Results 1 to 9 of 9

Thread: Want Gas Pressure Sensor

  1. #1
    Frequent Visitor bigjim's Avatar
    Join Date
    Oct 2014
    Location
    Carpentersville, Il
    Posts
    367

    Want Gas Pressure Sensor

    Like many others I have a CA reactor that relies upon a CO2 tank to work. I use a PH probe to control the CO2 and monitor my CA reactor. What would be really nice would be a pressure sensor that could be attached between the tank valve and regulator that could be programmed in Apex to send notifications when the pressure in the tank drops below a specified level. This would give us time to replace a tank that is about to go empty before the tank is empty. The last time my CO2 tank went empty was on a Saturday afternoon. By then the local supplier where I get my CO2 from was closed for the weekend. The meant I had to wait to Monday afternoon to get a fresh tank of CO2 to run my reactor. Being able to monitor the amount of gas in the tank would be especially helpful when going out of town for a week's vacation.

  2. #2
    Frequent Visitor
    Join Date
    Mar 2016
    Location
    canada
    Posts
    93
    Ya that.would be awesome

    Sent from my SM-G930W8 using Tapatalk

  3. #3
    Frequent Visitor
    Join Date
    Jul 2015
    Location
    Illinois -6 Time Zone
    Posts
    68
    I don't run CA reactor but you could probably 1. get a pneumatic pressure switch and use a BOB circuit that will open or close circuit to have Apex alarm and text you. 2. Get a small spare tank as backup

  4. #4
    Frequent Contributor zombie's Avatar
    Join Date
    Dec 2013
    Location
    Denver, CO
    Posts
    13,176
    That is a really big expense for something that can fairly easily be done with programming alone.

    Two alarms can tell you if there is something wrong with the flow and if the tank is getting low but not out by using the following process.


    1. Set your logging interval to 1 min temporarily so you can better log your reactor solenoid.

    2. After 1 week has past record the lengths of time your solenoid was on and the times your solenoid was off. This must 've with clear flow and a tank at least half full.

    3. Determine the min, max, and average times the solenoid was on and off.


    Then you need to make a couple virtual outlets based on the numbers you gathered.


    For a flow alarm take the average ON time, multiply by the larger of 2 times the average or 1.1 times the max. I am assuming this number is 30 minutes in the example below and CaRx is the name of your solenoid outlet.

    CaRxFlowAl (virtual outlet)
    Set OFF
    If Outlet CaRx = ON Then ON
    Defer 030:00 Then ON


    For a low tank alarm take the average OFF time, multiply by the larger of 1.5 times the average or 1.1 times the max. I am assuming this number is 40 minutes in the example below and CaRx is the name of your solenoid outlet.

    Co2Low (virtual outlet)
    Set OFF
    If Outlet CaRx = OFF Then ON
    Defer 040:00 Then ON



    You might be an engineer if...You have no life and can prove it mathematically.

  5. #5
    Frequent Visitor
    Join Date
    Nov 2013
    Location
    Wilmington, DE
    Posts
    163
    Zombie I believe I am following you for the most part above, but I am wondering it this would really work as you mean it to if the CO2 was tuned the way I have run calcium reactors in the past. (currently not running any, but have some standing by)


    I typically had reactors setup so that the CO2 feed rarely went off (solenoid rarely closed). It may have gone off 1-3 times per day. Basically using the needle valve I restricted the gas flow (bubble rate) to be very close to what was required to have the regulator on all the time. This way if the solenoid got stuck on or the Apex failed to turn it off (or I messed up my coding) then I wouldn't quickly melt all my reactor media and cause issues in the tank. Doing things this way also should help the solenoid last much longer as I believe most wear out after a certain number of on/off cycles and are not bothered by being on most of the time.(this is what I was told by at least one manufacturer)
    I am thinking your code above wouldn’t work with infrequent and short off cycles.

  6. #6
    Frequent Contributor zombie's Avatar
    Join Date
    Dec 2013
    Location
    Denver, CO
    Posts
    13,176
    Quote Originally Posted by TerraReef View Post
    Zombie I believe I am following you for the most part above, but I am wondering it this would really work as you mean it to if the CO2 was tuned the way I have run calcium reactors in the past. (currently not running any, but have some standing by)


    I typically had reactors setup so that the CO2 feed rarely went off (solenoid rarely closed). It may have gone off 1-3 times per day. Basically using the needle valve I restricted the gas flow (bubble rate) to be very close to what was required to have the regulator on all the time. This way if the solenoid got stuck on or the Apex failed to turn it off (or I messed up my coding) then I wouldn't quickly melt all my reactor media and cause issues in the tank. Doing things this way also should help the solenoid last much longer as I believe most wear out after a certain number of on/off cycles and are not bothered by being on most of the time.(this is what I was told by at least one manufacturer)
    I am thinking your code above wouldn’t work with infrequent and short off cycles.
    You can still do long cycles, but you can't go extremely long with that approach. 4 cycles a day is about the longest you can go with this approach reliably. I think I shot for hourly with mine (haven't run a reactor for a couple years) because I kept pH at the high end of the recommended range. With mine hourly cycles would not melt if locked on, but allowed be to adjust pH rather than output flow to adjust alkalinity so my girlfriend didn't have to adjust knobs if it was out while I was on a work trip.

    Sent from my SM-G965U using Tapatalk

  7. #7
    Frequent Visitor
    Join Date
    May 2014
    Location
    Portugal
    Posts
    389
    Well,

    If I understand correctly from what I am reading the high pressure inside the tank will always be the same during full and empty CO2 bottles.
    From what I am reading the only way to measure the amount of CO2 inside the bottle is to weight it.

    Took this from a beer forum: https://www.homebrewtalk.com/forum/t...re-psi.265611/

    All the best,
    Rui

  8. #8
    Frequent Contributor zombie's Avatar
    Join Date
    Dec 2013
    Location
    Denver, CO
    Posts
    13,176
    Quote Originally Posted by Rui Manuel Gaspar View Post
    Well,

    If I understand correctly from what I am reading the high pressure inside the tank will always be the same during full and empty CO2 bottles.
    From what I am reading the only way to measure the amount of CO2 inside the bottle is to weight it.

    Took this from a beer forum: https://www.homebrewtalk.com/forum/t...re-psi.265611/

    All the best,
    Rui
    That post you pulled is incorrect. The output pressure of the tank shown on a double gauge regulator changes significantly on a half full vs completely full container. The output pressure of the regulator stays pretty consistent until the pressure of the tank has gotten pretty low. Once the tank pressure reaches a certain point, the regulator pressure also starts to drop. In my experience, once there is about 10% liquid remaining (with an aquarium plants doser) there is enough loss in output regulator pressure to change the cycling characteristics in the reactor.

    Sent from my SM-G965U using Tapatalk

  9. #9
    Frequent Visitor bigjim's Avatar
    Join Date
    Oct 2014
    Location
    Carpentersville, Il
    Posts
    367
    Quote Originally Posted by zombie View Post
    That post you pulled is incorrect. The output pressure of the tank shown on a double gauge regulator changes significantly on a half full vs completely full container. The output pressure of the regulator stays pretty consistent until the pressure of the tank has gotten pretty low. Once the tank pressure reaches a certain point, the regulator pressure also starts to drop. In my experience, once there is about 10% liquid remaining (with an aquarium plants doser) there is enough loss in output regulator pressure to change the cycling characteristics in the reactor.

    Sent from my SM-G965U using Tapatalk
    Zombie is correct. If I remember correctly from Chem103: PV=nRT. If n (number of gas moles) drops, temp doesn't change, R is a constant and the tank volume doesn't change then the pressure has to have a corresponding drop.

Similar Threads

  1. Pressure Switch
    By rinconmike in forum DIY
    Replies: 1
    Last Post: 02-01-2020, 08:57
  2. Question: Apex Pressure Sensor Lighting
    By ResolutionDP in forum DIY
    Replies: 7
    Last Post: 01-16-2019, 14:23
  3. Gas Water Heater Titanium Heat Exchange
    By aaronfelt in forum DIY
    Replies: 5
    Last Post: 11-24-2018, 18:21
  4. Question: Logging CO2 pressure
    By ryannterror in forum Misc Apex Usage & Programming
    Replies: 18
    Last Post: 06-17-2016, 10:55
  5. Pressure Switch
    By Fasthackem in forum AquaBus Modules, Probes, and Breakout Boxes
    Replies: 9
    Last Post: 04-04-2015, 04:02

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •