New Shearwater AI transmitter - the Swift

[tursiops]

the plug blew out a caused an air leak. Thankfully this occurred after the dive was over or I would have had a bad air leak.

vs

my dive partner did notice a small trickle of bubbles coming from the vent hole but not a major air loss by any means.

You could completely unscrew the SWIFT from your first stage underwater and it would still take like 20 minutes for an AL80 to drain. The HP ports have flow limiters (tiny exit holes).

 

[Belzelbub]

I just had my Swift fail in a dive, it read 5000 psi on the start of the dive then didn’t connect until the end of the dive.

Was 5000 psi what you were expecting? Sounds very high to me. I would say it failed right at the start, which is when I would expect a non battery related failure to occur.

Unfortunately the issue is at the bottom of the the swift is a black plug, the plug blew out a caused an air leak.

It’s not a plug, it’s an over pressure relief valve. Similar to a burst disk on a tank. This didn’t blow and cause an air leak, it blew because there was an air leak. There should not be any pressure behind this valve. If there is, that’s a problem. Rather than allowing the pressure to build until the housing shatters, the pressure is released by that ”plug.”

 

[stuartv]

Was 5000 psi what you were expecting? Sounds very high to me. I would say it failed right at the start, which is when I would expect a non battery related failure to occur.

It’s not a plug, it’s an over pressure relief valve. Similar to a burst disk on a tank. This didn’t blow and cause an air leak, it blew because there was an air leak. There should not be any pressure behind this valve. If there is, that’s a problem. Rather than allowing the pressure to build until the housing shatters, the pressure is released by that ”plug.”

Ummm, what good is an OPV if there is no pressure behind it for it to relieve?

I believe, if it's an OPV, it should normally have tank pressure behind it. I.e. if it's on a full AL80, it should have 3000 psi behind it. Just like a burst disk on a tank - which also has full tank pressure behind it. That IS the point, after all. If the tank pressure gets too high, the burst disk (or OPV) releases the pressure in a more safe, contained way than if the too-high pressure causes the tank itself to rupture.

This all sounds like Shearwater has/had a bad batch of OPVs.

 

[Belzelbub]

Ummm, what good is an OPV if there is no pressure behind it for it to relieve?

I believe, if it's an OPV, it should normally have tank pressure behind it. I.e. if it's on a full AL80, it should have 3000 psi behind it. Just like a burst disk on a tank - which also has full tank pressure behind it.

I don’t believe that’s how it works in this case. The sensor is positioned at the inlet. In a transmitter, the only thing required to see tank pressure is the pressure sensor. The rest of the electronics does not need this pressure. The purpose of the housing o-ring(s) is to keep the electronics dry, not keep pressure in. The housing would need to be beefed up to hold back tank pressure.

This all sounds like Shearwater has/had a bad batch of OPVs.

Possible, or perhaps the OPVs are working fine, there is just a bad seal around the pressure sensor.

 

[jrouss28]

Was 5000 psi what you were expecting? Sounds very high to me. I would say it failed right at the start, which is when I would expect a non battery related failure to occur.

It’s not a plug, it’s an over pressure relief valve. Similar to a burst disk on a tank. This didn’t blow and cause an air leak, it blew because there was an air leak. There should not be any pressure behind this valve. If there is, that’s a problem. Rather than allowing the pressure to build until the housing shatters, the pressure is released by that ”plug.”

No the tank should have was around 3000, I had an SPG as well. When I contacted Shearwater, they replaced it. My understanding is that there may have was a batch that had problems with an O ring. Don't quote me on that though, this was quite a while back now.