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Regulator & Needle Valve Specs & Selection

Whew! So much discussion on what some folks say is not "rocket
science"....... but while some posts seem to come close, nobody seems to
have grasped what I think is the problem. Regulators and valves come with
"spec sheets" which describe, in technical terms how they will perform.
While some of you might be familiar with these things, a lot of us are not,
and merely pointing us in the direction of the "specs" doesn't accomplish
much other than increase confusion and anxiety.

Hopefully, if I you can extend your patience just a tad more, I'd like to
present some "specs" and ask some questions which might shed some light on
the issues.

Note: All of the following assumes a setup consisting of a Regulator +
Needle Valve (no solenoid, no automatic timer or controller) and any
responses should be appropriate for either a Sintered Glass Diffusor (like
the Eheim or ADA models) or a regular Reactor (like the Dupla "S"). If
known, any differences applicable to use of either end use appliance should
be outlined.

A. - Gass Grade & Regulator Construction:

On the BOC Gases web site, they have a chart which is supposed to help you
select the correct regulator for different gases. Under CO2, they list three
"grades" of purity and there are two different regulator models recommended,
depending upon the grade of gas you use.

Grade of CO2                                        Regulator Model
Research Grade 99.999%                       BHS500/270
Instrument (Coleman) Grade 99.99%      BHS500/270
Bone Dry 99.8%                                    BGS270

The BGS270 is described as constructed from chrome plated forged brass. The
BHS500 is constructed from chrome plated brass bar stock, while the BHS270
is chrome plated forged brass.

1. Does it make any difference if the regulator is made from forged brass or
brass bar stock?
2. Is there any specific reason why they would recommend a different
regulator for CO2 of differing purity?
3. Are the "beer tap" regulators so many of you are using capable of being
used with the wide variety of "grades" of CO2 which seem to be available
(i.e. "Industrial/Welding", Medical, Food Grade, etc).
4. Is there a real difference here?

B. Regulator Outlet Pressure Range:

Looking at the information available online from Air Products, their General
Purpose, Single Stage Regulator (dual Gauge has the following specs:

Model                        1         2      3       4        5          6
7        8
E11-215A (CGA)   3000    15    280    85   0-3000  100  0-30     1
E11-215B (CGA)   3000    50    850   250  0-3000  100  0-60      2
E11-215D (CGA)   3000  100  1500  250   0-3000  100  0-200    5
E11-215F (CGA)    3000  250  1950  350   0-3000  100  0-400  10

1 - Maximum Inlet Pressure (psig)
2 - Maximum Outlet Pressure (psig)
3 - Capacity (scfh at Maximum Delivery Pressure)
4 - Relief Valve Setting (psig)
5 - Inlet Gauge Range (psig)
6 - Inlet Gauge Graduation (psig)
7 - Delivery Gauge Range (psig)
8 - Delivery Gauge Graduation (psig)

1. Assuming the setup of a Reulator + Needle Valve, which of these models
would be most suitable for our sort of use, and WHY?

C. Needle Valve Specs & Selection:

When I look at the spec sheets of various needle valves, I see  things like
Maximum Working Pressure, Flow Coefficient (Cv) and Stem Taper Angle and
whether or not the valve is capable of cutting off the flow of gas
completely. For example. using the spec sheets for the various valves from

Model             Max Working    Cv       Stem Taper   Capable of Cutoff
Nupro 31        5000 psig           0.04
Series Union Bonnet
Nupro BMG     350 psig           0.019     3 degrees metering
Nupro BMRG   350 psig           0.30     20 degrees regulating
Nupro BMW    700 psig            0.019     3 degrees metering
Nupro BMRW  700 psig           0.30     20 degrees regulating
Nupro L          1000 psig           0.15      5 degrees      can be used
for cutoff service
Nupro M         1000 psig           0.03      3 degrees      not designed
for cutoff service
Nupro S          2000 psig           0.004    1 degree        not designed
for cutoff service

1. Other than price differences, is there a reason why you would select one
valve over another for our purposes?
2. Which "specs" should we be looking at, and what ranges are useful and/or
practical for our purposes?
3. Are there other considerations that I'm missing?


James Purchase