Apeks FSR first stage, when did they update it?

[lexvil]

I also asked the question to Aqualung about the reasoning for not recommending the fifth port on the older model, just got an answer back.
The reasoning (according to the guy who got back to me) was that it could be an issue if the hole got blocked in some way, since there is only one.
To me, that doesn't sound like the issue is with the flow, rather that the issue could present itself if you don't take care of your reg and make sure it stays clean on the inside.
Wrong or right?

I’m not well versed in this regulator but how would the fifth port effect this? If the hole is subject to fouling how would that effect functioning without the port as opposed to with the port?

 

[Degenerate]

I’m not well versed in this regulator but how would the fifth port effect this? If the hole is subject to fouling how would that effect functioning without the port as opposed to with the port?

I'm probably even less versed than you are which is why I asked if my reasoning was wrong.
I'm guessing Simon will shine some light on the matter.

 

[buddhasummer]

I’m not well versed in this regulator but how would the fifth port effect this? If the hole is subject to fouling how would that effect functioning without the port as opposed to with the port?

I'd assume it would affect the balancing but I can't see how that would shut off air flow, where I guess it "could" potentially shut off airflow to the 5th port (?) which is a bigger problem. Chances of that actually happening? I'd say pretty slim to nil.

 

[lexvil]

I'd assume it would affect the balancing but I can't see how that would shut off air flow, where I guess it "could" potentially shut off airflow to the 5th port (?) which is a bigger problem. Chances of that actually happening? I'd say pretty slim to nil.

So just to be clear on function, the fifth port is added to the end where the balancing air serves to assist the closing of the HP air? So if you are breathing from this hose you would be bleeding off balancing air?

 

[buddhasummer]

So just to be clear on function, the fifth port is added to the end where the balancing air serves to assist the closing of the HP air? So if you are breathing from this hose you would be bleeding off balancing air?

Yes, I believe so.

Experts:

@couv
@halocline
@rsingler
@herman

Any others feel free to chime in, this is way out of my area of knowledge.

 

[lexvil]

Yes, I believe so.

I can see the concern, this could do some weird stuff on balancing, reasoning is it won’t decrease breathing air but will possibly cause a spike in IP, not sure if it would be excessive but it seems they weren’t happy with it.

 

[buddhasummer]

I can see the concern, this could do some weird stuff on balancing, reasoning is it won’t decrease breathing air but will possibly cause a spike in IP, not sure if it would be excessive but it seems they weren’t happy with it.

They are pretty categorical about it not being done, so I'd certainly not do it.

 

[lexvil]

They are pretty categorical about it not being done, so I'd certainly not do it.

It would probably make the ip look like a piston reg’s, it would drive you crazy.

 

[admikar]

I’m not well versed in this regulator but how would the fifth port effect this? If the hole is subject to fouling how would that effect functioning without the port as opposed to with the port?

So just to be clear on function, the fifth port is added to the end where the balancing air serves to assist the closing of the HP air? So if you are breathing from this hose you would be bleeding off balancing air?

You're bleeding balancing air anyway. If you look at pictures that @buddhasummer posted, you can see that MP exit ports are right beside balancing ports. If that hole on old model gets blocked, without fifth port you loose balancing, but air is still going to second stage. With fifth port, that hole is sole connection to fifth port.
Edited to add: re why DST had a fifth port option far longer than FST/FSR: due to its construction, MP ports are on the other side of first stage body, balancing side. Therefore it was prudent to put more than one connection between both chambers. Therefore, DST already had redundancy for breathing fifth port.

 

[Centrals]

Why took Apeks so long to realize that the 5th port is a good idea for their flagship?
BTW, FST came before FSR.