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Thread: Welding day are over
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27th Mar 2022, 04:33 PM #16Philomath in training
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27th Mar 2022, 08:57 PM #17China
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Thanks for offer Michael seems like I am fully catered for when the need arises.
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20th Apr 2022, 07:10 PM #18China
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I had my first post surgery visit today the more experienced nurse said I can use a 240volt domestic machine but not a 3ph unit and only make short runs apparently long runs will be seen as problem and I will receive a shock
she said I will only make the mistake once. I should still keep well clear of magnetic chucks etc.
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20th Apr 2022, 07:19 PM #19Member: Blue and white apron brigade
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20th Apr 2022, 08:54 PM #20Senior Member
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20th Apr 2022, 09:06 PM #21Most Valued Member
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Took my mother to a doctor because I was pretty sure she had a stroke. Doctor said no. Nurse disagreed and asked doctor to get tests done. Guess who had the correct diagnosis.
Nev.
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20th Apr 2022, 09:44 PM #22China
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Not an ordinary nurse she is a pacemaker CRT-D specialist nurse and has been practicing this aspect of nursing for 15 years.
BobL hopefully I don't find out, apparently the first time is a bit a a shock (excuse the pun).
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25th Apr 2022, 10:15 AM #23Senior Member
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A lot will depend on the defibrillator programming.
Implanted defibrillators work by:
Continuously watching the electricity in the heart.
Watching for a rapid heart rate over a certain threshold, e.g. 170 beats per minute.
Then there will be a time threshold, e.g. 10 seconds.
The defibrillator will also try and work out if it is a supraventricular tachycardia (SVT) which is not life threatening, or if it is ventricular tachycardia (VT) or ventricular fibrillation (VF) which are life threatening and the reason for the defib.
If the tachycardia is > the rate threshold and goes on for > the time threshold (and is not classified as an SVT) then the defibrillator will commence tachycardia therapies.
Tachycardia therapy will depend on the programming / heart rate. There are different zones.
Usually, the first zone (conditional shock zone) will start with Antitachycardia pacing (ATP) - this paces (stimulates) the heart at a speed faster than the tachycardia. If ATP does not work and tachycardia continues long enough, the device will likely be programmed to deliver shocks.
A shock zone (VF zone) will be set up for faster heart rates and will go straight to shocks.
Welding may look like VF (very dangerous rhythm) to the device.
The faster the detected heart rate, the shorter the time threshold usually is. The shock zone / VF zone may deliver a shock after a few seconds - depends on programming.
ICD-tracings-of-near-field-RVtip-to-RVring-and-far-field-Can-to-RVcoil-EGM-during.png
That image is an example of EMI on a defibrillator. These are tracings from a defibrillator - what the defib is seeing.
This one is 60hz AC noise. On panel A (top panel) the duration of noise was short enough that the defib did not perform any therapy.
When the EMI is present, the device cannot see the heart's electricity, it is drowned out by the EMI.
On the lower panel B, the defibrillator delivered a shock (where it says 35.2 J in small letters - 35.2 joules).
The little letters along the bottom of each panel tell you what the device is seeing. V S = ventricular sensed. The numbers are the cycle length (the time in milliseconds between detected electrical signals). (60,000/cycle length in msec = heart rate in beats per minute).
The EMI stops in panel B after the defib shocks the patient, because the patient stopped touching the electrical outlet.
So whether EMI / welding will cause issues depends on:
How much EMI is produced
How fast it makes the defib think the heart rate it
How long the EMI is present
A review and study of EMI on pacemakers:
https://core.ac.uk/download/pdf/32425226.pdf
You can somewhat reduce EMI on the defib by:
Increasing distance between the defib and the source of noise (arc, welding cables and welder)
Twisting the welding cables together may help
Note the above all is about defibrillators - pacemaker function is different.
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25th Apr 2022, 11:25 PM #24
This is really helpful information (for the informed)! Thank you very much! I could well be a candidate down the road, and this kind of detailed info is really helpful to decide if it's worth the risk or not. Once you know enough about how the device is programmed, you can then set up some EMI measuring or monitoring devices to determine what activities might falsely set off a defib. I'm a little concerned about VFDs with inadequate shielding for example. And I doubt that any cardiologists have a sense of what they are, do or how they might trigger false VF signals in their sensing circuits....
Cheers, Joe
retired - less energy, more time to contemplate projects and more shed time....
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26th Apr 2022, 10:26 AM #25China
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Great information in my case the programing must be considered safe to attempt welding (domestic). The nurse I was discussing it with is the one who does the programing and makes any adjustment that may or may not be required, I go back every 7 months, from now on for download any any modification .
I do not think she would have suggested it was safe unless she was happy with it, I will the first to know.
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28th Apr 2022, 05:41 PM #26Most Valued Member
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Sorry to hear about the need for the heart gizmo china, it is a bummer this getting old caper.
I think that it might be helpful if you contacted the manufacturer of the implant to find out exactly what they recommend and/or what they know or don't know....for instance would DC be safer than AC or vice versa.
I just did a little search and this mob say you can weld up to 160 amps.... I reckon that would allow you to keep welding, how often would you really need more amps than that?
I think you need to find out and need to know what the manufacturer of your device recommends as the nurse may be generalizing and not giving you info specific to your device.
This is the info that I found from a mob called Medtronic..... follow the link for more info.
https://www.medtronic.com/us-en/pati...s.html#welding
Q: What if I may need to use a welder?
A: It is recommended you avoid using welding currents above 160 amps. Follow the safety precautions below to minimize the risk of interfering with your heart device while welding with currents under 160 amps.
Welding Safety Precautions:
- Limit welding to currents less than 160 amps.
- Work in a dry area with dry gloves and shoes.
- Maintain a 2-foot (60 centimeter) distance between the welding arc and heart device.
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30th Apr 2022, 04:46 AM #27China
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Yeh thanks shed, my device is a St. Jude Medical ( Now Abbott laboratories) apparently the world leaders in this field, their advice is much the same, however they also recommend I speak with My doctors.
I have a job coming up and I will report back if it is a shocking experience or not.
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30th Apr 2022, 11:17 AM #28Most Valued Member
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Maybe have someone with you when you weld for the first few times?
Simon
Sent from a galaxy far far awayGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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30th Apr 2022, 02:56 PM #29Most Valued Member
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So they cover their rs's by telling you to speak to your doctor......hahaha....really? How many doctors know anything about electromagnetic radiation from welding....close to zero is my bet..
I think maintaining the 2 foot distance from the weld might be a challenge but surely this would be the distance at the under 160amp welding and the distance would reduce with a reduction in amps. BobL mentioned earlier about the possibility of shielding and that would probably be worth thinking about, I had in the past seen flywire supposedly used for that but did not find anything on it, here are 2 vids one with mesh and one with metal sheet shielding that might give you some clues.
https://www.youtube.com/watch?v=Lg_aUOSLuRo
http://realdocumentaries.com/defeating-microwave-weapons/
had some dramas with these links????
Also does your hand/arm conduct electromagnetic radiation? If so maybe an earthed wrist strap?
I also think it would be a good idea to have a life saver standing by.........make sure she is good looking tho and maybe you could do some practice runsLast edited by shedhappens; 30th Apr 2022 at 04:24 PM. Reason: fixed links
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30th Apr 2022, 03:21 PM #30Most Valued Member
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If it was my heart I wouldn't be going near a welder. Might be a good time to reacquaint yourself with oxy/acetylene.
Chris
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