[PSUBS-MAILIST] Ammeter / PLC Question

Tue Jan 16 16:19:38 EST 2018

Re-thinking the ammeter question.
I had suggested using a shunt for measuring amps & Cliff is using some 
expensive unit based on measuring the electric field around the wire.
With a PLC could I not just buy an inexpensive Voltage sensor with 4-20Ma output
& an inexpensive resistance sensor with  4-20Ma output & calculate the Amps
in the PLC program based on these 2 numbers (V/R=A)
Does anyone know of a suitable Voltage & resistance sensor, or is this not
the best way to do it.
Cheers Alan

Sent from my iPad

> On 10/01/2018, at 2:17 PM, Steve McQueen via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Rick, I am making the same decision currently.  I am leaning toward using a 300A ammeter to monitor total current draw in my 12V DC system (see attached example and working sketch).
> I am going to use the “circular loop” style tap (hall effect sensor) mainly because the point I am monitoring is 2/0 AWG.  Not an easy thing to splice into.
>  
> There might be some sensitivity/accuracy issues associated with the exact location of the wire within the sensor but I not concerned with high accuracy as much as a repeatable reference. I would guess you could arrange/install it such as to minimize this positional concern.
> I am not sure about the sensor being affected by “touching” the hull but I would just mount it such that it avoids that contact.
>  
> Personally I am not monitoring individual thruster circuits but am relying on breakers to indicate issues.
>  
> I am trying to keep things simple in my K-250.
>  
> Steve
>  
> From: Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org] On Behalf Of Rick Patton via Personal_Submersibles
> Sent: Tuesday, January 9, 2018 7:49 PM
> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] At Home O2 Cleaning Process
>  
> Can't get into my contacts page to send a new thread rite now (I hate computers) so gonna tag this thread for something different, sorry...
>  
> I am getting ready to purchase my amp and volt meters for the 12V and 36V banks and had a few questions. There are two ways that I know of to tap into a line to measure current. One is a direct splice and the other is using a meter that has a DROK/necklace that encircles the wire you want to measure. Would like to know the best way to go on those types. It would be a lot easier to use a necklace type to minimize the amount of splices that I have to make and moisture proof but a friend of mine said that there is a minute difference in readings if the wire is up against the side of the necklace rather than in the middle and I also wounder if having the necklace up against the steel hull would mess with the readings?  I also assume that I should have a separate amp meter for each of my three thrusters? 
> Thanks 
> Rick
>  
> On Mon, Jan 8, 2018 at 6:08 AM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> Cliff,   I ordered those items !    I'm going to get another style flow meter as well .  How accurate is that acrylic flow meter? 
>  
> Brian
>  
> 
> 
> --- personal_submersibles at psubs.org wrote:
> 
> From: Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org>
> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] At Home O2 Cleaning Process
> Date: Sun, 7 Jan 2018 14:21:18 -0600
> 
> Brian, in my (Air Monitoring, Oxygen Control) AMOC system, I use a Porter 201-FSVP mass controller.  Ebay has these units for sell all the time at pennies on the dollar. These unit will both measure the mass rate of the gas in SLPM and also control it. There are two 0-5VDC control signals for the unit.  For this partuclar unit which has a 0-10 SLPM span, if you give the controller pin 5V, then it will pass 10 SLPM if you give it 0V, it will pass zero SLPM.  The other singal is an analog voltage output signal again 5Vdc for full span, would be a measured 10 SLPM and a zero signal means it is reading zero mass flowrate of gas.  https://www.ebay.com/itm/Porter-201-AFASVPAA-Mass-Flow-Controller-10-SLPM-760-Torr-MFC/232159305887?hash=item360dc5e09f:g:BTAAAOSwmrlUrcG1 is a link to ebay for a unit very close to this.  Porter (Parker) make a ton of different  controller for different rates and different gasses.  The controller as a 9 pin blade style connector that is used widely in the medical industry.  The documentation on these meters is excellent and you can download it https://www.parker.com/literature/MFM%20&%20MFC%20(D-Conn.)%20(FM-898%20Rev.%20E).pdf .  The manual calls out the spec for the connector.  I use this unit with a PLC but single it is analog voltage signals, you could control with potentiometer off a 5VDC source.  Likewise you could use an analog display that would take a 0-5VDC signal if you wanted. I have found these units to be very reliable.  In my Life support system module, I use a Swagelok a Vernier needle valve model SS-SS4-VH as a bypass around this controller for manual O2 bleed control.  As a backup, I use a variable area meter like https://www.amazon.com/dp/B019YS4PSG/ref=asc_df_B019YS4PSG5328541/?tag=hyprod-20&creative=395033&creativeASIN=B019YS4PSG&linkCode=df0&hvadid=198097951144&hvpos=1o1&hvnetw=g&hvrand=6957636125906653374&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9027968&hvtargid=pla-542207540152 .  
>  
> Cliff
>  
> On Sat, Jan 6, 2018 at 1:56 PM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> I just talked to my local dive shop and they will fill O2 no questions asked .  They say they do it all the time.  I'm thinking of getting set up with a package from DAN  Here:
>  
>  
> https://www.diversalertnetwork.org/dive-store/?catno=9
>  
>  
> It seems to be somewhat problematic getting the right all the components but getting one of these units from the DAN website might make things easier as far as getting bottles filled and so forth.  The delivery system on these units I don't think has enough fine tuning ability however.  Does anyone have a good flow meter to recommend?  Is there an analog type with a little ball that floats up and down? 
>  
>  
> 
> Brian
>  
> 
> 
> --- personal_submersibles at psubs.org wrote:
> 
> From: "Sean T. Stevenson via Personal_Submersibles" <personal_submersibles at psubs.org>
> To: personal_submersibles at psubs.org
> Subject: Re: [PSUBS-MAILIST] At Home O2 Cleaning Process
> Date: Sat, 06 Jan 2018 13:58:20 -0500
> 
> I use dilute acetic acid to remove any existing corrosion, and then a non-solvent hydrocarbon-free detergent solution to clean, followed by a freshwater rinse, and possibly another cycle using a separate clean batch of detergent solution. Use dedicated brushes for each bin. A lint-free cloth should come back clean, and the cleaner solution and rinse water should both produce no fluorescence under UV (black light). Dry passively, or with filtered air or bottled nitrogen so as not to reintroduce any contaminants. Any subsequent lubrication or assembly with lubricated soft parts should be done with oxygen compatible lubricants (i.e. Christolube).
> 
> Sean
> 
> Sent from ProtonMail mobile
> 
> 
> 
> -------- Original Message --------
> On Jan 6, 2018, 09:23, Steve McQueen via Personal_Submersibles < personal_submersibles at psubs.org> wrote:
>  
> All, I am working on cleaning some parts/pieces for O2 service on my K-250. I am buying most items “pre-cleaned” such as: Tank w/Valve, First Stage Regulator, Thru Hull Isolation Valve, Flow Regulator.
>  
> However, I will have some parts & pieces (mainly misc. adaptors and ¼ SS tubing) I may still need to clean.
> I know an “at home” process will fall short but looking to create/document a procedure anyway.
> 
> ·        I am using ASTM G93, "Standard Practice for Cleaning Methods and Cleanliness Levels for Material and Equipment Used in Oxygen-Enriched Environments" as the standard.
> 
> ·         
> 
> ·        Maybe someone already has a procedure (or opinion) they want to share?
> 
> Steve
> 
>  
> 
> ·         
> 
>  
> ·        I am using ASTM G93, "Standard Practice for Cleaning Methods and Cleanliness Levels for Material and Equipment Used in Oxygen-Enriched Environments" as the standard.  I know an “at home” process will fall short but looking to create/document a procedure anyway.
> 
> ·         
> 
>  
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>  
> <AMP_Volt Meter.PNG>
> <High Current Distribution Circuit.docx>
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