Info Function checking a regulator after service

[Dan]

2. Take a few breaths off each 2nd stage. I don’t bother to measure 2nd stage cracking effort (most divers are not going to invest in the equipment needed to do that anyways) I have a decent sensitivity to how they breathe and I trust it. You can too! If it’s nice and easy to breathe and does not start free flowing, that’s good enough.

Before I learned about function checking a regulator after service, I was gasping for air, working hard to breathe through my 2nd stage at the surface, while waiting for my buddy to jump into the water. It turned out that adjuster knob was fully closed. Once I opened that adjuster knob to fully open, I could breathe normally at the surface like breathing on land without the regulator.

So, do check the adjuster knob and adjust it accordingly before jumping into the water.

After the safety stop, while waiting at the surface for dinghy to pick us up, I usually remove the 2nd stage off my mouth, dip it into the water and see if it is easily free flowing or not. If it is, turn the adjuster knob slightly toward closed position.

 

[tursiops]

After the safety stop, while waiting at the surface for dinghy to pick us up, I usually remove the 2nd stage off my mouth, dip it into the water and see if it is easily free flowing or not. If it is, turn the adjuster knob slightly toward closed position.

Wouldn't make more sense to do this at the beginning of the dive?

 

[Dan]

Wouldn't make more sense to do this at the beginning of the dive?

Yes. Unless you’re the last person in the group to enter the water and everyone is waiting for you.

 

[halocline]

Yes. Unless you’re the last person in the group to enter the water and everyone is waiting for you.

You should check that in water before your dive trip. One thing assumed with all this advice is that you have access to a tank to check the regulator. Everybody has a tub of sorts and some water, I assume.

For casual divers that don’t have access to a tank at home, the only way to check your regulator is to either borrow a tank or bring it to a shop and use a tank there.

That said, even for a casual vacation-only diver, having a small scuba tank around the house is pretty handy; in addition to using it to check your regulator, you can fill tires with it, you can get a small air nozzle that fits on the LP inflator hose and use that for various things, etc. It’s not expensive at all to get a used 19 or 30 cft bottle.

 

[chthonicly]

You should check that in water before your dive trip. One thing assumed with all this advice is that you have access to a tank to check the regulator. Everybody has a tub of sorts and some water, I assume.

I wouldn't actually make that assumption. For my first 2 years diving, my 4th floor apartment (in a building with no elevator) did not have any tubs. I had no access to faucet water at street level to fill up a plastic bin, furthermore, I had no space for an extra plastic bin big enough to fit a tank. I also never brought my tanks up to my apartment, so fiddling around with putting a tank on a reg meant hanging out at my car on the side of the street. It was much easier for me to just *dive* a reg set, as I am a local diver and the dive sites are about an hour from my apartment.

So whenever I got a reg back from service I would just go dive it at the easy check out site. The world never ended so even now that I moved to a place with a bathtub, I still just go dive the regs. Just seems easier. Worst case, I breathe my necklace for that dive and keep the profile conservative and take it back to the shop.

 

[halocline]

I wouldn't actually make that assumption. For my first 2 years diving, my 4th floor apartment (in a building with no elevator) did not have any tubs. I had no access to faucet water at street level to fill up a plastic bin, furthermore, I had no space for an extra plastic bin big enough to fit a tank. I also never brought my tanks up to my apartment, so fiddling around with putting a tank on a reg meant hanging out at my car on the side of the street. It was much easier for me to just *dive* a reg set, as I am a local diver and the dive sites are about an hour from my apartment.

So whenever I got a reg back from service I would just go dive it at the easy check out site. The world never ended so even now that I moved to a place with a bathtub, I still just go dive the regs. Just seems easier. Worst case, I breathe my necklace for that dive and keep the profile conservative and take it back to the shop.

Even a kitchen sink would do the job with a small tank, like a 13 cft pony. And that’s not a useless tank to own; some people like to carry a small pony on OW dives (I don’t, but that’s a personal decision) and having compressed air around the house has it’s uses from time to time.

 

[NothingClever]

If your 2nd stages have adjuster knobs, the regulator should free-flowing when fully open and not free-flowing when fully closed.

I recognize that’s your standard but I don’t think it’s something to promote for Basic divers. For that matter, the more advanced divers become many find reasons to detune their regs.

 

[Nemrod]

This thread has a lot of misinformation or at least some confusion.

Most modern regulator second stages have two external controls. One is the Venturi usually indicated as Dive/Pre-dive or Max/Min. The second control is usually a knob that controls spring tension, the force applied to the seat upon the orifice when static. Atomic regulators have an automatic Venturi control so they only have the seat tension adjustment.

A second stage properly adjusted to any service manual should not free flow or leak just sitting there.*

With the second stage tension knob fully out and the Venturi in DIVE/Max pressing and then releasing the purge should cause a sustained free flow.

With the second stage Venturi set to pre-Dive/Min the regulator should stop flowing when the purge is released.

Here is the Scubapro instruction for function check in the G250 Service Manual, note the last few bullets. This is typical. Not all SMs use the same wording or description but the intent is essentially the same:



In all cases there is a SM provided cracking effort specification, for example the SM will say that the second stage should begin to flow with 1.1 to 1.6 inches of water column with the knob if present fully turned out. The excerpt from the G250 SM is an example, the specific range for cracking effort to initiate flow may vary for a specific second stage model/brand as may the procedure for checking.

When serviced it is often needed to set the cracking effort/orifice adjustment a little to the high side (but still within specification) so that when the seat breaks in to the orifice, it will not ever so slightly leak (or leak annoyingly ) which will then cause a service return and an upset customer.


(*)Some divers, do in fact set up there personal second stages to ever so slightly leak (not free flow) with the tension knob fully out. I set mine up that way but I would not have for a customer reg. If turning the knob in about a half turn to a full turn does not stop the leak (not free flow) then I make an adjustment to make it so for my personal regulators. Usually a minor orifice adjustment.

(**)Some second stages do not have a Venturi control nor a spring/seat tension knob. An example of a well known second stage many still use commonly is the USD/AL 1085 (Conshelf). In such case the primary should be set to have a sustained free flow when the purge is released and the secondary should be set to stop free flowing when the purge is released. For cold water use, especially those without adjustments, should be set to not free flow when the purge is released. Most SM will show a higher cracking effort range and a lower IP for cold water specific regulators.

In other words regulators should be set per their SM instructions unless you as a diver have the specific knowledge, reasons and tools to do otherwise. Most do not.

And one final thing, there is a widely believed idea that setting the tension knob in (higher cracking effort) or setting the Venturi knob towards Min/Pre-dive will conserve air. No, no, no. This will only cause CO2 increase, higher air consumption not lower because the diver must work harder to ventilate, give the diver a head ache and can be quite dangerous. So why even have the tension knob you ask? It has a use, an example would be if scootering or swimming into a current, the force of the water rushing upon the second stage diaphragm will cause free flows and the diver can usually inhibit that by turning the knob inward to increase tension. Another, a working diver or a photo diver may have to be in a head down position for a lengthy time, this position, head down, may cause a well tuned regulator to free flow, the diver can turn the knob inward to reduce the tendency to free flow.

 

[NothingClever]

Scootering and flow were what I was thinking about with the detuning, not the dorky “workaround” to reduce consumption. That’s a skill/experience problem, IMO.