OOA... Never Assume Reason

[Kharon]

Learnt about this the hard way as a new diver!! Now as an Instructor I teach the students on all courses to finish off their gear checks by closing the tank...look at the preasure gauge as they purge one of the regs....the needle should reach zero smoothly....if it stops you know it will also when you are diving. Time for a new one.

My SPG drops to zero pretty much instantly when I purge my reg. It's smooth but very quick. I'd have to be looking closely to see it twitch. And as fast as it drops, I bet it would blow over a minor stick. Not a real problem for me because my SPG is a backup for AI. I would notice pretty quickly if they didn't agree.

 

[caruso]

I read this thread and others just like it about spg failures, and I think about divers who say they can't trust an air integrated wireless wrist computer and I just shake my head.

 

[clownfishsydney]

I remember an Apollo gauge back in early 1990s which had a design fault. A small screw in the face used to come free and gradually work its way out and eventually stop the hand moving back towards zero. A very bad design fault.

 

[Landlocked123]

This is a great post. This now makes me re think the safety of the SPG. There seems to be a general feeling that SPG's are infallible. I honestly think to a degree I was probably on that band wagon before reading this. The thought of my OMS SPG failing me never crossed my mind. That said, during dives, I monitor air very closely and I usually know within 200 PSI or so how much air I have before I even reach for the SPG. My dives are very similiar in profile and duration so its amost like clock work. I think I would catch a faulty SPG in the sens that the reading would make no sense to me but still this puts perspective on the "assumptions" that we all make when we go diving.