Question Question on how to attach an extension hose between an MK17 and a Suunto pod

[tggm]

Hey there,

I have newbie questions about high pressure stuff

I bought an extension hose from TDS together with a Suunto pod. The idea is (of course) to get some distance between the transmitter and the first stage.

Without the hose things assemble OK, however with the hose the o-ring on the pod doesn't "sit right" on the hose exit's side.

Some pictures to make this clear.

1) this is the setup without the hose. On the left is an adapter that comes with the Mk17Evo first stage and in the middle the airflow restrictor (Type A) that comes with the pod. This appears to be OK. No more parts necessary.

2) This is the setup with the hose and the type B restrictor.

The problem with setup 2) is that the o-ring bulges out. The more I tighten the more it slips out

Also, a close-up of the hose's exit side. The exterior nut is free to move up and down.

What should I do in this situation? Is the hose extension not appropriate for this case?

I could also use the SP adapter on the pod side but I'm unsure if the pressure restrictor will be properly isolated (it has to be type A which does not have an o-ring on the hose side).

Or should I just stop messing around and pay the store to assemble this for me?

Thank you!

 

[Belzelbub]

I don't use an extension on my transmitter.

How I understand it, the O-ring on the transmitter forms the seal against the 1st stage when attaching directly. When using an extension hose, the O-rings on the spool form the seal. Looking at the shape of the hose connector on that end, it's not relying on an O-ring at that point. Try taking that O-ring off and test to make sure it seals.

 

[tggm]

I don't use an extension on my transmitter.

How I understand it, the O-ring on the transmitter forms the seal against the 1st stage when attaching directly. When using an extension hose, the O-rings on the spool form the seal. Looking at the shape of the hose connector on that end, it's not relying on an O-ring at that point. Try taking that O-ring off and test to make sure it seals.

You're right. I removed the o-ring and (using the spool) it seals fine.

Thanks!

 

[scubadada]

Why do the Suunto transmitters have a flow restrictor? Why are they not manufactured like that in the first place? Sorry, I have only used PPS MH8A transmitters.

 

[tggm]

Why do the Suunto transmitters have a flow restrictor? Why are they not manufactured like that in the first place? Sorry, I have only used PPS MH8A transmitters.

I'm not sure. My Mk17 first stage already has need pin sizes holes on the HP ports. I noticed that my scubapro pressure gauge also has a (almost microscopic) pin sized hole on the hose.

It may be the case that HP equipment manufacturers don't want to assume that flow restrictors are present upstream (in the first stage ports) so they provide their own.

Nevertheless with the extension hose a spool is always necessary and (as far as I know) a spool is also a flow restrictor.

 

[tggm]

Another update on this:

I had to replace the transmitter (battery issue) and when disassembling I noticed that the outside of the spool was wet. Also the inside of the transmitter's canal had a small drop of water.

I'm not sure is this is good. I know that it doesn't leak air out, but what about water getting in? I'm worried that the nut on the hose does not cover the external o-ring that comes with the transmitter (I ended up removing that o-ring since the nut would crush it).

Please note that I don't think there's any mix between the air part and the outside environment. What worries me is that water is getting so near the spool:

Should I find an hose with a proper nut that "covers" the o-ring to make a perfect seal? ie, the part in red on the picture below should be wider and allow the o-ring to sit inside?

Anyone know what type of nuts /sizes are standard for HP-hoses?

Thanks for any help!

 

[Belzelbub]

The green in your drawing are the o-rings on the spool, right? If so, they appear to be doing their job. Water on the other side of the o-rings would mean they aren't sealing well for some reason, and should be replaced (o-rings or spool).

If diving in salt, a good soak, and some agitation, in fresh water would be good to keep salt crystals out.

 

[tursiops]

My understanding is there are two different spools, one for mounting the transmitter to the first stage, one for use with a hose.

Pictures of how to mount a transmitter using a short hose ...

I keep 3 until I've used them then replace the orings

scubaboard.com

 

[Scared Silly]

The green in your drawing are the o-rings on the spool, right? If so, they appear to be doing their job. Water on the other side of the o-rings would mean they aren't sealing well for some reason, and should be replaced (o-rings or spool).

If diving in salt, a good soak, and some agitation, in fresh water would be good to keep salt crystals out.

Spot on. FWIW, regardless if one is using a transmitter or and SPG this connection is the most neglected connection. The water that gets trapped in there is typically salt water. Which over time will corrode the spool. With enough corrosion the spool will break. At that point one will see small bubbles.

 

[tggm]

My understanding is there are two different spools, one for mounting the transmitter to the first stage, one for use with a hose.

Pictures of how to mount a transmitter using a short hose ...

I keep 3 until I've used them then replace the orings

scubaboard.com

Yes. I'm using the proper spool for this.

Spot on. FWIW, regardless if one is using a transmitter or and SPG this connection is the most neglected connection. The water that gets trapped in there is typically salt water. Which over time will corrode the spool. With enough corrosion the spool will break. At that point one will see small bubbles.

So, it's expected that water gets in anyway (on the outside of the spool) ?