Handsets disagree on MV values

MarcLaukien · 2nd September 2007, 23:47

I recently got an upgrade to the new Hammerhand handsets. With the new handsets, the MV readings on the secondary and primary disagree. For example:

100% O2:

Primary: 47/43/49
Secondary: 48/46/47

Dil flush with 21/35:

Primary: 11/9/13
Secondary: 11/11/11

I understand that due to cable length and other factors, the MV readings on the secondary and primary are not expected to be exactly the same. However, in my case, the MV readings are off by quite a large value. What's more worrisome is that the primary handset shows a very large difference between the three cells, while the secondary shows them all very similar.

Has anybody seen this problem?

diverklondike · 3rd September 2007, 01:27

Quote: (Originally Posted by MarcLaukien)

I recently got an upgrade to the new Hammerhand handsets. With the new handsets, the MV readings on the secondary and primary disagree. For example:

100% O2:

Primary: 47/43/49
Secondary: 48/46/47

Dil flush with 21/35:

Primary: 11/9/13
Secondary: 11/11/11

I understand that due to cable length and other factors, the MV readings on the secondary and primary are not expected to be exactly the same. However, in my case, the MV readings are off by quite a large value. What's more worrisome is that the primary handset shows a very large difference between the three cells, while the secondary shows them all very similar.

Has anybody seen this problem?

For what it's worth I don't think that the variancies are that large. I have spoken with Kevin J. about this in the past and have discussed the fact that some variances may exist between the primary and secondary. What you have shown seem within a managable range.

Just my 2 cents...

Mark

***jradomski*** · 3rd September 2007, 03:49

Quote: (Originally Posted by MarcLaukien)

I recently got an upgrade to the new Hammerhand handsets. With the new handsets, the MV readings on the secondary and primary disagree. For example:

100% O2:

Primary: 47/43/49
Secondary: 48/46/47

Dil flush with 21/35:

Primary: 11/9/13
Secondary: 11/11/11

I understand that due to cable length and other factors, the MV readings on the secondary and primary are not expected to be exactly the same. However, in my case, the MV readings are off by quite a large value. What's more worrisome is that the primary handset shows a very large difference between the three cells, while the secondary shows them all very similar.

Has anybody seen this problem?

pretty small variance.. between rounding and the variances within the expected gain of the analog front end (uncalibrated) its well within expected ranges.. If the po2 readings were off by that much then I'd be concerned, but raw uncalibrated output, its fine.. (remember most resisters are in the neighborhood of +/-5% to +/- 10% tolerance) so its expected..

Gilles · 3rd September 2007, 05:24

Quote: (Originally Posted by MarcLaukien)

I recently got an upgrade to the new Hammerhand handsets. With the new handsets, the MV readings on the secondary and primary disagree. For example:

100% O2:

Primary: 47/43/49
Secondary: 48/46/47

Dil flush with 21/35:

Primary: 11/9/13
Secondary: 11/11/11

I'm a little concerned because your readings with 21% O2 should be the following in 99% O2

P:52/43/62
S:52/52/52

Are you sure you have 100% O2? Otherwise your cell linearity may be coming off.

Have you ever done a check at 6m?

G

MarcLaukien · 3rd September 2007, 12:00

Quote: (Originally Posted by jradomski)

pretty small variance.. between rounding and the variances within the expected gain of the analog front end (uncalibrated) its well within expected ranges.. If the po2 readings were off by that much then I'd be concerned, but raw uncalibrated output, its fine.. (remember most resisters are in the neighborhood of +/-5% to +/- 10% tolerance) so its expected..

Thanks for the feedback. With my old cells, the primary and secondary showed nearly the exact same values, so I wasn't sure if the readings I get with the new handsets are within the usual tolerance.

Quote: (Originally Posted by Gilles)

I'm a little concerned because your readings with 21% O2 should be the following in 99% O2

P:52/43/62
S:52/52/52

Are you sure you have 100% O2? Otherwise your cell linearity may be coming off.

Have you ever done a check at 6m?

G

Yes, I'm sure it's 100% O2. After calibrating with 100% O2, and then flushing with Dil several times, I get the following ppO2 values:

Primary: 0.25/0.22/0.26
Secondary: 0.24/0.25/0.23

The handsets are brand new, only tested in the pool so far, so I didn't do any 6m test with the new handsets yet. However, I did test the cells about 2 months ago at 6m with the old handsets. I bought the cells with my Optima about 6 months ago.

Perhaps it's time to change the cells already?

***jradomski*** · 3rd September 2007, 12:49

Quote: (Originally Posted by MarcLaukien)

Thanks for the feedback. With my old cells, the primary and secondary showed nearly the exact same values, so I wasn't sure if the readings I get with the new handsets are within the usual tolerance.

Yes, I'm sure it's 100% O2. After calibrating with 100% O2, and then flushing with Dil several times, I get the following ppO2 values:

Primary: 0.25/0.22/0.26
Secondary: 0.24/0.25/0.23

The handsets are brand new, only tested in the pool so far, so I didn't do any 6m test with the new handsets yet. However, I did test the cells about 2 months ago at 6m with the old handsets. I bought the cells with my Optima about 6 months ago.

Perhaps it's time to change the cells already?

judging by the po2 values and mv readings and assuming its a really good flush.. the cells are no longer linear.. They are probably ok for diving aroun the cal point 1.0 but I would trust them anything higher..

The variation between the primary and secondary is ok.. I would make sure that you check that the is no "extra" pressure in the loop.. Follow the instructions for letting the cells sit n o2 for a period of time and watch that the mv values don't decay..

also Its possible that without a true 100% in the loop, moving the rig or pressing on the cl in any way can move gas around the loop and cal also acount for a discrepency between the 2 handsets..

Its best to place the rig in w way that you can operate the cells without moving gas around the loop..

MarcLaukien · 3rd September 2007, 13:03

Quote: (Originally Posted by jradomski)

judging by the po2 values and mv readings and assuming its a really good flush.. the cells are no longer linear.. They are probably ok for diving aroun the cal point 1.0 but I would trust them anything higher..

The variation between the primary and secondary is ok.. I would make sure that you check that the is no "extra" pressure in the loop.. Follow the instructions for letting the cells sit n o2 for a period of time and watch that the mv values don't decay..

also Its possible that without a true 100% in the loop, moving the rig or pressing on the cl in any way can move gas around the loop and cal also acount for a discrepency between the 2 handsets..

Its best to place the rig in w way that you can operate the cells without moving gas around the loop..

Thanks for the advice. I did let the rig sit for awhile after the O2 flush, and didn't touch the loop during calibration or when reading the MV values for the two handsets. I did this twice, to double-check that my measurements are indeed correct. Once I did a dil flush after calibration, and before that I simply let the cells sit on air after calibration. The readings were more or less the same for both tests.

So I guess it's time for new cells! (Although the ones I have are only six or seven months old...)

**trob09** · 3rd September 2007, 13:12

Are these the new Delrin handsets? I ask because I had sent Kevin a note on Saturday asking about similar behavior from my new handsets.

Flush O2 & get 48 - 52 mv, calibrate
Remove O2 Source (I have a meg & use the head calibration kit) watch MV drop to 9-11 range. PO2 in air? .21/.25/.23 Move wires around (i.e. plug wire for cell 1 into cell 3) and still get .21/.25/.23 put in different cells (some new, some old) and still get .21/.25/.23

Put the same cells in my spare head with metal handsets - get .21/.20/.21.

I haven't heard back from Kevin (it's a holiday weekend and all), but I'm pretty confident that it's not the cell's non-linear performance.

MarcLaukien · 3rd September 2007, 13:18

Quote: (Originally Posted by trob09)

Are these the new Delrin handsets? I ask because I had sent Kevin a note on Saturday asking about similar behavior from my new handsets.

Yes, this is with the new Delrin handsets.

Quote: (Originally Posted by trob09)

Flush O2 & get 48 - 52 mv, calibrate
Remove O2 Source (I have a meg & use the head calibration kit) watch MV drop to 9-11 range. PO2 in air? .25/.23/.21 Move wires around (i.e. plug wire for cell 1 into cell 3) and still get .25/.23/.21 put in different cells (new or old) and still get .25/.23./21

I didn't try this test yet. Sounds very strange! Do you only see this with the primary handset, or with both?[/quote]

Quote: (Originally Posted by trob09)

Put the same cells in my metal handset head - get .21/.20/.21.

I haven't heard back from Kevin (it's a holiday weekend and all), but I'm pretty confident that it's not the cell's non-linear performance.

Please let me know what you find out once you hear from Kevin.

**trob09** · 3rd September 2007, 13:21

Quote: (Originally Posted by MarcLaukien)

I didn't try this test yet. Sounds very strange! Do you only see this with the primary handset, or with both?

Both. In my note to Kevin I suggested that it was a software thing. As I say, I am pretty confident that it's not the cells as I got the exact same behavior from 3 sets of cells.

2nd September 2007, 23:47	#1 (permalink)
MarcLaukien Custom Title Allowed! Current Rebreather/s: Other CCR Other Rebreather/s: Optima Other CCR Join Date: Dec 2006 Location: South East Florida Posts: 202	Handsets disagree on MV values I recently got an upgrade to the new Hammerhand handsets. With the new handsets, the MV readings on the secondary and primary disagree. For example: 100% O2: Primary: 47/43/49 Secondary: 48/46/47 Dil flush with 21/35: Primary: 11/9/13 Secondary: 11/11/11 I understand that due to cable length and other factors, the MV readings on the secondary and primary are not expected to be exactly the same. However, in my case, the MV readings are off by quite a large value. What's more worrisome is that the primary handset shows a very large difference between the three cells, while the secondary shows them all very similar. Has anybody seen this problem?
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3rd September 2007, 01:27	#2 (permalink)
diverklondike Just one of the Peasants Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Inspiration Classic Other CCR Join Date: Oct 2005 Location: Delaware, USA Posts: 1,611	Re: Handsets disagree on MV values Quote: (Originally Posted by MarcLaukien) I recently got an upgrade to the new Hammerhand handsets. With the new handsets, the MV readings on the secondary and primary disagree. For example: 100% O2: Primary: 47/43/49 Secondary: 48/46/47 Dil flush with 21/35: Primary: 11/9/13 Secondary: 11/11/11 I understand that due to cable length and other factors, the MV readings on the secondary and primary are not expected to be exactly the same. However, in my case, the MV readings are off by quite a large value. What's more worrisome is that the primary handset shows a very large difference between the three cells, while the secondary shows them all very similar. Has anybody seen this problem? For what it's worth I don't think that the variancies are that large. I have spoken with Kevin J. about this in the past and have discussed the fact that some variances may exist between the primary and secondary. What you have shown seem within a managable range. Just my 2 cents... Mark
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3rd September 2007, 03:49	#3 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Home Build Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Home Build Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,001	Re: Handsets disagree on MV values Quote: (Originally Posted by MarcLaukien) I recently got an upgrade to the new Hammerhand handsets. With the new handsets, the MV readings on the secondary and primary disagree. For example: 100% O2: Primary: 47/43/49 Secondary: 48/46/47 Dil flush with 21/35: Primary: 11/9/13 Secondary: 11/11/11 I understand that due to cable length and other factors, the MV readings on the secondary and primary are not expected to be exactly the same. However, in my case, the MV readings are off by quite a large value. What's more worrisome is that the primary handset shows a very large difference between the three cells, while the secondary shows them all very similar. Has anybody seen this problem? pretty small variance.. between rounding and the variances within the expected gain of the analog front end (uncalibrated) its well within expected ranges.. If the po2 readings were off by that much then I'd be concerned, but raw uncalibrated output, its fine.. (remember most resisters are in the neighborhood of +/-5% to +/- 10% tolerance) so its expected.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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3rd September 2007, 05:24	#4 (permalink)
Gilles Worship the feminine Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: Den Haag (Netherlands) Posts: 762	Re: Handsets disagree on MV values Quote: (Originally Posted by MarcLaukien) I recently got an upgrade to the new Hammerhand handsets. With the new handsets, the MV readings on the secondary and primary disagree. For example: 100% O2: Primary: 47/43/49 Secondary: 48/46/47 Dil flush with 21/35: Primary: 11/9/13 Secondary: 11/11/11 I'm a little concerned because your readings with 21% O2 should be the following in 99% O2 P:52/43/62 S:52/52/52 Are you sure you have 100% O2? Otherwise your cell linearity may be coming off. Have you ever done a check at 6m? G __________________ Gilles http://www.dirrebreather.com Last edited by Gilles : 3rd September 2007 at 12:30.
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3rd September 2007, 12:00	#5 (permalink)
MarcLaukien Custom Title Allowed! Current Rebreather/s: Other CCR Other Rebreather/s: Optima Other CCR Join Date: Dec 2006 Location: South East Florida Posts: 202	Re: Handsets disagree on MV values Quote: (Originally Posted by jradomski) pretty small variance.. between rounding and the variances within the expected gain of the analog front end (uncalibrated) its well within expected ranges.. If the po2 readings were off by that much then I'd be concerned, but raw uncalibrated output, its fine.. (remember most resisters are in the neighborhood of +/-5% to +/- 10% tolerance) so its expected.. Thanks for the feedback. With my old cells, the primary and secondary showed nearly the exact same values, so I wasn't sure if the readings I get with the new handsets are within the usual tolerance. Quote: (Originally Posted by Gilles) I'm a little concerned because your readings with 21% O2 should be the following in 99% O2 P:52/43/62 S:52/52/52 Are you sure you have 100% O2? Otherwise your cell linearity may be coming off. Have you ever done a check at 6m? G Yes, I'm sure it's 100% O2. After calibrating with 100% O2, and then flushing with Dil several times, I get the following ppO2 values: Primary: 0.25/0.22/0.26 Secondary: 0.24/0.25/0.23 The handsets are brand new, only tested in the pool so far, so I didn't do any 6m test with the new handsets yet. However, I did test the cells about 2 months ago at 6m with the old handsets. I bought the cells with my Optima about 6 months ago. Perhaps it's time to change the cells already?
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3rd September 2007, 12:49	#6 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Home Build Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Home Build Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,001	Re: Handsets disagree on MV values Quote: (Originally Posted by MarcLaukien) Thanks for the feedback. With my old cells, the primary and secondary showed nearly the exact same values, so I wasn't sure if the readings I get with the new handsets are within the usual tolerance. Yes, I'm sure it's 100% O2. After calibrating with 100% O2, and then flushing with Dil several times, I get the following ppO2 values: Primary: 0.25/0.22/0.26 Secondary: 0.24/0.25/0.23 The handsets are brand new, only tested in the pool so far, so I didn't do any 6m test with the new handsets yet. However, I did test the cells about 2 months ago at 6m with the old handsets. I bought the cells with my Optima about 6 months ago. Perhaps it's time to change the cells already? judging by the po2 values and mv readings and assuming its a really good flush.. the cells are no longer linear.. They are probably ok for diving aroun the cal point 1.0 but I would trust them anything higher.. The variation between the primary and secondary is ok.. I would make sure that you check that the is no "extra" pressure in the loop.. Follow the instructions for letting the cells sit n o2 for a period of time and watch that the mv values don't decay.. also Its possible that without a true 100% in the loop, moving the rig or pressing on the cl in any way can move gas around the loop and cal also acount for a discrepency between the 2 handsets.. Its best to place the rig in w way that you can operate the cells without moving gas around the loop.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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3rd September 2007, 13:03	#7 (permalink)
MarcLaukien Custom Title Allowed! Current Rebreather/s: Other CCR Other Rebreather/s: Optima Other CCR Join Date: Dec 2006 Location: South East Florida Posts: 202	Re: Handsets disagree on MV values Quote: (Originally Posted by jradomski) judging by the po2 values and mv readings and assuming its a really good flush.. the cells are no longer linear.. They are probably ok for diving aroun the cal point 1.0 but I would trust them anything higher.. The variation between the primary and secondary is ok.. I would make sure that you check that the is no "extra" pressure in the loop.. Follow the instructions for letting the cells sit n o2 for a period of time and watch that the mv values don't decay.. also Its possible that without a true 100% in the loop, moving the rig or pressing on the cl in any way can move gas around the loop and cal also acount for a discrepency between the 2 handsets.. Its best to place the rig in w way that you can operate the cells without moving gas around the loop.. Thanks for the advice. I did let the rig sit for awhile after the O2 flush, and didn't touch the loop during calibration or when reading the MV values for the two handsets. I did this twice, to double-check that my measurements are indeed correct. Once I did a dil flush after calibration, and before that I simply let the cells sit on air after calibration. The readings were more or less the same for both tests. So I guess it's time for new cells! (Although the ones I have are only six or seven months old...)
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3rd September 2007, 13:12	#8 (permalink)
trob09 . Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Feb 2005 Posts: 699	Re: Handsets disagree on MV values Are these the new Delrin handsets? I ask because I had sent Kevin a note on Saturday asking about similar behavior from my new handsets. Flush O2 & get 48 - 52 mv, calibrate Remove O2 Source (I have a meg & use the head calibration kit) watch MV drop to 9-11 range. PO2 in air? .21/.25/.23 Move wires around (i.e. plug wire for cell 1 into cell 3) and still get .21/.25/.23 put in different cells (some new, some old) and still get .21/.25/.23 Put the same cells in my spare head with metal handsets - get .21/.20/.21. I haven't heard back from Kevin (it's a holiday weekend and all), but I'm pretty confident that it's not the cell's non-linear performance. Last edited by trob09 : 3rd September 2007 at 13:50. Reason: fixed the order of the PO2 reading.
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3rd September 2007, 13:18	#9 (permalink)
MarcLaukien Custom Title Allowed! Current Rebreather/s: Other CCR Other Rebreather/s: Optima Other CCR Join Date: Dec 2006 Location: South East Florida Posts: 202	Re: Handsets disagree on MV values Quote: (Originally Posted by trob09) Are these the new Delrin handsets? I ask because I had sent Kevin a note on Saturday asking about similar behavior from my new handsets. Yes, this is with the new Delrin handsets. Quote: (Originally Posted by trob09) Flush O2 & get 48 - 52 mv, calibrate Remove O2 Source (I have a meg & use the head calibration kit) watch MV drop to 9-11 range. PO2 in air? .25/.23/.21 Move wires around (i.e. plug wire for cell 1 into cell 3) and still get .25/.23/.21 put in different cells (new or old) and still get .25/.23./21 I didn't try this test yet. Sounds very strange! Do you only see this with the primary handset, or with both?[/quote] Quote: (Originally Posted by trob09) Put the same cells in my metal handset head - get .21/.20/.21. I haven't heard back from Kevin (it's a holiday weekend and all), but I'm pretty confident that it's not the cell's non-linear performance. Please let me know what you find out once you hear from Kevin.
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3rd September 2007, 13:21	#10 (permalink)
trob09 . Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Feb 2005 Posts: 699	Re: Handsets disagree on MV values Quote: (Originally Posted by MarcLaukien) I didn't try this test yet. Sounds very strange! Do you only see this with the primary handset, or with both? Both. In my note to Kevin I suggested that it was a software thing. As I say, I am pretty confident that it's not the cells as I got the exact same behavior from 3 sets of cells.
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