Speaking of Flow Meters

[JayP]

As I've mentioned one or two times before, I can't resist a bargain. Pictured are 8 Dwyer RMA-151 valveless flow meters. Brand new, these run $65 to over $100 but used on Ebay - $11 each. Yes, you read that right, $11. I just received them today and want to confirm each one works, but I won't need all 8. I'm thinking I will keep 5 and the remaining 3, I will offer up here to 3 people at the $11 I paid plus whatever shipping is, which would probably be $10 to $15 (within U.S.). Give me some time to confirm all are functional over the coming week and then I'll give the green light, first 3 to ask after the green light will get them.

 

[Naturescapes_Rocco]

This is an amazing deal, people! If your tank is between 30-100 Gal, it's likely right for you. If I didn't already use two of these models, I'd pick one up for sure!

 

[JayP]

first 3 to ask after the green light will get them.

LOL! Alright you gun jumpers...and you know who you are , I haven't given the green light yet.

 

[GreggZ]

Wow that's an awesome find!

And very generous of you to share with folks on the forum.

They also come with the 1/8th NPT hose barbs which you usually have to buy as well.

Great deal everyone.

 

[JacksonL]

Love a good bargain. That would have been a thrilling find!

 

[JayP]

This is how the deal will work. I've been reminded we have a forum marketplace, so the green light will come on when I post them there. Preliminary testing indicates they are all basically functional. A couple were initially stuck but it didn't take long to figure out how to unstick them. I'm assembling my first DIY regulator now and I'll use that in the next day or 2 to perform a better test to compare readings of all, with CO2 pressures in the ballpark of what we use. Accuracy is not a big concern for our use but I do want to see all of them read somewhat close to one another.

 

[Bettatail]

Great find! and thanks for providing them to the fellow planted tank hobbyists!

The RMA151 is good for about 0 psig outlet pressure and 3 psi pressure differential within the tube, 5 psi or higher pressure inside the tube start making them inaccurate, other higher precision glass tube flow meters work better but it is all about the cost and availability.
I will generate a generic flow data sheet for them, 15 and 25 psi pressure in tube, data sheet of higher pressure in tube may not be available due to previous test gave me abrupt result due to its polycarbonate passage expansion.

 

[Bettatail]

I can not get a reliable co2 flow data along the vertical scale because the increment is way too much, from the minimum scale reading of 10 to 15, the flow rate just double...

The only reliable method to increase/decrease flow rate is to adjust the regulator output pressure, while always keeping the floating ball at scale 10, and the outlet of the flow meter is about 0 psig(yugang/cerges/rex griggs reactors). The flow control valve is at outlet/top of the flow meter as the Dwyer RMA151-SV setup.

here is the co2 flow data sheet for the Dwyer 151( Dwyer 151-SV),

another flow meter tested today, a Parker/Porter flow meter with A-157 7 tube and glass floating ball, here is the CO2 flow data sheet for comparison.

 

[JayP]

I can not get a reliable co2 flow data along the vertical scale because the increment is way too much, from the minimum scale reading of 10 to 15, the flow rate just double...

The only reliable method to increase/decrease flow rate is to adjust the regulator output pressure, while always keeping the floating ball at scale 10, and the outlet of the flow meter is about 0 psig(yugang/cerges/rex griggs reactors). The flow control valve is at outlet/top of the flow meter as the Dwyer RMA151-SV setup.

here is the co2 flow data sheet for the Dwyer 151( Dwyer 151-SV),

another flow meter tested today, a Parker/Porter flow meter with A-157 7 tube and glass floating ball, here is the CO2 flow data sheet for comparison.

Perhaps @Naturescapes_Rocco can add some detail since he's been using the RMA-151 for some time.

 

[Bettatail]

one more flow data sheet made today, a Parker/Porter flowmeter with A-125-3 tube and glass floating ball.
This flow meter is ok for diffuser with high pressure output, it is a higher precision low flow control device.
If anyone want a A-125-3 tube Porter flow meter, keep an eye out on ebay, it appears from time to time, good luck.


it covers the co2 flow rate from 1 bubble/second to 10+ bubbles/second, 15SCCM flow rate is about 4 bubbles/second.

the Porter flow meter with A-125-3

 

[Valerio]

Hi to all, I am going to buy a RMA 151 SSV for my 55G and I have found a shop here in Italy that sells it, I need some help please. This shop has the 150 SSV too for the same price, but it doesn't make any sense for my tank, do it?

These flow meters need 1/8" NPT fittings. Since it's not so easy to get 1/8" NPT fittings here (we use mostly BSPT threads), I'd prefer to buy them from the same shop, because some reviews of what I find on Amazon say that they were not NPT actually. I am not sure about the side of the CO2 hose fitting. My CO2 hose is 4/6 mm and I have found these


The former is ok I guess, but the latter maybe is too thin. Considering that Google says 1/8"=3,18mm and 1/4"=6,35mm, should I find a 1/4" OD x 1/8" NPT-M if I want a barbed connector?

 

[GreggZ]

I use 1/8th NPT x 3/16th ID hose barb.

And the 5-50 scale of the RMA151 should be good a 55G.

On my 120G I am a little over 50 cc/min so need a RMA150.

 

[Valerio]

Many thanks Greggz! I have found them, they are made of brass like JayP's picture in the first post

 

[rzn7z7]

I use 1/8th NPT x 3/16th ID hose barb.

And the 5-50 scale of the RMA151 should be good a 55G.

On my 120G I am a little over 50 cc/min so need a RMA150.

Yikes...50 cc/min and you're not gassing your fish?

I have the same flowmeter set to 35 cc/min on a 225G but you've got me thinking....

 

[Naturescapes_Rocco]

I ran my my Dwyer RMA-150 at about 40CC/min on my 140Gal "Many Lessons" tank. There are many factors that affect actual CO2 levels, though, so we can't really compare the level on the meter with what is actually comparable to our tanks.

I like using a lot of surface agitation:


so I also need more CO2/minute. Lots of oxygen and lots of CO2 is how I like it!

My 39gal, running at 40-45ppm CO2, requires about 25CC/min.

 

[JayP]

My 39gal, running at 40-45ppm CO2, requires about 25CC/min.

I think that's where I'm going to start my 49g when I get it reconfigured with the DIY regulator.