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Difficulty putting on 8 inch flange and 2 o-rings

Hi everyone!

I am trying to put on the 8-inch flange & two o-rings on an acrylic tube without damaging the penetrators at the top. I have successfully put on a flange with a flat acrylic cover, but I had to turn the tube such that the acrylic plate is on the table. If I do the same thing with the penetrators, it might bend the sea-view connector I have. I was able to put one o-ring, it’s just the second one that’s difficult.

Any ideas on how to put on the flange? Also how difficult is it supposed to be to put on the second o-ring? I didn’t buy it off from BlueRobotics, but I bought it from I think their supplier, ePlastics. When I put it in, it is not as easy as how it is demonstrated in this assembly tutorial video Blue Robotics Tutorial: Assembling the Watertight Enclosure - YouTube

I’ve tried checking out this forum post, and originally I would push the tube off-axis to get the flange to go in O-ring Flange Installation

Do you have the end cap vented? If not, good luck putting it on. The canister will act like an air shock absorber.

Again, if you have NO open plugs on the end of the cap, pull one of the penetrators or whatever I see in the photo out so the air can escape.

Hi @thorag, welcome to the forum :slight_smile:

I agree with @hscadden that if you don’t have any open vent plugs/can’t open the other side of the tube this is likely to be really difficult because of the air pressure. Purely on the ‘might bend the sea-view connector’ front though, could you have it partly off the table, so you’re just pressing on the plate itself, or at most on the red penetrator blanks?

Are you talking about getting the o-ring onto the flange, or getting the flange into the tube? If you can get one o-ring onto the flange then you should also be able to get the other one on, since they should be the same diameter and thickness. I’d recommend sliding the first one on, then using one or two o-ring picks to pull it into the furthest in slot, and then slide on the second one into the closer slot.

Hi Harold, thanks for responding! I have one vent penetrator for the end cap. When installing it I took off the vent cap and the air is able to come out of the tube. Still, it is very hard to put the flange with both o-rings.

Hi Eliot, thanks for the kind welcome :grinning_face_with_smiling_eyes:

I haven’t thought about putting the sea-view penetrator partly off of the table with the red penetrators on the table. I will be sure to try that!

When I said, “how difficult is it supposed to be to put on the second o-ring?” I should I said, “How difficult is it supposed to be to put the flange with both o-rings”. I was able to get both o-rings onto the flange using the o-ring tool. I was also able to put the flange partially in the tube, but only up to one o-ring. The o-ring closest to the endplate is the o-ring that is preventing me from putting the flange all the way into the tube. My problem is similar to this forum post, except I have a larger diameter flange and tube (O-ring Flange Installation).

Thanks, everyone for replying to my post! I’m pretty new to using blue robotics stuff, so I appreciate all of your support :slightly_smiling_face:

I was able to get the flange into the tube, with both o-rings, by using the hand vacuum to create inwards pressure. The inwards pressure helped me with pushing the flange completely into the tube.

Although, I am still wondering how difficult it is to put the 8-inch flange into the tube with both o-rings. Is it supposed to slide in as easily as this assembly demonstration video? https://youtu.be/G6PqEsKjxHM

Thanks again to everyone who responded!

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Good idea, glad you managed to get it in place.

Most likely it won’t be as easy as in the video, through a combination of much larger tube size (more friction), and tighter tolerances to intentionally make it less likely for leaks to occur (which I believe is the case for all our tubes since that video was made).

Thomas, are you lubricating the O-rings with anything? For our pressure vessel and connectors that we are hooking up with O-rings … we will clean and install them with a thin film of Dow Corning 4 Silicone grease. This stuff is like the Bible standard for O-rings that you are using with electrical connections because it is a dielectric grease besides lubricating / filling in voids in the surface of the rubber.

I assume you are using recommended O-rings and the correct size too? The durometer can make things a pain in the rear too. If you are not using the recommended variants as defined by Blue Robotics you could run into some issues. Harder O-rings won’t compress as well and there is a laundry list of other issues too.