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Thread: Dual Stage Regulators

  1. #1
    Join Date
    Sep 2005
    Burlington, NC

    Two Stage Regulators

    Over the past year or two, there has been quite a stir regarding two stage regulators. Many people have been able to purchase a new or used two stage regulator from individuals, as closeouts, yard sales, from ebay, and other places. Together with a solenoid, bubble counter and very good needle/metering valve found the same way, many people have been able to assemble their own high quality CO2 regulator for planted and saltwater aquariums at a very reasonable cost. Two stage regulators will continue to hold their working pressure steady until the CO2 cylinder is empty unlike single stage regulators which will increase their working pressure when the cylinder nears being empty. Sometimes, dire circumstances can occur.

    Some information that will be found here are the differences between single and two stage regulators, how to build your own regulators, where the deals are, what works great and what doesn't plus anything else that we want to discuss. Part numbers for many items will be given. If you know about vendors that are having a sale, feel free to post it.

    Unlike some places, you may leave ebay links and post information. They are welcome.

    You may post pictures of your regulator, your DIY assembly guide, parts, etc.

    There is already a place on this forum where you may want to trade, swap or sell:

    This thread is for everyone to feel free to join in and discuss, add to or to question. In the beginning, there will be information that some people may have seen already, but it will be helpful for new people.

    EDIT: The Victor thread at TPT isn't a sticky anymore. This is the link to it. It is going to be kept closed.
    Last edited by Left C; 12-17-2009 at 02:19 AM. Reason: Victor thread at TPT is no longer a sticky. Link given.

  2. #2
    Join Date
    Sep 2005
    Burlington, NC
    Some people want to understand the differences between single and two stage regulators a little more as well as how they work or don’t work in some cases. "End of tank dump" is explained even though that phrase is not mentioned. The following comes from a Matheson catalog. It is well written and easy to understand.

    TWO STAGE regulators reduce the source pressure down to the desired delivery pressure in two steps. Each stage consists of a spring, diaphragm, and control valve. The first stage reduces the inlet pressure to about three times the maximum working pressure. The final pressure reduction occurs in the second stage. The advantage of a dual stage regulator is its ability to deliver a constant pressure, even with a decrease in inlet pressure. For example, as a cylinder of gas is depleted, the cylinder pressure drops. Under these conditions, single stage regulators exhibit a “decaying inlet characteristic”; where the delivery pressure increases as a result of the decrease in inlet pressure. In a two stage regulator, the second stage compensates for this increase, providing a constant delivery pressure regardless of inlet pressure conditions. The dual stage regulator is recommended for applications where a continuous supply of gas is required; such as the gas supplied to analytical instruments where constant delivery pressure is critical.

    SINGLE STAGE regulators perform the same function as the two stage regulator using a single step reduction of source to outlet pressure. For this reason, the outlet pressure cannot be as accurately controlled as the source pressure decays. We highly recommend single stage regulators only be used in circumstances where the operator can monitor and adjust the regulator as needed or where the regulator is supplied a nearly constant source pressure.

    Regulator Design & Construction Features

    Last edited by Left C; 12-25-2009 at 02:56 PM.

  3. #3
    Join Date
    Sep 2005
    Burlington, NC
    How to Choose a Gas Regulator That's Right For Your Application



    What is the difference between the Single Stage and Two Stage Gas Regulator?

    Gas pressure regulators are used to reduce the pressure of gas supplied from a high-pressure cylinder of gas to a workable level that can be safely used for operating equipment and instruments. There are two basic types of gas pressure regulators: single-stage and two-stage.

    Single-stage pressure regulators reduce the cylinder pressure to the delivery or outlet pressure in one step. Two-stage pressure regulators reduce the cylinder pressure to a working level in two steps. Since the performance of each is influenced by mechanical characteristics, the choice of gas regulator depends on the type of application for which it is intended.

    The two most important parameters to be considered are droop and supply pressure effect.

    Droop is the difference in delivery pressure between zero flow conditions and the gas regulator's maximum flow capacity. [Supply pressure effect is the variation in delivery pressure as supply pressure decreases while the cylinder empties. For most regulators, a decrease in inlet pressure causes the delivery pressure to increase.

    The effect of these differences on performance can be illustrated with some examples. For instance, when a centralized gas delivery system is supplying a number of different chromatographs, flow rates are apt to be fairly constant. Supply pressure variations, however, may be abrupt especially when automatic changeover manifolds are used. In this scenario, a two-stage regulator with a narrow accuracy envelope (supply pressure effect) and a relatively steep droop should be used to avoid a baseline shift on the chromatographs.

    Single-stage and two-stage gas regulators have different droop characteristics and respond differently to changing supply pressure. The single-stage regulator shows little droop with varying flow rates, but a relatively large supply pressure effect. Conversely, the two-stage regulator shows a steeper slope in droop but only small supply pressure effects.

    On the other hand, if gas is being used for a short duration instrument calibration, a single-stage gas regulator with a wide accuracy envelope (supply pressure effect) but a comparatively flat droop should be chosen. This will eliminate the need to allow the gas to flow at a constant rate before the calibration can be done.

    __________________________________________________ __________________________________________________ _____


    General Gas Use

    The selection of the proper gas regulator involves many factors including body and internal materials of construction. For general use, regulators of brass construction with elastomeric diaphragms will give good service in noncorrosive service where slight contamination or diffusion from an elastomeric diaphragm is not important. Brass regulators with stainless steel diaphragms prevent air diffusion and adsorption of gases on the diaphragm. This is particularly important with low concentration mixtures of hydrocarbons in which the trace component may be adsorbed on the elastomeric diaphragm.

    The gas regulator must be constructed using materials suited to the application. Industrial general purpose regulators are often constructed with either Buna-N or Neoprene diaphragms. Regulators with Buna-N or Neoprene diaphragms are not suitable for GC analysis that can be affected by the diffusion of atmospheric oxygen through the elastomer diaphragm or the outgassing of monomers and dimers from the elastomer. In fact, laboratories that perform temperature programmed analysis are faced with excessive baseline drift and large unresolved peaks due to this diffusion and outgassing.

    High-Purity Gas Service

    The ideal construction for high-purity gas service is a gas regulator that has a stainless steel diaphragm. Such regulators are noncontaminating and assure satisfactory use for all applications of noncorrosive and mildly corrosive gases. Regulators for corrosive gases must be selected from those recommended with each gas listing.

    A gas regulator equipped with a stainless steel diaphragm has several advantages over the elastomeric type. It does not outgas organic materials and it also prevents the diffusion of atmospheric oxygen into the carrier gas. Both Buna-N and Neoprene diaphragms are permeable to oxygen. The chemical potential of oxygen between the carrier gas and the atmosphere provides sufficient driving force for oxygen to intrude the carrier gas through a permeable diaphragm.

    Materials of Construction Summary

    The intended gas service for which the gas regulator is used must be compatible with the materials of construction that come in contact with the gas stream. The wetted materials must be compatible with the gas composition.

    o Noncorrosive (Typical Materials): Aluminum, Brass, Stainless Steel, Buna-N, PCTFE, Neoprene, Teflon®, Viton®, Nylon
    o Corrosive (Typical Materials): Aluminum, Stainless Steel, Monel®, Nickel, PCTFE, Teflon®

    Regulator Gauges

    Generally single and two-stage gas regulators are equipped with two gauges: a cylinder or inlet pressure gauge, and a delivery or outlet pressure gauge. The cylinder pressure gauge has the higher pressure range and is located adjacent to the inlet port. The delivery pressure gauge of lower pressure range is located adjacent to the outlet port. Although most cylinder regulators have two gauges, regulators utilized on cylinders containing liquefied gases may not have a cylinder pressure gauge because the cylinder pressure varies only with temperature as long as liquid is present in the cylinder.

    Operating Delivery Pressure Range

    Determining the delivery pressure range can be confusing. First, it is important to determine the gas pressure that is needed. Second, determine the maximum pressure the system might require (these two pressures are often the same). Third, select the delivery pressure range so that the required pressures are in the 25 to 90% range of the gas regulator's delivery pressure (a regulator's performance is at its best within this range).

    Regulator Placement (Cylinder or Line)

    Specialty gas regulator applications are divided into two types. The first is when the regulator is fastened to a gas cylinder using a Compressed Gas Association (CGA) fitting (or BS or DIN). The second application is when a regulator is located in a gas line - providing a means to further reduce the line pressure. A line regulator is identified by having the inlet and outlet opposite of each other, and by a single gauge which is in the 12 o'clock position to indicate the reduced pressure.

    Buna-N® and Teflon® are registered trademarks of E.I. Dupont de Nemours & Company.
    Monel® is a registered trademark of Inco Alloys International Inc. Viton® is a registered trademark of DuPont Dow Elastomers.

    __________________________________________________ __________________________________________________ ______


    The application determines which gas regulator to select. For example, a brass regulator should not be used in corrosive gas service. The duration of gas use time helps to identify whether a single-stage or two-stage regulator provides the best service. A single-stage is a good performer for short duration gas usage. A two-stage gas regulator performs best when it is attached to the cylinder and adjusted to the desired reduced pressure, and then remains in service until the cylinder is ready for changeout.

    Consider this criteria when planning your next pressure reduction requirements.

    1. Use a gas regulator for all pressure reduction requirements.
    2. Use a valve for flow control.
    3. Materials used in the gas regulator construction are to be compatible with the intended gas service.
    4. Determine the delivery pressure requirements.
    5. Do you need a cylinder regulator or a line regulator or perhaps both?
    6. Determine the accessories to be included with your gas regulator.
    7. Determine how you intend to use the pressure regulator. Generally a single-stage regulator is good for short duration applications; a two-stage regulator is good for long duration applications.
    Last edited by Left C; 12-25-2009 at 02:56 PM.

  4. #4
    This thread is for the DIY user, and is universal regardless of brand, location, etc and can really improve the use of CO2 dosing, which is a huge issue for planted aquarist using CO2 gas enrichment.

    A good high grade CO2 system is well worth every penny spent and can go a long way to resolving issues, and it should also last a lifetime. Add a good needle valve to this and a good solenoid, then you are ready to go!

    I also suggest the same approach for other facets in the hobby, good high grade test kits and methods. Good high grade lighting that you can vary to suit. Good consistent aquarium care, dosing etc. Good nice looking tanks, stands, also, good high grade sediments that you like and can use effectively.

    All these things add up.
    CO2 causes lots of issues and folks kill fish more with this than any other single factor in planted tanks, go 1st class if you can here. If not, work your way that direction as time/$ allows.

    Tom Barr

  5. #5
    Join Date
    Sep 2005
    Burlington, NC
    Atlanta Area Aquarium Association Forum – Victor dual stage regulator

    From: Atlanta Area Aquarium Association Forum / CO2 Regulator

    Post #1: … “What CO2 regulator do you folks recommend?”

    Post #4: “Victor dual stage and don't look back.Donny”

    Post #5: “The best of my three regulators is a victor dual stage also. Got it on ebay for about $50. They aren't as easy to find cheap as they used to be though.”

    Post #6: “They are getting hard to find.I have 2 extras regulators,20 gallon tank(full) and 5 gallon tank (full) that I will sell>>>Donny …”

    Post #7: “I've used many different brands of regulators, some specifically marketed for aquarium applications and many not. Currently on my aquariums I use Milwaukee Regulators, mainly because I bought them cheap and they included a solenoid. I've had no problems.

    If you aren't going to be using a pH controller (and therefore a solenoid), I would go double stage. People like Victors because, as far as double stage regulators go, they are less expensive(especially used) and dependable.

    If you are interested in using a controller, the controller/solenoid will handle any ill effects caused by end of tank dump associated with single stage regulators.

    If you can find a Victor double stage for $50, buy it. You can always pick up a solenoid later for $20 or less.

    Post #8: “I concur with Donny. I been using a used Victor dual stage CO2 regulator for 9 years now and it had to be at least that old when I got it. It has never failed.


    Post #12: “Well, I can get two of these:

    VICTOR - NU AIRE Model No. VTS253A1993
    Dual Stage, Dual Gauge, Chrome Plated Brass Heavy Duty Pressure Regulator for Standard CO2 (Carbon Dioxide) Cylinders (CGA320 Fitting)

    for $70.00 each. Is there any reason to get two? Does anyone want to buy one? Otherwise, I think I will just get one.”

    Post #15: “VTS253A is the regulator a lot of posters on plantedtank were buying off of Ebay. Think I paid about $50 for mine about a year ago. About 3 to 6 months before I bought mine they were going for $30 to $35 on ebay. So many planted tank people were scooping them up that the price shot up. It is big and heavy and probably overkill but a excellent regulator.”
    Last edited by Left C; 02-14-2012 at 08:33 PM.

  6. #6
    Many thanks for this topic,

    if something like this was written/stickied before, I'd never bought the regs I have now

    In Europe, Pangas and Carbagas provide common gases+CO2/Argon regulators, single and double stage, for all purity grades, corrosive and non corrosive gases

    By the way, an addition with some lines on needle valves would be great. For now, I find Ideal valves the best (the 1/32" series)

    Also, some single stage regulators do better than others with keeping a steady pressure. The Tunze one is of good quality and its needle valve is enough fine. But, its price makes it not worth a dual stage
    Aquatic Natur Cocoon 7: 11gal, dry start success / low light / CO2
    >>Follow it here<<

    Aquatlantis Evasion 120: Stopped ---> Malawi setup = No Plants

  7. #7
    Join Date
    Sep 2005
    Burlington, NC
    Quote Originally Posted by jonny_ftm View Post
    Many thanks for this topic,

    if something like this was written/stickied before, I'd never bought the regs I have now ...
    Your are very welcome. We hope that we can help some people to make a better decision.

    Like Tom said, "A good high grade CO2 system is well worth every penny spent and can go a long way to resolving issues, and it should also last a lifetime. Add a good needle valve to this and a good solenoid, then you are ready to go!"
    Last edited by Left C; 11-18-2009 at 08:41 PM.

  8. #8
    Join Date
    Jan 2008
    Kansas City, MO
    I picked up a new Swagelok SS-2MG-MH-SS11 needle valve (1/8") on eBay over the weekend for $52 shipped. I"m not sure that's a good price but I wanted to go with a swag this time around (I have an Ideal on my other tank).

    The seller still has seven left but it's a "Buy Now" only auction. The URL is: { }

    Thanks to Tom and Left_C for giving this thread a new home.

    - Brad
    Last edited by bradac56; 11-18-2009 at 11:40 PM. Reason: Me no spell good.

  9. #9
    Quote Originally Posted by bradac56 View Post
    I piked up a new Swagelok SS-2MG-MH-SS11 needle valve (1/8") on eBay over the weekend for $52 shipped. I"m not sure that's a good price but I wanted to go with a swag this time around (I have an Ideal on my other tank).

    The seller still has seven left but it's a "Buy Now" only auction. The URL is: { }

    Thanks to Tom and Left_C for giving this thread a new home.

    - Brad
    If they had some threaded male ends/not the tubing ends, then it would be a great deal.

    Ideal's are good/better a bit, but harder to find and more $.

    Tom Barr

  10. #10
    Which clippard solenoid should I purchase in order for me to add my own power cord? The ones listed on aquarium sites sell them for almost $30 bucks. Left C also posted one that I can find under $20 bucks. Where can I find that as well?

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