HELP - Lifegard Aquatics Promax 3"

[willworkforfish]

Hello all,
I'm investigating an o-ring sealing issue that i encountered on my promax 3". It appears lifegard redesigned the 3" housing caps around 2019. The old revision that I have cant seal on the red o-ring and relies entirely on the flat black gasket, which leaked on me. In an attempt to resolve my leaking issue, I purchased a new housing cap and o-ring set from them which I suspect is not backwards compatible with my housing (the red o-ring doesnt come close to making contact with its sealing surface on the housing). Lifegard has not been helpful in identifying the cause and solution to my problem other than suggesting that I buy new housings and caps for almost the same price as the original unit. I am looking for images of the newer housing flange revision to understand if the newest design resolved the o-ring issue on my older version, and if it is backwards compatible.

If anyone has 3" promax of any wattage purchased after 2019, I would greatly appreciate a picture showing the housing flange sealing surfaces. A caliper measurement of the sealing surfaces of the housing flange ID would be even better. I have identified aftermarket o-rings that will resolve this issue for anyone else that experiences leaks on these older units, but I would also like to understand if the design issue has been resolved on the newer units. I appreciate any time you may have to help.

 

[exnisstech]

I have one here and a set of calipers if you can show me exactly what measurements your looking for

 

[willworkforfish]

Thank you!!! It would require taking the four bolts off to access the housing flange. I'm not sure what your flange looks like but it would be nice to know the inside diameter of all of the surfaces, particularly the largest diameter (shown in my pic). It would also be helpful to see a picture of your housing flange to understand the design. Thanks again

 

[willworkforfish]

The way my unit was configured, the red oring show is expected to be super stretched to seal on the housing, but its almost impossible to do because the flange steps are so small and the oring falls off... I hope you dont have my version, and if you do... I'll help somehow. In the picture below, you can see how there are a bunch of small steps for the oring to sit on, none of these result in compression of the oring and the largest one is sooooo hard to get the oring onto because of the short height of the step.

 

[exnisstech]

Gotcha. It's pouring rain right now. Once it let's up I'll head out to the shop where my tools are and get measurements for you.

 

[A_Blind_Reefer]

Call up marineandreef.com @MarineandReef Jaron

I had an oring kit come in that was labeled as the correct part number, but was a much smaller oring for a different model. There was some mixup at Lifegard. M&R went through their stock for me and found the right orings. They are awesome!

It sounds like you are going through the same thing. Mine is a 3” pro max as well.

 

[exnisstech]

Hope these help. It's still apart if you need any other measurements

 

[willworkforfish]

Call up marineandreef.com @MarineandReef Jaron

I had an oring kit come in that was labeled as the correct part number, but was a much smaller oring for a different model. There was some mixup at Lifegard. M&R went through their stock for me and found the right orings. They are awesome!

It sounds like you are going through the same thing. Mine is a 3” pro max as well.

Thanks for the info but the new set of orings i purchased are the same size as the original ones that came on my unit. They are only ~0.100" cross section, which is much smaller than the 5" promax appears to have...however, i think i have the "correct" o-rings (i got the new ones directly from lifegard).

 

[A_Blind_Reefer]

Thanks for the info but the new set of orings i purchased are the same size as the original ones that came on my unit. They are only ~0.100" cross section, which is much smaller than the 5" promax appears to have...however, i think i have the "correct" o-rings (i got the new ones directly from lifegard).

Gotcha. The orings I got were Lifegard as well. Same size as the original but about half as thick. The mixup was at Lifegard. The stock they sent out was labeled right, but the wrong size. Luckily m&r had plenty of stock and went through them and found some of the right ones in the right bag. Even if you didn’t buy it from them they’ll help you out. They know those units well. I can’t see to look at your pics but it certainly sounds familiar. The only thing I think they changed was the end cap for the quartz sleeve. The newer model allows you to replace the bulb without breaking the seal. That part fits the older models, I did it. So I think everything is backward compatible.

 

[willworkforfish]

Hope these help. It's still apart if you need any other measurements

Oh man, thank you so much for taking the time. Those dimensions and design appear to be the same as mine. I suspect we both have the old (pre 2019) version. I'd suggest you clean off the black gasket and its sealing surfaces before you reassemble. I'm not convinced that the red o-ring does anything on our version.

To clarify my concerns with the red o-ring on the pre 2019 model:
- The ID of the sealing surface on the housing flange is 89.3mm
- The OD of the housing cap is 84.6mm
- The red O-ring cross section is 2.5mm

After installing the OD on the housing cap, the resulting OD of the o-ring is at most ~89.6mm
since stretching the oring this much will reduce its effective cross section. (Flange OD + 2xO-ring CS)

This means that the maximum radial compression the o-ring could ever see is 0.15mm [0.006]. This is the bare minimum compression that is recommended for o-rings to prevent compression set. Its probably just enough to make a functional seal, but since the housing features don't tightly hold the o-ring concentric, you could lose the seal if assembling it slightly out of alignment. This design probably relies on pressure to create the seal. When i measured the resulting o-ring OD on mine, if found that it is even less than the housing ID (granted that it is hard to measure compressible diameters).

Also, if you look closely at the edges of the housing sealing surface you'll notice there is no lead in chamfer to guide the o-ring into its seat (on the pre 2019 versions). The absence of this chamfer prevents the design from using an appreciably thicker o-ring (to get more compression) because it would bind on the sharp edge during assembly. I suspect this was the issue that triggered Lifegard to revise the design in 2019. I'm still hoping to find a view of the new design to understand if they resolved this.

But for now, I have two different versions of the housing cap and nether of them seal on the housing that I have unless I use custom o-rings for each of the two designs. My interactions with Lifegard have been underwhelming. They are quite responsive but have avoided providing any sort of technical information or acknowledging differences in design so I can confirm which parts I've needed. I had originally been hoping that they somehow gave me the wrong o-ring the first time, but that does not appear to be the case.

If anyone reading this has a new model (purchased after 2021), I would appreciate a picture and measurements so I can be confident in the o-ring recommendations I make (coming soon). I'm also curious if the new design corrected the issue and increased minimum compression of the o-ring.

 

[exnisstech]

Oh man, thank you so much for taking the time. Those dimensions and design appear to be the same as mine. I suspect we both have the old (pre 2019) version. I'd suggest you clean off the black gasket and its sealing surfaces before you reassemble. I'm not convinced that the red o-ring does anything on our version.

Sorry I wasn't sure how old mine was. Mine does not have a gasket tho. The oring is the only seal on it. It's never been disassembled but I pulled the other end just to make sure I didn't loose the gasket and it just has the oring, no gasket.

 

[willworkforfish]

Gotcha. The orings I got were Lifegard as well. Same size as the original but about half as thick. The mixup was at Lifegard. The stock they sent out was labeled right, but the wrong size. Luckily m&r had plenty of stock and went through them and found some of the right ones in the right bag. Even if you didn’t buy it from them they’ll help you out. They know those units well. I can’t see to look at your pics but it certainly sounds familiar. The only thing I think they changed was the end cap for the quartz sleeve. The newer model allows you to replace the bulb without breaking the seal. That part fits the older models, I did it. So I think everything is backward compatible.

I can say with relative certainty that the housing caps are not backwards compatible with the housings. The outside diameters are different and the stepped features do not exist on the new cap design, so the o-ring will not be forced far enough into the housing to create a seal, unless you add a spacer or stack o-rings. The interchangeability you're talking about with the quartz sleeve is correct, i dont see any interchangeability issues there. I attached a picture showing the differences between the two housing cap versions.

 

[willworkforfish]

Sorry I wasn't sure how old mine was. Mine does not have a gasket tho. The oring is the only seal on it. It's never been disassembled but I pulled the other end just to make sure I didn't loose the gasket and it just has the oring, no gasket.

All good man, I appreciate your info and it was nice to see that your housing measurements were consistent with mine (they were basically identical). The black gasket gets really smooshed in there and looks almost identical to the plastic. I'm pretty certain that i can see it in your pictures at the bottom of your housing.

 

[A_Blind_Reefer]

Got it. I found the pics I sent in when I had a problem. Overall size was the same, cross section was off. They would fit but barely make contact. Best I could explain it was that the originals were about the same thickness as the super bright orange 2” endcap orings. Mine also has the black flat gaskets. Still think that if Lifegard isn’t helping you out that m&r is a great resource. Don’t know why you’re apprehensive about contacting them though.

Edit.correct oring was .120” thick whereas the wrong one was .1” thick (approx as I can’t see and used a digital caliper than had my phone read the measurement to me)

 

[exnisstech]

All good man, I appreciate your info and it was nice to see that your housing measurements were consistent with mine (they were basically identical). The black gasket gets really smooshed in there and looks almost identical to the plastic. I'm pretty certain that i can see it in your pictures at the bottom of your housing.

Aha I found it. Old guy eye sight lol. I agree I don't see the need for the oring with the gasket in there. Good luck getting what's needed. I'll follow this thread for your resolution. If the items aren't too expensive I'll purchase what's needed to reseal mine. I'm not planning on reinstalling it but new seals would be a good thing to have in case I do or to include if I sell it.