Two very basic articles on the difference between DSR and SSR Regulators

[Matt F.]

These are some good pieces of literature on taken from the Matheson Tri-Gas catalog. They focus on the issues surrounding the selection of the right regulator for your particular application and why there are certain advantages to using a DSR over a SSR.

Terms like "High Purity" will be defined. It is my hope that with this basic knowledge, you will be able to decipher fact from fiction on other forums whenever the topic comes up.

Common assumption by many aquarists:
1)A good needle valve will prevent EOTD or "the droop effect" with a single stage regulator
This is a false assumption (find out why in the article)

2) EOTD does not affect us when injecting co2 into our aquariums
End of Tank Dump (EOTD) can affect any single stage regulator that is connected to a limited source of gas.

A good intro page to read (differences and definition: DSR and SSR):
http://pdf.directindustry.com/pdf/matheson-tri-gas/regulators/30801-32596.html

End of Tank Dumps are discussed in bullet point #2:
http://www.mathesongas.com/pdfs/products/Regulator-Selection-and-Performance.pdf

These links can also be found on Page 1 of Left C's Dual Stage Regulator thread here at The Barr Report:
http://www.barrreport.com/showthread.php/6470-Dual-Stage-Regulators

 

[barbarossa4122]

Great info. Thanks Matt.

 

[Jim Miller]

Some quesstions:

I know EOTD has been the traditional descriptor for an unexpected rise in CO2 output but is "dump" really the proper characterization? There is a definite, predictable rise in output pressure in response to input pressure drop. A rise of 8lbs would be significant and troublesome if the working pressure was set at 10lbs with a 30ppm target but much less so if the working pressure was 30lbs with a 20ppm target.

Does anyone have any data on the reliability/durability of non-stainless diaphragms when used with CO2?

For those of you who are using $$ needle valves with vernier knobs: are they still being used nearly closed? Is the vernier just there to make the "nearly closed" adjustment less twitchy? Are they still 3 degree taper?

Thanks

Jim

 

[Matt F.]

Some quesstions:

I know EOTD has been the traditional descriptor for an unexpected rise in CO2 output but is "dump" really the proper characterization? There is a definite, predictable rise in output pressure in response to input pressure drop. A rise of 8lbs would be significant and troublesome if the working pressure was set at 10lbs with a 30ppm target but much less so if the working pressure was 30lbs with a 20ppm target.

The tech term according to the article is "droop." This accounts for an increase or decrease in working pressure as inlet pressure changes.

Does anyone have any data on the reliability/durability of non-stainless diaphragms when used with CO2?

SOme CO2 regulators come from the factory with neoprene/cloth diaphrams. I would assume they are reliable/dependable. The VTS253 series models comes with neoprene diaphrams. They are perfectly fine for CO2 in an industrial setting. Where gas purity is important, you should use high purity regulators, which employ the stainless (usually 316) diaphrams.

Look at the specs on the VTS253 (page 33):
http://www.thermadyne.com/IM_Uploads/doclib_4105_Victor Pro Two Stage 31-33_65-2007.pdf


For those of you who are using $$ needle valves with vernier knobs: are they still being used nearly closed? Is the vernier just there to make the "nearly closed" adjustment less twitchy? Are they still 3 degree taper?

Ideal valves utilize 22-24 turns from closed to open full. The vernier/micrometer handles are only for orientation when adjusting co2 injection. It gives you a focal point. These valves are anything but twitchy.
Here are the specs for brass:
http://idealvalve.com/52-series-forged-brass-needle-valves.html
Here are the specs for stainless:
http://idealvalve.com/54-series-forged-stainless-needle-valves.html

Here is how you adjust:
http://www.barrreport.com/showthread.php/7971-How-to-adjust-your-Ideal-Valve

Here is a pic of my brass one so you can see the vernier/micrometer:

Thanks

Jim

My responses are in bold.

 

[Jim Miller]

Hi Matt

Thanks for the detailed response!

Re: stainless vs neoprene. If the neoprene is reliable I don't see a "high purity" issue with aquarium use. We aren't doing gas chromatography. The air in our homes and offices is variable in it's content. Agree?

I see the dial on the needle valves. It doesn't look like "vernier" markings I'm used to on micrometers (differential markings on stationary and moving pieces) but it does look useful. It looks like a simple non-vernier index mark in the pictures I've seen. Are there differential markings on the stationary body other than the one shown?

I think the real benefit in these is the 1*21' taper rather than the 3* taper than most "fine" needles I've seen. How many turns from the seat do you find yourself running for 1-2bsp? At that point what does moving a "mark" result in terms of output change?

Thanks again

Jim

 

[Left C]

Just to touch base on something that might confuse some people. Regular regulators do allow some atmospheric gases to vent into the regulator when being used which contaminates this gas to a small degree. "High purity" regulators do not vent into the atmosphere when connected properly. Also, they don't let any gases from the atmosphere to vent in. Because of their design, high purity regulators can run pure gases through them and the gases will remain pure. If you want to run a gas mixture through high purity regulators, you can still do it without any contamination.

High purity dual stage regulators may be considered overkill for our use, but since their prices on ebaY don't usually reflect their elevated list prices and they are usually around the same price as a regular brass dual stage regulator; they deserve another look. With high purity regulators, you get the stainless steel diaphragms and many have chrome finishes. There are some high purity models that have stainless steel bodies instead of brass bodies. For these reasons, I recommend them. Victor's SGT500 and HPT500 models are extremely nice. Their HPT270 models are nice too, but they are a bit larger. There is a GTP270 model, but it has neoprene diaphragms.

 

[Jim Miller]

Hi LeftC

I see nothing wrong with using some that is overkill as long as it is within the budget. I'm merely trying to discriminate between that which is necessary for some level of proper operation and that which unnessary but perhaps provides esthetic value.

As far as I've been able to determine the minimum two stage necessary is a brass body with neoprene diaphragms. The remainder is beauty for the eye of the beholder or bragging rights.

Am I missing something?

Jim

 

[Matt F.]

Just to touch base on something that might confuse some people. Regular regulators do allow some atmospheric gases to vent into the regulator when being used which contaminates this gas to a small degree. "High purity" regulators do not vent into the atmosphere when connected properly. Also, they don't let any gases from the atmosphere to vent in. Because of their design, high purity regulators can run pure gases through them and the gases will remain pure. If you want to run a gas mixture through high purity regulators, you can still do it without any contamination.

High purity dual stage regulators may be considered overkill for our use, but since their prices on ebaY don't usually reflect their elevated list prices and they are usually around the same price as a regular brass dual stage regulator; they deserve another look. With high purity regulators, you get the stainless steel diaphragms and many have chrome finishes. There are some high purity models that have stainless steel bodies instead of brass bodies. For these reasons, I recommend them. Victor's SGT500 and HPT500 models are extremely nice. Their HPT270 models are nice too, but they are a bit larger. There is a GTP270 model, but it has neoprene diaphragms.

Those GPTs are nice. They make only the GPT 270, I believe.
The SGT500 and HPT500 are my favorite.
The VTS253A-1993 is nice, too. Left C, does this have stainless diaphrams?
The old label was: HPTC (C for chrome plated) 500. The newer ones have HPT 500 only. The BHT 500 is BOC's private label for the HPT 500 but is nickel plated. The BST 500 is BOC's version of the SGT 500, a stainless bodied regulator.

The stainless nody regulators are less forgiving when removing components. If you pull out the threads, which can happen any time (1-2 out of 10 regulators will do this), the regulator is trashed. I have worked on one of these, and it is nerve wracking.

 

[Matt F.]

Hi LeftC

I see nothing wrong with using some that is overkill as long as it is within the budget. I'm merely trying to discriminate between that which is necessary for some level of proper operation and that which unnessary but perhaps provides esthetic value.

As far as I've been able to determine the minimum two stage necessary is a brass body with neoprene diaphragms. The remainder is beauty for the eye of the beholder or bragging rights.

Am I missing something?

Jim

All you'd need is a base model vts253b-320 (brass w/ neoprene. But recently an HPT 270 with stainless diaphrams (high purity) sold for $19!!!

So, it really depends on what you can get and how much you are willing to spend.
Gerryd and I are the only people I know of that went with new regulators (both VTS253A-1993s).
That was the only way I'd be comfortable building one for someone else. I wanted a brand new one for piece of mind.
That said, I bought a brand new SGT 500 (victor) for what some could consider a lot of $$$ (same price as the new VTS253A-1993 that Gerryd and I bought).
I took the risk and got a cherry Victor badged SGT500, which I am using.
For some it's an obsession. I prob fall into this catagory. I like nice, clean equipment.
A used VTS253 (brass) would do a better job of regulating gas than a brand new milwaukee reg, ime.
Plus it is one heck of a lot tougher.

 

[Jim Miller]

I built an Airgas dual for myself. I hope to score a single stage neoprene victor b model soon for some testing.

Jim

 

[Left C]

I built an Airgas dual for myself. I hope to score a single stage neoprene victor b model soon for some testing.

Jim

Jim, I pawned a new SR250 for $30. It would of been fine for your tests I do believe. It was a C model with a 0 to 100 psi low pressure gauge.

Do you want me to see if I can get it back for you?

 

[Left C]

... The VTS253A-1993 is nice, too. Left C, does this have stainless diaphrams? ...

I don't think so, but I've never seen its specs.

 

[Left C]

Hi LeftC

I see nothing wrong with using some that is overkill as long as it is within the budget. I'm merely trying to discriminate between that which is necessary for some level of proper operation and that which unnessary but perhaps provides esthetic value.

As far as I've been able to determine the minimum two stage necessary is a brass body with neoprene diaphragms. The remainder is beauty for the eye of the beholder or bragging rights.

Am I missing something?

Jim

It wasn't directed at you. I wanted to mention the differences about how the normal regulator and the high purity regulators vent or don't vent atmospheric gases. Some folks don't know this.

 

[Matt F.]

I don't think so, but I've never seen its specs.

Maybe an email to thermadyne is called for...hmmm I'll let you know.

 

[Jim Miller]

Jim, I pawned a new SR250 for $30. It would of been fine for your tests I do believe. It was a C model with a 0 to 100 psi low pressure gauge.

Do you want me to see if I can get it back for you?

Hi Left

My characterization of "soon" was probably premature. So I'll pass for now thanks!

I do plan to do some real life pressure droop testing on regulators. I have some small paintball cylinders that I'll fill with gas only (no liquid) to 800PSI which means they'll start down the curve very quickly. One is only 9oz which will likely be the one I use. I've also got a 24oz which I can use in case there is some issue with tank volume being too small. I've also got a teeny 4.5oz.

I probably can't begin this testing until the fall since I need to move my daughter and configure a climate controlled painting studio for her in my garage. I also want to build the cherry surround for my stand first.

Thanks, but no thanks!

Jim

 

[Left C]

I'm really glad that you are doing this testing. There are so many dark and grey areas.

 

[Jim Miller]

I think it should be fun! When I get ready to do some testing I'll post my methodology and ask for inputs. I'll test what I have and likely ask folks if they have some they would like me to test.

Of course I'll post results.

Jim (retired engineer, still the geek...)