Piston or diaphragm 1st stage ?

[Thomasbrown02tb]

Hi everyone, I've been on a couple of dives but quite new to diving and am trying to teach my self more detail about gear before purchasing my own (and also cause I just like learning about it ).

I was more inclined towards a piston first stage to be honest however a source stated that piston 1st stages recieve water through them whilst they are working underwater while diaphragm ones do not. I dive only in sea water and was wondering if the salt would damage the components in the piston reg, therefore is a diaphragm more suitable for me as a diver who dives only in sea water ?



Thanks in advance. And apologies if question is funny or anything like that but your suggestions would really help

 

[emoreira]

Rinsing is key after a dive day, no matter if the first stage is piston or diaphragm.
If you are diving extreme cold water, Diapragm is the way to go or an environmental sealed piston. But otherwise, it's the same.
Diaphragm first also receives direct water to sense ambient pressure or depth, though it goes no so "inside", however a complete and thoroughly rinse is mandatory, always. Make sure that the first stage dust cap is placed and secured. Move aside hose protectors (if installed) and let it dry extended.
How long should you rinse the reg, a lot, and after that, a lot more.
Remember not to press the purge button in the seconds when rinsing.
Take a close look to the dust cap. Some have an o-ring inside to seal the air port. If not installed, I do not recommend to submerge the first stage if it's not under tank pressure.

 

[tbone1004]

the majority of rental regulators out there are probably unsealed piston regulators because they're so cheap. If you are buying your own gear, I would strongly recommend sealed diaphragms because the risk of issues if you don't clean them off is pretty minimal. If I only dove in the salty stuff I wouldn't own anything but sealed diaphragms.

 

[Thomasbrown02tb]

the majority of rental regulators out there are probably unsealed piston regulators because they're so cheap. If you are buying your own gear, I would strongly recommend sealed diaphragms because the risk of issues if you don't clean them off is pretty minimal. If I only dove in the salty stuff I wouldn't own anything but sealed diaphragms.

Thank you !
During my training I was thought to let the hoses and 2nd stage sit in water for a while with the first stage out of the water container so I dont know how to clean a first stage yet.

So what do you think about a sealed piston sir ? Or would you still go for sealed diaphragm?

thanks

 

[shurite7]

The key factor is maintaining your gear properly and routinely. I own, dive, and service both types. If you don’t maintain the reg properly it has the potential to give problems, regardless whether it is piston or diaphragm.

 

[bakodiver391]

Another vote for sealed diaphragm. i service tons of regs and the piston ones always need more love more frequently. Performance is the same so why have salt water in the innards?

 

[maj2]

Another vote for diaphragm.
Although you plan on only sea water (presumably warm sea water), you never know what your future plans may entail. I know my current diving is nothing like what I imagined it would be right after O/W.
If you ever decide to get into cold water diving, I would go for something that can be called on to reliably do both.

 

[tbone1004]

Thank you !
During my training I was thought to let the hoses and 2nd stage sit in water for a while with the first stage out of the water container so I dont know how to clean a first stage yet.

So what do you think about a sealed piston sir ? Or would you still go for sealed diaphragm?

thanks

sealed pistons when sealed with grease a la Atomic are idiotic. Pain in the butt to clean for the techs, and expensive to pack because the cost of the grease is stupid. Scubapro engineered around it for cold water, Atomic couldn't be bothered. Remember also that these seals were done for cold water performance, not to keep them "clean", a sealed diaphragm is vastly superior for ease of maintenance.

 

[lexvil]

A point I took from your post is you are under the belief the sea water is in the internals of a piston regulator when its actually not the case, the water does go into an area exposed to the water, it’s important to the functioning of the regulator but it doesn’t enter into the air side. The extra maintenance of making sure all salt and other contaminants are rinsed from the ambient area of the regulator are what other are referring to.

piston regulators work great but I prefer the simplicity of a sealed diaphragm. I also find sealed pistons work great and can keep unwanted stuff out of the first stage making after dive rinsing much simpler and faster, while not necessary it is beneficial.

SP did well for freeze protection in the Mk25 but my main concern is contamination and premature wear.

 

[lowwall]

Let's look at where the water is. Here's an illustration of a standard piston first stage. The blue (cyan) is the water you are diving in. It comes in via little holes in that section of the reg.

Not shown is the o-ring that the piston passes through in the grey section between the spring section and the high pressure section. You can see that the main spring and much of the piston are submerged in water, the walls of the ambient pressure section are wet, and the o-rings have water on one side. Accelerated wear is possible on all of these surfaces, especially if the reg is not thoroughly rinsed between dives. It's also possible for ice to form inside the reg or grit to damage an o-ring, resulting in wet breathing, leaks or a freeflow.

Here's a standard diaphragm reg:

Here only the main spring is submerged. The diaphragm seals off all the moving parts, so the moving parts are not subjected to whatever is in the water. You still need to rinse the ambient pressure section, but it's not critical to do as thorough a job.

There's also a sealed diaphragm, but I've run out of time.

Edit: illustrations are from Mechanism of diving regulators - Wikipedia