the other gets them down only so far with a 2 or 3mm gap, how are we to know the risk there?
I mean, there is room for the tubing to be compressed by the top piece, as that's the concept of the barb. I'm wondering if bottoming out the barb really would cut the tubing as it's supposedly designed that way. I do understand the point you're trying to make about the "choke point" at the top of the barb, Snipe, but isn't it supposed to be tight up there in order to form a seal?
SNiiPE_DoGG
03-02-2009, 12:09 PM
I realize that. But my "finger strength" isn't the same as someone else's.
If one person gets them all the way down, while the other gets them down only so far with a 2 or 3mm gap, how are we to know the risk there?
I mean, there is room for the tubing to be compressed by the top piece, as that's the concept of the barb. I'm wondering if bottoming out the barb really would cut the tubing as it's supposedly designed that way. I do understand the point you're trying to make about the "choke point" at the top of the barb, Snipe, but isn't it supposed to be tight up there in order to form a seal?
well on BP barbs the tube is sealed by going onto the metal nub, and the cover/nut that goes over it is a locking mechanism that secure the tube from coming off of the seal.
soulesschild
03-02-2009, 12:15 PM
Remember, I over tighetend my fittings the first time I was organizing my LCS and later realized I could shorten some tubing and boy did I have a hard ass time getting them lose again.
zlojack
03-02-2009, 12:15 PM
True enough.
Well, I just crank them as far as they go by hand pressure, which is usually all the way.
If I cut any tubing, I'll let you guys know.
Waterlogged
03-03-2009, 12:03 AM
I realize that. But my "finger strength" isn't the same as someone else's.
If one person gets them all the way down, while the other gets them down only so far with a 2 or 3mm gap, how are we to know the risk there?
I mean, there is room for the tubing to be compressed by the top piece, as that's the concept of the barb. I'm wondering if bottoming out the barb really would cut the tubing as it's supposedly designed that way. I do understand the point you're trying to make about the "choke point" at the top of the barb, Snipe, but isn't it supposed to be tight up there in order to form a seal?
Well, the thing is, there are tolerances on tubing just like everything else. It's pretty easy to control tolerances on something hard like the fittings but it gets a bit tougher on some soft like the tubing. Lets say you got fittings that are on what machinists call "the high side" of the tolerance (meaning slightly bigger than "nominal"), when you add plating to that, it'll get even bigger, now if you throw in tubing that's on "the high side", you could be looking at a comp nut that only goes down 1/2-3/4 of the way with finger pressure. If you try to force it, you may damage it. Now if the fittings are "nominal" or "the low side", that same tubing might allow the nut to go all the way on with no problems at all. This is why I recommend finger tight, anything else may be asking for unwanted trouble down the road.
DeathWalking
03-03-2009, 03:46 AM
I think what he's saying is that there are varying levels of finger-tight. I'm currently installing some BP compressions myself, and I'm only finger-tightening them, but with a lot of force I'm getting them to 15/16th of the way tightened. I'm sure this is not what you mean by finger tight :p