The high precision flow control valves and meters for our selection.

[bettatail]

Hi, this is bettatail from TPT.
Planted tank aqua scape and fish keeping is my life time hobby, and back in 2010, when I started using pressurized co2 on my planted tank, went cheap for the first regulator and it was dead in a couple days then I built a set myself after browsing Rex grigg, left C, Matt F. and couple more other's build threads.
Turned out there were more option on better parts and rooms for improvement at the time, and I showed my research on what to get and could be done. At the time, with plenty of liquidated industrial/lab grade equipment on ebay due to 2008 market crash and production outsourcing to China, it became a carnival for planted tank hobbyists(in the US) who want to DIY their own high end co2 system.

In my opinion, the beauty of a planted tank is always dynamic and momentarily, and the hardware of a complete planted tank setup is part of this art, but static and time lasting -- A DIY high end co2 system is also a part of this static art, which hobbyists can appreciate through their own direct effort.

It became another hobby besides planted tank fish keeping. It is fun to build these custom high end co2 systems, but it is more fun to help people DIY their own high end co2 systems and enjoy the accomplishment.

There are several threads listed the flow control valves selection for high end DIY co2 system, the original metering valve selection thread was back in 2011, and in 2020, I made a second selection thread includes all the low flow precision glass tube flow meter models that I could find, and start a discussion on the flow meters.

The lab/industrial high precision flow control devices now a day are mostly Mass flow controllers/meters, I was lucky enough to get a couple of low flow MFC and multiple of glass tube flow meters since 2012, only reveal the glass tube flow meters in 2020 selection thread after I gained enough samples and personally tested most of them. The Mass flow controller is another dimension due to their high cost and rarity, I don't make any list of MFC because they are out of reach for average planted tank hobbyists, but anyone is welcome to try.

here is the list of high precision flow control valves, cartridges, and glass tube flow meters.(base on 2020 TPT Edition, new update marked as 2025)

 

[bettatail]

(base on 2020 TPT Edition, new update sections marked as 2025)

Precision Metering valve, needle valve and flow control/controller

This is a new info thread, the old thread started in 2011, I have stopped adding info since 2014, six year passed.

The old metering valve selection thread

--Metering valve:
Most are high precision flow rate control valves, they are easy to adjust low flow rate and prevent/limit unexpected flow rate purge caused by the regulator output pressure fluctuation/drop.

--Low flow control flowmeters:
control and monitor actual steady co2 flow rate. These flowmeters often can be found equipped with high precision flow control valves. No bubble counter needed. Check Brooks, Porter, Aalborg, and Matheson valves below.

* Cv value. There is a math/formula to calculate the CV value for metering valves. For our co2 pressurized system, a metering valve that can handle the gas flow CV rate down to approximately 0.00025(output pressure 40psi, back pressure 25psi, at 15sccm), is within the precision range.
The CV value of different metering valves on this thread, are "max", so to see if within the 0.00025 range, check their official .pdf for CV vs. Turn chart.

*Why 15 SCCM?
Typical flow rate for a 5lb co2 cylinder/tank, on a 6 month, 8 hours a day usage.
5lb co2 tank X 243 liter/LB X 1/6month X 1month/30days X 1day/8hours X 1hour/60minutes = 14sccm(or 14ml/minute)

* Optimal co2 output pressure
The best output pressure setting for easy co2 flow control/adjustment on a high precision metering valve, is approximately regulator output pressure equals 1 and 1/2 of back pressure.
Back pressure--The pressure down range of a metering valve(Normally the working pressure of a diffuser plus check valve holding pressure).

Pneumadyne (Pneumatic Control System), made in UK
[STRIKE]700 series needle valve[/STRIKE], Part number: C070301/C070501/C070601,
Orifice: N/A
Cv: 0.09 (at 12 turn full open)
This valve is not a precision control valve.

Clippard
MNV-3/4 series needle valve, part number MNV-3* , MNV-4*
Orifice: 0.07"(MNV-3), 0.067"(MNV-4)
Cv: N/A (at 4 turn SCFM is 1, Cv is under 0.03 before 4 turns, after 4 turns, Cv spike)
This valve is not a precision control valve.

SMC
AS1000 Series needle valve, Part number AS120?-*
Orifice: N/A
Cv: N/A
This valve is not a precision control valve.

Ideal valve
52(brass)/54(stainless steel)--1 series, Part number 52-1-, 54-1-
Orifice: 0.0313"
Cv: 0.019 (at 20 turn, 22-24 turn full open, approximate Cv 0.008 -0.009 at 10 turn)
52(brass)/54(stainless steel)--2 series, Part number 52-2-, 54-2-
Orifice: 0.0625"
Cv: 0.082 (at 20 turn, 22-24 turn full open)

Fabco-air
NV55/FC55 needle valve, Part number NV-55, NV-55-18, FC-55
Orifice: N/A
Cv: N/A

Swagelok precision metering valve,
S series high precision metering valve, Part number SS(B)-SS* , SS(B)-SM*
Orifice: 0.032"
Cv: 0.004 (at 10 turn full open)
double pattern, dual handles
Cv: 0.001 ( at 10 turn full open)
M series metering valve, Part number SS(B)-?MG*, SS(B)-?MA*
Orifice: 0.056"
Cv: 0.03 (at 9 turn full open)
double pattern, dual handle
Cv: 0.026 ( at 9 turn full open)
21/22 series metering valve, Part number: -21???-, -22???-,
Orifice: 0.02"
Cv: 0.007 (at 8 turn full open)
[STRIKE]Swagelok O series needle valve, soft seat stem. Part number SS(B)-OR*[/STRIKE]
Orifice: 0.08"
Cv: 0.09 (at 8 turn full open)

Parker Hannifin
(Bronkhorst)HR series high precision metering valve, there are 7 models, mark number from 0 to 6.
Stem type 0, Part number: -H0?---
Orifice:N/A
Cv: 0.0004 (at 15 turn full open)
Stem type 1, Part number: -H1?---
Orifice:N/A
Cv: 0.007 (at 15 turn full open)
Stem type 2, Part number: -H2?---
Orifice:N/A
Cv: 0.014 (at 15 turn full open)
Stem type 3, Part number: -H3?---
Orifice:N/A
Cv: 0.021 (at 15 turn full open)
Stem type 4, Part number: -H4?---
Orifice:N/A
Cv: 0.032 (at 15 turn full open)
Stem type 5, Part number: -H5?---
Orifice:N/A
Cv: 0.049 (at 15 turn full open)
(model 1, 2, 3, 4 are ok, 5 and 6 can not satisfy low CV threshold, well discuss in 2014 but fail to mention in selection thread, add 2025)

Parker NS and NM series metering valve
NS series, Part number -NS?---
Orifice: N/A
Cv: 0.042 (at 14 turn full open)
NM series, Part number -NM?----*
Orifice: N/A
Cv: 0.055 (at 14 turn full open)

Porter/parker Flowmeter
With NR series flow control valve (0,1,2,3) or low flow (Normal) needle valve
low flow tube number:
F65/65 flowmeter a-125-3 ; a-125-5.
F150/150 flowmeter b-125-6; b-125-10 ; b-125-20.
[STRIKE]Flowmeter scale/air to co2 flow rate conversion charts are available on official website.[/STRIKE]
Flowmeter tube calibration data available but they are hidden on official website

Hoke
Micromite 1600 series metering valve.
Orifice: 0.031"
Cv: 0.0008 (at 18 turn full open)
Millimite 1300 series metering vale, 1 degree angle stem.
Orifice: 0.047"
Cv: 0.011 ( at 18 turn full open)
Millimite 1300 series metering vale, 3 degree angle stem.
Orifice: 0.047"
Cv: 0.024 ( at 18 turn full open)
[STRIKE]Hoke 2300 series metering valve[/STRIKE], 1 degree angle stem
Orifice: 0.062"
Cv: 0.01 (at 20 turn full open )

Brooks instrument
Low flow NRS needle control valve, Model 8503, 8504, 8513, 8514.
8503, angle pattern, normal handle
8504, straight(inline) pattern, normal handle
8513, angle pattern, digital handle
8514, straight(inline) pattern, digital handle
stem type Cv.
type 6, CV: 0.052
type 5, CV: 0.017
type 4, CV: 0.0057
type 3, CV: 0.0013
type 2, CV: 0.00066
type 1, CV: 0.00029
These valves are also found on Brooks Sho-rate and OMEGA flowmeters.
Brooks Sho-rate 1350/1355 flowmeter low flow glass tube model number:
R-2-65-A, R-2-65-B (1350)
R-2-15-AAAA, R-2-15-AAA, R-2-15-AA [STRIKE]R-2-15-D[/STRIKE] (1355)
[STRIKE]Flowmeter scale/air to co2 flow rate conversion charts are available on official website.
[/STRIKE]Flowmeter tube calibration data not available on Brooks official website
--Brooks pressure flow control valves model 8744, 8944, 8844 and some others, are combined with NRS valves as well.
(model 1, 2, 3, 4 are ok, 5, 6, 7 can not satisfy low CV threshold, well discuss in 2014 but fail to mention in selection thread, add 2025)

Key instruments
(Now belongs to Brooks instruments)
Key instruments CVP valves (precision control valves)
8 models, model 1,2,3 are really good for low flow control
key instruments flowmeters:
Model GR/GD, low flow tube number 1G01, 1G02, and 6G01, 6G02.
(New version of GR/GD are Brooks 1250/1255 flowmeters, low flow tube number D6011, D6021, D6023,/ D1021, D1022)
GS series, low flow tube number GS101*,GS102*.
Flowmeter tube calibration data not available on Brooks official website

Aalborg/Dakota High precision metering needle valve
there are 6 models of this valve, model 1, 2, 3 are ok for low flow control.
(VM cartridges model 1, 2, 3, add 2025)
These valves are often found on
aalborg/cole palmer/gilmont 150mm and 65mm flowmeters.
low flow Glass tube models for flow meter: 032 tube, 042 tube, and 052 tube with glass floating ball.
[STRIKE]Flowmeter scale/air to co2 flow rate conversion charts are available on official website.[/STRIKE]
Flowmeter tubes calibration data not available on Aalborg/cole palmer official website

Matheson
4170 precision metering valve, High Accuracy
There are 6 models, model 1, 2, 3 are ok for low flow control.
These valves are often found on matheson flowmeters.
FM1050 flowmeter, low flow glass tube models number: 610A(E910), 600(E100), 601(E200).
Flowmeter scale/air to co2 flow rate conversion charts are available on official website.

Dywer flow meter
Series DR Glass flowmeter(same as Matheson FM1050/FM1000)
Series VA Glass flowmeter(same as Aalborg/Cole Palmer 150mm and 65mm flowmeter)
Series RMA polycarbonate flowmeter, model RMA-151, RMA-150


Bellow are some more other good valves, rare or exotic.

Ham-Let metering valve
HXF1300 series metering valve, 1 degree stem angle, Part number HXF13??--
Orifice: 0.03"
Cv: 0.004 (at 11 turn full open)
HF1300 series metering valve, 3 degree stem angle, Part number HF13??--
Orifice: 0.055"
Cv: 0.03 (at 11 turn full open)

Fujikin metering valve , made in Japan
PUN series metering valve, made in Japan
Orifice: N/AMM
Cv: 0.004 (at 10 turn full open)
UN/DUN series
Orifice: 1.5MM
Cv: 0.015 (at 14 turn full open)
UN series metering valve, L mark on top of the vernier handle, made in Japan
Orifice: 1.8MM
Cv: 0.03 (at 14 turn full open)

Mott porous metal flow restrictor
Some models of the Mott flow restrictors provide co2 flow rate good for planted aquarium, specific detail please check official website(Mott Corp.)
(Preset static flow volume, can only be adjusted by increase/decrease input/inlet pressure, not a long term flow control device for our application, high purity only. add 2025)

Porter(parker)
VCD-1000 pressure flow controller
(hewlett packard HP19362)

Kofloc/kojima precision needle valve,
2412 series, 2203/2204 pressure flow controller

Vogtlin High Precision flow control valve,
M-flow micro flow valve, Made in Germany
(NS1.0, NS1.5, NS2.0 models, add 2025)

Witt Gas,
high precision metering valve.

Chell Ultra-Fine Mechanism Needle Valve, Made in UK
Also name Negretti, or Meggitt

Vacoa/Vici/condyne valve

Circle seal valve
(mv92 , add 2025)

Please let me know if you see any other metering valves that not here and can be used in our DIY CO2 pressurized system.

 

[bettatail]

Years away from 2010, the high precision low flow control valves and flow meters are less common on ebay, but once in a while a good/low price right model shows up, and US ebay is open to the UK/global market.

Enough patience and understanding what parts you can get will eventually land you a collection of right parts, then you can DIY a high end co2 system yourself.

Some example of the high end DIY co2 system with all the industrial/lab grade parts.

 

[Fishfur]

Even used, this gear is far from inexpensive & I wish I knew more about this whole topic. But it’s interesting.

 

[bettatail]

Even used, this gear is far from inexpensive & I wish I knew more about this whole topic. But it’s interesting.

Chell Ultra-Fine Mechanism Needle Valve
Check this ebay listing, it is a Negretti Zambra valve, same as morden Chell MNV.
it is in Canada, and it is the only openly available Chell/negretti valve on ebay. It is the 1/16 OD tube ports, need special convertor/adapters.

Negretti vacuum / pressure valve part number 145-217-2P2PK-XXE | eBay

You are looking at a Negretti vacuum / pressure valve part number 145-217-2P2PK-XXE. This unit is functional, it was pulled out of a functional VG Autospec unit.

www.ebay.com

There are some good solenoids from Canada too, on ebay, extremely low power consumption stainless steel aerospace grade valves for only about $40, retail probably in the $300. If interested PM me I will show you the ebay link.

 

[bettatail]

Parker/Porter flow meter B-125-6 glass tube, gives you actual co2 flow volume.

The flow control valve on this flow meter is a porter low flow control needle valve, not the HR series high precision cartridge/metering valves, so it is a little bit touchy.
Pressure in tube, about 0 psig(14.7 psia)-- flow control valve at the bottom position, no blockage/back pressure after the flow control valve. Regulator output pressure is preset, at 50 psi.


co2 flow data sheet for this B-125-6 glass tube flow meter, with black glass floating ball.

 

[bettatail]

Most of the planted tank hobbyists in this forum are from UK, and the UK domestic high precision flow control valve is the Chell Ultra fine Mechanism needle valve.

Model 1 and model 2 are good to handle the low flow control precision requirement on our planted tank co2 injection. They are either swagelok compression port or VCR port, need adapter fittings to convert to NPT or BSPT/BSPP.
Official data sheet of the Chell MNV, click here.
2011 edition Chell MNV data sheet, click here.

This valve has a long tradition, The original trade mark was Negretti valve (corporation), a division of famous Negretti and Zambra. There was another trademark around the time as Negretti valve, which is Meggitt Avionics. I own several liquidated new Chell MNV years back but sold them due to their high value and to full fill their rightful production purpose, it is a waste to put the new valve on our high end co2 system. The used Negretti or Meggitt valve from an old lab equipment? -- I am happy to use them to build DIY high end co2 systems for the planted tank.

It is a high value item on open market, rare if you want it at low cost. I sold the several new Chell MNV and was lucky enough to find equal number of used(Negretti/Meggitt) on ebay from 2010, built two DIY high end co2 systems with them so far.
ebay search key word, "Negretti valve", "Meggitt valve", "Chell Valve". At the moment, there is only one on ebay from Canada, I attached the ebay link in the post above ↑,

1/8 compression ports Chell MNV, model 1

VCR ports Chell MNV, model 2

Meggitt avionics 1/8 compression port with 1/8 NPT adapters, model 2