first of all, you are the lucky one to see this post, there is a porter flowmeter same as the one in video on evilbay, if need one, grab one, they are only a fraction of their original price, but don't be greedy, there are other hobbyists who need it too.
evilbay search key word: PORTER INSTRUMENTS B-125-6
Brooks flowmeters, 1355 flowmeter with R-2-15-AAA, R-2-15-AA glass tubes, PM me for CO2 flow rate / calibration data.
there is a new flow meter that we can use, evil bay key word: Adjustable Oxygen Flow Meter 100 psig
it is key instruments 65mm flow meter for oxygen direct reading at 100 psig, and here is co2 calibration measurement for this flow meter(we can use it for co2 )
back in 2013 I acquired a brooks flowmeter with NRS series 1 high precision metering valve, but only in the last several months have seriously looked into it.
while I did the research, on Brooks, Matheson, Parker, Aalborg/cole Palmer .... , I was puzzling by the dwyer flowmeter, because back in 2013 I didn't see anything dwyer have available for our co2 flow range, but some hobbyists found that the RMA 150 model flowmeter work, and work well, so I added dwyer RMA 150/151 to the new metering valve selection list. But still, I didn't see any thread talking about detail info of the dwyer RMA 150/151, until today, I found this thread:
Now I can let you know besides dwyer, there are more high precision flowmeters can be added to our CO2 pressurized system.
The full list of high precision flowmeters can be found in the metering valve selection thread.
metering valve/flowmeter selection thread.
This is a Parker/porter, tested and took the video today.
It is the Parker low flow needle valve on the flowmeter, the flowmeter tube number is B-125-6
for this particular porter flowmeter, the air volume scale chart(pressure: 0 psig/14.7 Psia), then mulitply by conversion factor from air to co2, now the exact co2 flow volume can be calculated, then....
!!! ADD information conversion factor and pressure setting factor 20200313
The flow chart below is the backbone to calculate the actual flow rate of co2. (the flow rate of co2 is at the 70F, 0 psig volume)
1. This flow chart is the AIR flow rate at 70F, 0 psig(14.7 Psia), to find the air flow rate, get the scale reading on the glass tube where the black glass floating ball is, then find the air flow volume on this chart. To convert to co2 flow volume, the air flow volume X 0.81 (0.81 is the air to co2 conversion factor)
2. for anyone use a diffuser or reactor that require some pressure to push co2 through, this flow chart is not adequate, so a second conversion according to actual pressure need to be calculated.
First, you need to turn the inside glass tube up side down, then turn the flowmeter around, so the valve will be on top at the outlet position(bottom is inlet position). Now the pressure inside the glass tube can be adjusted the same as the regulator output pressure.
Second, according to the pushing through pressure of the diffuser or the reactor, the regulator output pressure can be adjusted to 18.5 psig or 45 psig. The conversion factor for 18.5 psig is 1.5, 33 psig is 1.8, and for 45 psig is 2.
actual co2 flow volume at 18.5psig = co2 flow volume X 1.5
actual co2 flow volume at 33psig = co2 flow volume X 1.8
actual co2 flow volume at 45psig = co2 flow volume X 2
if you have a cerge reactor, but with a couple 3 psi pushing through inline check valves, the back pressure is about 6 or 7 psi higher than 0 psig, so it is better to turn this porter flowmeter around while the glass tube inside turn around as well. Now you can set the regulator output pressure at 18.5 psig.
After you adjust the flow rate, the glass floating ball settle at 28.0 scale position.
according to flow chart, air flow volume at 28.0 position is 5.20sccm(cc/m), convert to co2 volume is 5.20sccm X 0.81, then convert to pressure setting at 18.5psig is 5.20sccm X 0.81 X 1.5 = 6.32 sccm
so the actual co2 flow volume is 6.32 sccm
if you have an atomic type diffuser, require around 25-30 psi push through pressure, might as well turn around the glass tube and the flowmeter, then keep the regulator output pressure as well as the pressure in the glass tube at 45psig.
Now this time you want to set the actual co2 flow volume at 15sccm(cc/m), you can calculate everything backward.
15 sccm = Air flow volume X 0.81 X 2
Air flow volume = 9.26 sccm, according to the chart, the scale reading is 60.0, so you adjust the valve until the glass floating ball settle at 60.0 to achieve 15sccm co2 injection.
All wrong above, please do not follow, my apology.
A flowmeter can be set into two positions, turn around the flowmeter and the glass tube inside.
Position 1: flow control valve at the top(outlet), the pressure inside the glass tube is the same as the regulator output pressure, a steady flow rate at certain regulator output pressure can be monitored, this position is more useful/practical to read the actual co2 flow rate in our application.
Position 2: flow control valve at the bottom(inlet), the pressure inside the glass tube is the same as down the flow line pressure, 0 psig can be achieved in this position.
here is the real co2 flow rate data at 1 ATM (0 psig, or 14.7 psia, 70 degree), for Parker/Porter flow meter B-125-6.
scale --flow rate(SCCM), flow meter position 2.
and I will measure the actual co2 flow rate under different pressure.
(bear with me, too long to read, :P)
The precision flowmeters enable us to control the exact amount of co2 injection to our planted tank, so as well laying the path for new co2 injection methods.
--With the flow meter, we know the exact flow rate of the co2; In addition, once the total time of injection is given, we know the exact amount of co2; now, plus the given water volume, we can calculate the increased CO2 ppm!
The whole calculation process omitted, but the result is here:
if co2 dissolve into water at 100% efficiency, to increase from 0ppm to 20 ppm:
Actual co2 flow rate = 6.4 sccm X (water volume in gallon/ 10 gallon) / (Total hours of injection)
6.4 sccm(cc/m, 0 psig, 70F) co2 flowrate in one hour will increase co2 concentration from 0 to 20 ppm in 10 gallon of water.
3.2 sccm(cc/m, 0 psig, 70F) co2 flowrate in two hours will increase co2 concentration from 0 to 20 ppm in 10 gallon of water.
1.6 sccm(cc/m, 0 psig, 70F) co2 flowrate in four hours will increase co2 concentration from 0 to 20 ppm in 10 gallon of water.
16 sccm(cc/m, 0 psig, 70F) co2 flowrate in two hours will increase co2 concentration from 0 to 20 ppm in 50 gallon of water.
16 sccm(cc/m, 0 psig, 70F) co2 flowrate in four hours will increase co2 concentration from 0 to 20 ppm in 100 gallon of water.
In normal condition, the co2 concentration in water is 0-10 ppm, and planted tank hobbyists normally aim for 20+ ppm co2 in their tanks(but no more than 30ppm).
now with a precision flow meter, how much co2 in volume and its increased concentration in the planted tank can be predicted
From this point we can derive the new co2 injection methods:
method 1, single injection.
The co2 injection starts before the light turns on, concentration of co2 in the water will reach its peak, at 20+ ppm around the time light turns on. The injection rate depends on light intensity and mass of the plants in the planted tank, need observation to set the actual flow rate. Higher the injection rate, shorter the start time before light turns on, vise versa.
for a high light, heavy planted 50 gallon tank, the co2 injection rate can be set at 8 sccm four hours before the light turns on. when the light turns on, the co2 concentration is 20+ ppm at its peak, and will stay or slowly lower down with continuous 8 sccm injection.
for a medium light, moderate planted 50 gallon tank, the co2 injection rate can be set at 4 sccm eight hours before the light turns on, the co2 concentration will reach its peak(20+ ppm) when the light turns on, and will stay or slowly lower down with continuous 4 sccm injection.
The core for method one is to maintain a safe co2 injection rate, while the 20-30ppm co2 concentration can be achieved by starting the co2 injection early before the lights on.
method 2, dual solenoids injection.
this setup require two solenoids, first solenoid connects to timer that turn on/off before the light turns on. Second solenoid can be kept on the same schedule as lights.
1.when first solenoid is on, the co2 flow rate is decided by metering valve 1 on the flowmeter, this metering valve must be set for larger flow rate.
*Second solenoid on or off is not matter while the first solenoid is on.
*First solenoid and metering valve 1 are in control to increase/boost CO2 concentration to 20+ppm.
2.When first solenoid is off, second solenoid is on, the co2 flow rate decided by metering valve 2.
*This flow rate is on small flow rate, to replenish the lost/decrease co2 ppm in the water column.
*second solenoid is on while the light turns on.
3.when both solenoid are off, co2 flow stop.
for a high light, heavy planted 150 gallon tank, two hours before the light turns on, first solenoid is on and co2 injection rate at 48 sccm set by metering valve 1.(or 96 sccm co2 injection for one hour)
when the light turns on, co2 concentration in the water is 20-30 ppm, now the first solenoid is off, second solenoid is on while the metering valve 2 set at 24 sccm flow rate.
for a low light, moderate planted 50 gallon tank, the co2 injection rate can be set by metering valve 1 at 16 sccm while solenoid 1 turn on for 2 hours, to increase the co2 concentration to 20-30 ppm, then solenoid 1 turn off.
Solenoid 2 turn on, this time the metering valve 2 control the co2 flow rate at 4 sccm, for the lights on injection.
2 solenoids, 1 flowmeter with valve, 1 metering valve. The metering valves must be placed AFTER the flowmeter, so the desired/set pressure can be hold steady in the glass tube/flowmeter. Metering valve 1 large flow rate, metering valve 2 small flow rate.
2 solenoids, 2 flowmeters with valves. The metering valves flow rate are independent in this setup.