Is the eject force of a gas strut also a measure of how well it can resist..

[cjard]

..being yanked open?

I'm looking to fit a gas strut (possibly 2) to a glass door in the side of my house. It catches the wind if opened and if it blows against the reveal it'll get ruined. I'm not wanting an auto closer, as there are times I foresee wanting to leave it open too, so I figured a gas strut could work and assist in leaving it open as well as closed, but to be properly effective it'll need to damp in the opening direction. I'm aware that they do damp, as anyone who's tried to pull a hatchback door open faster than it wants to g, will attest...

But is the eject force (which I assume to mean "how hard it pushes when trying to open itself" also a fair measure of how much resistance it presents when the user(which in this case would be the wind) is pulling it to extend it faster than it wants to?

Alternatively I could look into an autocloser that can be locked off, but I do tend to find with commercial openers at least that they tend to offer little resistance to doors being opened..

 

[magicmushroom666]

I doubt the damping on gas struts is specified like that, they are mostly just about the opening force.
What about fitting something like this to restrict the door when its open, had these on a flat before and they worked very well to stop the door slamming.

 

[Belle427]

What kind of door construction is it ?
You can buy restrictors that attach to the top of certain doors. Ive fitted them to upvc style doors in the past.

 

[cjard]

It's an aluminium frame, entirely double glazed door 1m x 2.5m.. Probably weighs around 75kg

Note that I'm after stopping it from slamming open, rather than slamming closed, if that makes sense.. The ideal case would be a device that damps it on the opening direction, and then holds it open short of crashing into the reveal on the wall. This way it could be left opened in a breezy summer with no fear of damage, and if opened when a wind is blowing, it won't fly out, dragging the user with it and showering them in broken glass..

 

[Avocet]

Interesting project!

Couple of thoughts:

1. I've never seen a gas strut force labelled as "eject force", but I think it must be, as you suggest, the force at a particular temperature, which it exerts aganst anyone trying to compress it.

2. The forces are normally specified in newtons or "N". 10N would need (roughly) a force equivalent to a weight of of 1kg acting directly down on it, to overcome it. In reality, the initial force is likely to be more, because of stickiness in the initial movement. A 350N strut would need 35kg on it to move it.

3. It varies with temperature, somewhat. In the cold, it ill be slightly less, as the gas contracts.

4. The damping is normally done with a bit of oil inside the strut that is forced through some small internal restrictors. The oil is really there to lubricate the piston rod and seal. the damping is a sort of "freebie". For it to work properly, the thick end of the gas strut must be above the thin end (i.e. the piston rod). Otherwise:
(a) the oil runs to the other end of the strut (on most designs) and doesn't then pass through the restrictors and
(b) it doesn't lubricate the piston rod seal, so the life of the strut is reduced. This might be a problem if mounting it horizontally for this application.

5. I'm sure it is possible to have a bracket that allows the strut to go "over centre" so that it both holds the door closed or holds it open. However, unless the frame is pretty stiff, you might fidn that just having it acting on the top of the frame allows the door to flex too much if the wnd catches it, and then at the end of its strike, it could crack the glass as the top of the frame is brought to a sudden stop, whils tthe rest of it (and the mass of the glass) tries to carry on.

6. To experiment, you can buy "adjustable" gas strust that come filled to maximum pressure and have a little Allen grub screw in them which you just crack open to release some gas until you've got it how you want it. Unfortunately, you can only let gas out, so if you let too much out, it's scrap.

http://www.sgs-engineering.com/gsv6-100?gclid=CJbmqNadntACFQEM0wodIxUJnw

7. In general terms, the LOWER the pressure, the shorter the life of the strut because it uses the gas pressure to hold the seal against the piston rod.

8. I don't know if there are any where you can adjust the level (or distance) of damping at the end of the stroke.

 

[jj4091]

http://www.prnewswire.com/news-rele...aximum-control-and-convenience-566041091.html or https://www.google.co.uk/?gfe_rd=cr&ei=TmjWU-yjCOnH8gfZnoD4AQ#q=adjustable+door+opening+damper & click on images