Swap Apeks DS Vent Valve for SiTech

[73diver]

I was disappointed in having what I considered “an excessive bubble” in my drysuit when I ascended. This sometimes made it difficult to stop at 15’ or 20’. The SiTech vent valve has received lots of praise. So, I decided to replace the original Apeks with a SiTech.

I fabricated a tool to help remove the Apeks. The SiTech is not an exact replacement: The Apeks valve diameter is ¼” smaller than theSiTech.

With the smaller diameter of the SiTech, it seemed counterintuitive that flow would be higher than the Apeks. I used a crude water manometer to measure the required pressure differential to cause venting of both valves. As near as I was able to measure both valves opened at about 0.4-0.5” H2O. I could not measure flow rate. I set both valves 4 clicks closed. There was a significant difference. The SiTech vented at around 2” H2O. The Apeks vented at around 8” H2O.

I masked the area around the grommet in the suit. I used clear RTV silicone as a sealant. I thought the white marine silicone might be too difficult to remove if I wanted to undo my work.

I filled the space between the threads and the raised ‘bead’ with RTV silicone to a height that approximated the height of the bead. I tried to keep the RTV silicone away from the threads.

The pieces were assembled on the suit. The RTV silicone was allowed to cure for 24 hours.

I have made about 40 dives with the new SiTech vent valve. The improvement with the SiTech was noticeable. Upon ascent, venting the expanding bubble was a easier and controllable. I watched the venting using a small plastic mirror bungied to my left wrist or the face of the dive computer. The vent rate of the SiTech appeared similar to the Apeks but it didn’t seem to be as difficult to vent the bubble accumulating in the left arm.

I am happy with the result.

 

[EstaDive]

What kind of Apeks exhaust valve were you using? My understanding is that there are three kinds commonly out there:

• Old low profile
• New low profile
• High profile

I ask because there are some older posts on the forum that discuss the problems with the old apeks valve and seem to suggest that the newer low profile valves are comparable to si-tech.

 

[73diver]

I don’t know which type of Apeks low profile valve I replaced. It was originally purchased in 2014. As I indicated, using measurements both valves appeared similar except in how many clicks of clockwise rotation were required to obtain a given vent pressure. While diving I notice a slightly easier venting process with the SiTech.

 

[EstaDive]

Thanks. I'm not sure when they switched over, looking at discussions it seems like around 2010, but it's not entirely clear since it seems that there were some minor changes to the old apeks valves to handle the leaking before they switched over to a completely new design. I found some more details of the different valves here:
http://www.swiss-cave-diving.ch/PDF-dateien/DUI_Drysuit-Dump-Valves.pdf
and discussion: It's that time again, Dump Valves...

I ask because I have a suit with the old apeks valve, and have run into similar issues. I thought just replacing with a new Apeks would solve the problem. However, it sounds like maybe the new apeks valves are still inferior to si-tech.

 

[Doby45]

I don’t know which type of Apeks low profile valve I replaced. It was originally purchased in 2014. As I indicated, using measurements both valves appeared similar except in how many clicks of clockwise rotation were required to obtain a given vent pressure. While diving I notice a slightly easier venting process with the SiTech.

I will give you $20 for the old crappy Apeks if you can send me a pic..