My RIX SA3-E

[tbone1004]

@iain/hsm so what is your unofficial recommendation for aftermarket filters for the SA3 and SA6 in "normal" consumer type applications. I.e. running in a basement, garage, or dive trailer

 

[SurfLung]

- Iain, I mean no offense by arguing and, I believe everything you have said. But I just can't see why the Solberg intake filters are a bad choice for a sport diver's Scuba compressor. I have seen them on other brands. I think originally the reason I went with the Solberg is because I didn't have a use-able can to just replace the filter element... The filter it came with had the filter element, can, and a brass fitting actually epoxied together.
- Regarding flow restriction, I have actually sucked air through it by mouth and detected no restriction. And, my compressor is pumping at the specified fill rate 2.9-3.1 cfm without increasing rpm. The troubleshooting section of the manual says to check for a flow restriction at the intake filter if the compressor is pumping slow. If its pumping just fine, wouldn't that also suggest that the air intake filter is not restricting air flow?
- I just checked the parts list for my RIX SA3 and the Inlet Filter A77-623 is $224. It certainly MUST be something special for that price... MilSpec to work in all kinds of environments. But is it more than a sport diver like me really needs? I could replace the entire Solberg filter and can 10 times for the same money.

 

[tbone1004]

@SurfLung I think it's more about what the flow is going to do when the filter starts getting clogged from doing it's job. You will probably want to put a differential pressure gauge on there to track filter performance to make sure that you replace it at the right time.
For Funsies, I'll be using this filter on both of my SA6's
https://www.amazon.com/dp/B00H43MP7...olid=1CNTTLER0NU0D&psc=0&ref_=lv_ov_lig_dp_it

WAY overkill being rated at 135cfm, but since the mix-stick I'm using for nitrox is 2", it's much easier to just use that filter than try to adapt it twice.

@iain/hsm out of curiosity, saw that the 1st stage piston is 1.25", but the hose is 1". Is there a reason to have it neck down like that, or did it not matter due to the short intake hose length in the initial design?

 

[SurfLung]

Plumbing Experiments...
- I've been trying to clean up and make my plumbing more compact. This latest effort:
1. Removed the un-needed check valve.
2. Switched to a back mounted gauge.

- It looks clunky to me. My original idea is to have a cross fitting coming out of the moisture condenser. But I ran into male/female fitting problems and had to do it with two Ts instead.
- Also, that last elbow doesn't look like it saves much on space. I could probably run the BPR straight out from the bottom elbow and only stick out an extra inch. Maybe I can angle it back a little... Problems arise with clearance for the rotation required to thread each piece on.
- I have a new T fitting on order with 3 females and one male. This should get it in closer to the moisture condenser. I can attach all three instruments to the T I think and keep the weight of them all as close as possible, too.

 

[iain/hsm]

- Iain, I mean no offense by arguing and, I believe everything you have said. But I just can't see why the Solberg intake filters are a bad choice for a sport diver's Scuba compressor. I have seen them on other brands. I think originally the reason I went with the Solberg is because I didn't have a use-able can to just replace the filter element... The filter it came with had the filter element, can, and a brass fitting actually epoxied together.
- Regarding flow restriction, I have actually sucked air through it by mouth and detected no restriction. And, my compressor is pumping at the specified fill rate 2.9-3.1 cfm without increasing rpm. The troubleshooting section of the manual says to check for a flow restriction at the intake filter if the compressor is pumping slow. If its pumping just fine, wouldn't that also suggest that the air intake filter is not restricting air flow?
- I just checked the parts list for my RIX SA3 and the Inlet Filter A77-623 is $224. It certainly MUST be something special for that price... MilSpec to work in all kinds of environments. But is it more than a sport diver like me really needs? I could replace the entire Solberg filter and can 10 times for the same money.

In your original reply you mentioned four compressor companies that use the Solberg intake filter
(or the Chinese copy version) on their small compressor range for scuba divers, (since deleted).
Namely : Bauer, Alkin, Coltri, and Max Air. There are three reasons for this:

1. They are cheap and compressor customers are too ignorant to know the difference.

2. Or they copied each other or at least three of them did, the forth company wouldn’t use it for the German or the EU market but I guess for the American market sold by an American distributor it’s no problem.

3. Or none of them bothered to do due diligence with the design for a breathing air applications.

That said I don’t think we need to discuss in detail what that specific engineering detail is and end up doing the engineering free for them. But if a customer thinks its OK and is happy then I guess it’s OK.

The other reasons why we would consider not to use that we could discuss further would be as follows:

1. Its a tin can with a powder coated paint finish, It’s fine until rust gets under the paint and paint flakes into the air intake causing damage.

2. Its a rubber moulding edging that seals the paper or polyester filter element, On heating it off gasses into the air intake, Fine for industrial air compressors I guess but not as much so for breathing air. Again OK if we make the choice for ourseves but making it for others creates a problem.

3. Or unless they just copied off each other in ignorance I guess like Alkin, Bauer USA, Coltri, Max Air etc (or the Chinese copy version)

None of the 3 versions above is the main reason for not using it on the SA-3 but enough to illustrate some of the engineering principles at work.

I do agree that the Rix intake filter is much too expensive for recreational users just as is inspecting each and everyO-ring and painting a yellow dot on them to signify its fully passed for intended use. Then again define intended use.

The point I wish to make is that each component on the SA range has considerable engineering detail not always understood or appreciated by the buyers or declared by the supplier. But for some reason we ended up discussing the air intake filter on an SA-3 to death. LOL Iain

 

[iain/hsm]

@iain/hsm so what is your unofficial recommendation for aftermarket filters for the SA3 and SA6 in "normal" consumer type applications. I.e. running in a basement, garage, or dive trailer

Not my job to make specific recommendations your not my customer, but from a forum position where we get to discuss compressors I would add some additional questions we can all apply.
First there would be a difference if the air intake filter was attached directly to the 1st stage in the dry against say fitted on the end of a flexible hose (non off gassing) out in the wet. Further if the intake filter was fitted inside said basement or garage or hanging outside under some tree. Then the design considerations would swing towards considering a non corroding can.

For example consider the original Bauer Filter “can” carefully its made from a moulded “Fibre” reinforced plastic (as opposed to a single polymer plastic) It has a large screw ACME type thread and is made waterproof with the addition of a thin neoprene gasket. In addition the intake horn extends out beyond the side of the can to avoid ingesting rain water and doubles up as a connection port for a flexible hose. Also note the larger diameter post and the increase in diameter at the bottom port of the can where it fits the air intake end of the compressor.

Then the air intake filter cartridge itself is a commercial off the shelf automotive type. Cheap to replace and easily available with many alternative aftermarket suppliers for the cheapskates. Its a good design by engineers who knew what they were doing for the application and use.

Then look again at the Solburg and compare. All this consideration and we haven’t needed to declare anything critical specific or confidential to the SA units. I call that progress for the forum.

 

[iain/hsm]

Just to finsh off the posts about air intake filters for the small SA units
The question I ask myself would be if we were selling the SA again to the diving public what air intake filter would we use or engineer a new one or would we buy in an existing design. So my question is do we:

1. Use the original Rix Mil Spec filter that is clearly overpriced for the retail consumer market.
2. Use the Solburg that doesnt meet the present engineering minimum design requirement.
3. Use the Bauer that meets most of the design requirements except it dont fit.
4. Or design up a new one and go back to item 1.

All the best with those options. Iain

 

[tbone1004]

@iain/hsm why would anything still be confidential on the SA units since it's out of production?

Fair enough with the Solberg being metal, though there aren't really any "off the shelf" intake filter housings out there and production certainly isn't enough on any of these to be using custom molded designs.

You mention filter at the first stage, vs. on the inlet to the hose. Which is better?

Is bigger on these filters bad? I would think not, and I know many people that have adapted automotive air intakes to their compressors and it shuts them up quite nicely. For me the silencing is just as important as anything else.

 

[iain/hsm]

@iain/hsm why would anything still be confidential on the SA units since it's out of production?.

The SA-3 and SA-6 are only out of production in continental USA. They are both still in production in Europe although our applications over here are different and not generally for recreational scuba diving hence we dont use the SA designate number. Maybe this should be revised back to the SA- unit number some how our Model 1S3B-6EH-AQS doesnt quite have the same "ring" to it than SA-6 LOL

Fair enough with the Solberg being metal, though there aren't really any "off the shelf" intake filter housings out there and production certainly isn't enough on any of these to be using custom molded designs.

I quite agree with you, and in addition we would need something that is available both in US and Europe to ensure
same performance and specification, life expectancy, block flow conditions, DeltaP etc .

You mention filter at the first stage, vs. on the inlet to the hose. Which is better?.

Clear winner is to fit the air intake filter on a short length of flexible hose, for your SA-6 its about 3 foot using
3/4" ID hose. ( 1inch OD hose) Gives a slightly increased flow for less power due to a reduction in blow back (as opposed to piston blow by) similar to the "Push-Pull" effect on a breathing loop

Is bigger on these filters bad? I would think not, and I know many people that have adapted automotive air intakes to their compressors and it shuts them up quite nicely. For me the silencing is just as important as anything else.

Again quite agree bigger is better and for the silencing aspect another requirement for the recreational market that is not quite as important for the military. Again the automotive industry have a extensive selection of off the shelf considerations that may achieve the majority of engineering requirents.

If with your SA-6 you are pumping nitrox or heliox using the ubiquitous "stick" method or in the event you are compressing a pure gas such as nitrogen there are a couple of additional engineering considerations you may need to work with we could discuss on a separate post. Iain

 

[SurfLung]

@iain/hsm ...
Fair enough with the Solberg being metal, though there aren't really any "off the shelf" intake filter housings out there and production certainly isn't enough on any of these to be using custom molded designs...

I'm glad to hear that someone else has had an issue with finding an Intake Filter HOUSING. That's the part that is so expensive on the RIX factory set up. I think the replacement filter element is probably only $20 or so. Speaking of housings, I recently found the latest Bauer housing at August Industries. Here's a photo:

They don't give any detail on this housing other than the specific Bauer compressors that it fits. They recommend the following filter element that's designed for it.

Again, virtually no specific information. Either at August or at the Bauer. In defense of Solberg, I just found that they have several lines of inlet and intake filters that might fit the bill... For example you mentioned and advantage of glass filled polymer housings... Solberg has a line of them plus the spec sheets at:
Solberg Filtration | Filter Series Detail | PS Series Plastic Filter Silencers