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EST Procedures for General Ultrasound #49805
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Lau Yew nen Offline OP
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Lau Yew nen  Offline OP
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Hi fellow BMET
Good day to you all. I would like to get some advice from you all on the Electrical Safety Testing procedures for General Ultrasound Equipments.

Currently, our practice is doing the EST separately according to the numbers of US probes. Meaning that, there is will definitely 1 EST for the main unit (console), and separate EST for each probes, say the unit has 3 US probes, then we have to do EST for 3 US probes separately.

EST for the main unit (Console) depends on the classification and AP types. For instance, IEC601-1 Class I, Type B

As for the probes, the US probes are wrapped by using aluminium foil filled with US gel, and attached with the Grounding probe of EST analyzer. Then EST is carried out by using CL2 and AP type maybe BF or CF depends of the US probe specification. If we have 2 US probes, then we have to do 2 EST for each probes.

We are wondering whether the method that we used is accepted or not. T

Therefore we are looking forward for more feedback as we can have a platform to exchange ideas and knowledge.


Re: EST Procedures for General Ultrasound [Re: Lau Yew nen] #49807
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Geoff Hannis Offline
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Welcome to the forum. smile

There is nothing much wrong with the technique you describe ... as long as you have the time to do all that (ie, test each probe individually). Why are you doing that? And which tests are you applying ... donít tell me it includes "mains on applied parts"?

How many probes have been wrecked in this way, I wonder?

I could also ask:- what about the recorder, monitor, printer ... and anything else hanging off that system?

Perhaps someone else will come on here and give Chapter and Verse about which Standard is applicable to ultrasound units, but in my experience a simple single test to BS-62353 (for example) at the main incoming power cable is usually all that gets done (if that*).

* Let certain service providers challenge that if they wish!

Re: EST Procedures for General Ultrasound [Re: Lau Yew nen] #49811
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Hi Geoff,
Thanks for your prompt respond. The test that we are performing doesn't includes "mains to applied part" as we have already set there is zero "0" AP on the analyzer. What we do is to measure the enclosure leakage current emitted by the US probe during the test.

For those accessories such as monitor, printers, recorders.. we didn't perform the test depending on the tagging of the unit or system.

So, for the test your perform using BS62353, do you include AP test such as Patient Leakage Current, Patient Axillary Leakage Current and etc? I'm sure you didn't right?!? because these tests will perform "mains on AP" in the test sequence.

It's good we can have someone to give a chapter or more for this topic. smile

Last edited by Lau Yew nen; .
Re: EST Procedures for General Ultrasound [Re: Lau Yew nen] #49812
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Hi Geoff
Just a bit curious, I never think of this matter before. What happen if we perform "mains to applied part" test on the US probe? Who knows one day my junior is asking this question? I myself also don't know what is the answer. Thanks in advance.

Re: EST Procedures for General Ultrasound [Re: Lau Yew nen] #49816
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Why not do the full test and then repeat the applied part tests only for each probe?
Or is it an automatic tester where you just press Go and stand back? But I think even these can be set to pause and redo tests.

Bring back the Rigel suitcase tester (model 144??) when you had to manually operate the tests and it would do what you wanted it to do.

Robert

Last edited by RoJo; .

My spelling is not bad. I am typing this on a Medigenic keyboard and I blame that for all my typos.
Re: EST Procedures for General Ultrasound [Re: RoJo] #49818
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Originally Posted By: RoJo
Why not do the full test and then repeat the applied part tests only for each probe?
Or is it an automatic tester where you just press Go and stand back? But I think even these can be set to pause and redo tests.

Bring back the Rigel suitcase tester (model 144??) when you had to manually operate the tests and it would do what you wanted it to do.

Robert


Hi Rojo
Thanks. Now I'm confused, should I do applied part or not? We have Dale 600, QA90 and Bender Unimet. Both manual and auto. But to start with the most basic way, we should learn how to use manual. Mind to explain further by using manual type? How is the set up goes about?

Re: EST Procedures for General Ultrasound [Re: Lau Yew nen] #49820
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Geoff Hannis Offline
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Take a look at 62353. You can download a good introduction here. smile

In case you weren't already aware, there are also some nice articles about electrical safety right here.

Re: EST Procedures for General Ultrasound [Re: Geoff Hannis] #49822
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Originally Posted By: Geoff Hannis

Take a look at 62353. You can download a good introduction here. smile

In case you weren't already aware, there are also some nice articles about electrical safety right here.


Hi Geoff
Thank you. I've downloading the guide for 62353. But we are not using this standard at this moment. We only practising IEC601-1 and IEC61010.

I have read through great articles posted in the website. But want to be sure, if we wanna to perform the EST for general ultrasound, how is the setting up like? Seems like different place will have different set up and idea. Which one is correct?

What will happen if we perform "Mains on applied part" test on US probe? I think about this question all over the whole night but I still cannot figure out what is the correct answer. Please enlighten me.

Re: EST Procedures for General Ultrasound [Re: Lau Yew nen] #49823
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Originally Posted By: Lau Yew nen
What will happen if we perform "Mains on applied part" test on US probe?

You will probably end up damaging those expensive probes (and, possibly, yourself if you're not careful).

No need to loose any more sleep ... just adopt (and follow) 62353 for all your electrical safety testing. That is:- do only what needs to be done. Simplify. smile

Re: EST Procedures for General Ultrasound [Re: Geoff Hannis] #49824
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DaveC in Oz Offline
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Have to agree with Geoff here (oh no, not again) doing a mains on applied part on a US probe is a really bad idea. I would stay well away from doing so.


Thoughts and information provided on this forum are mine and mine alone and do not necessarily reflect the policy of NSW Health. They may also be complete bollocks!!
Re: EST Procedures for General Ultrasound [Re: Geoff Hannis] #49826
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Originally Posted By: Geoff Hannis

Originally Posted By: Lau Yew nen
What will happen if we perform "Mains on applied part" test on US probe?

You will probably end up damaging those expensive probes (and, possibly, yourself if you're not careful).

No need to loose any more sleep ... just adopt (and follow) 62353 for all your electrical safety testing. That is:- do only what needs to be done. Simplify. smile


Hi Geoff
Thanks for your reply. Currently we only use IEC601-1 and IEC61010. I guess the ministry is considering adopting IEC62353 in near future. So we just stick on these 2 standards. Without doubts, IEC62353 is very simple and easy way to go, but we still have to stick to our current standards.

Therefore our practice of measuring enclosure (or touch) leakage current for US probe by using CL2;BF;0AP or CL2;CF;0AP (by immersed the probe with gel and wrap it using aluminium foil and attaching the ground/enclosure probe onto the foil) is acceptable? At the mean time doing another test for console unit by using CL1;B;0AP. By performing the test with 0AP, there will be no "mains on applied part" test conducted and we will be safe from frying the probes or even ourselves. I guess this practice is fine and doable. What do you think?

Besides this, is there any limit on the leakage current for US probe, I ever seen 185uA for TEE probe, how about the other US (eg linear, vagina, convex & etc)?


Re: EST Procedures for General Ultrasound [Re: Lau Yew nen] #49829
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As I have probably said many times before, in general (and regardless of which Standard is being followed) I believe there are three pertinent measurements to be carried out during routine electrical safety testing (that is, during normal servicing or maintenance). These are:-

1) Grounding resistance (plug earth pin to unit)
2) Line and Neutral to Earth insulation
3) Risk current

By "risk current" I mean enclosure leakage with the protective earth conductor open circuit. This is the maximum current that could flow through the patient if the ground becomes open and chassis becomes live (ie, if a double-fault condition arises). It should be called "risk current" to distinguish it from "touch current" under SFC. I would test for "risk" (rather than "touch") current, as this represents the worse case, and one that could actually occur under fault conditions.

Note that in well-maintained machines (that is, as long as earth continuity is preserved), the "double-fault condition" mentioned above is very unlikely to occur, as the equipment fuse or breaker will blow if the chassis becomes live in the event of a fault (due, for example, to liquid ingress and [or] component failure). Note also that whatever the maximum allowable "risk current" is, it will still be way below the level of perception (typically 1 mA), and well below harmful levels of current.

Note also that the fuse(s) will blow in the event of a drastic breakdown in basic insulation (test 2). So, if you are behind schedule (and who isn't?), and have time for only one EST:- again, "risk" is the one to go for (in my opinion).

I'm sure that folk on here don't need reminding, but (for completeness) it can be seen, therefore, that the integrity of the grounding conductor is the essential element of electrical safety.

Regarding probes on ultrasound units, I doubt you will find any exposed metal parts there that are also earthed, so (in principle) wrapping metallic foil around the probe, and slapping on a dollop of gel sounds like a pretty creative method, as long as such effort is considered worthwhile. See if you can detect any risk current that way, measured from the probe (or the foil) to true earth (eg, the earth connector on the wall outlet - hopefully).

I would need to refer to manufacturers' specs before commenting on leakage current values for specific probes. But are they talking about "risk current" ... and how do they measure it? Foil and gel?

And (lastly) what sort of readings are you getting in practice? And have you failed any of the probes due to poor electrical safety? smile

Re: EST Procedures for General Ultrasound [Re: Lau Yew nen] #49830
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Meanwhile, here's a link that you may find interesting.

And here's a .pdf about probe failures.

And (again, lastly) if you really want to do the job properly, it looks like you need something like the Fluke ULT-800. Take a look at the manual. No doubt you shall be encouraged to note that it uses a method similar to the one you are already using! Notice, however, that all you seem to get for such expense is a PASS/FAIL indication, which (as you have already mentioned) looks to be 185 uA.

The ULT-2000 from BC Biomedical looks a bit more, er, technical. smile

Re: EST Procedures for General Ultrasound [Re: Geoff Hannis] #49833
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Originally Posted By: Geoff Hannis

Meanwhile, here's a link that you may find interesting.

And here's a .pdf about probe failures.

And (again, lastly) if you really want to do the job properly, it looks like you need something like the Fluke ULT-800. Take a look at the manual. No doubt you shall be encouraged to note that it uses a method similar to the one you are already using! Notice, however, that all you seem to get for such expense is a PASS/FAIL indication, which (as you have already mentioned) looks to be 185 uA.

The ULT-2000 from BC Biomedical looks a bit more, er, technical. smile


Hi Geoff,
Thanks for your reply. ULT-800 and ULT-2000 is an another alternative for this, but it is not economical to purchase this analyzer we have too many US with sooooooo many manufacturers and model (Japan, US, Taiwan, Korea, China & etc), I believe some of the US probe adapter might not available. That is the reason why we are using our current method, which serve the same purpose by measuring the leakage current of the probe, and it applies to all models. smile

Thanks a lot for the reference and nice websites. Appreciated.


Re: EST Procedures for General Ultrasound [Re: Geoff Hannis] #49834
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Hi Geoff,
For automatic EST, it would be in single fault condition. But for Manual, we are doing according to the form given. (I'm so sorry for not able to show the form here as it is a controlled form, company's policies). Based on the form we used for manual EST, we are actually performing DFC.

Originally Posted By: Geoff Hannis

Note also that the fuse(s) will blow in the event of a drastic breakdown in basic insulation (test 2). So, if you are behind schedule (and who isn't?), and have time for only one EST:- again, "risk" is the one to go for (in my opinion).

I'm sure that folk on here don't need reminding, but (for completeness) it can be seen, therefore, that the integrity of the grounding conductor is the essential element of electrical safety.


Totally agreed with you. The integrity of the grounding conductor and connection is the basic element of the Electrical Safety.


Originally Posted By: Geoff Hannis

And (lastly) what sort of readings are you getting in practice? And have you failed any of the probes due to poor electrical safety? smile

So far we only getting value from 0-5uA, nothing more, and we haven't failed in any electrical safety. Usually we will halt EST when we found the probe is damaged, cable exposed, kinked, hole, scratches & etc. We will have to correct the problem by repair it (buy new probe if the repair is not successful), then we will perform EST as the last procedures before completing the work. smile

Re: EST Procedures for General Ultrasound [Re: Lau Yew nen] #73121
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Geoff Hannis Offline
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I recently came across this nice .pdf about testing ultrasound probes. smile

Re: EST Procedures for General Ultrasound [Re: Geoff Hannis] #73122
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Malcolm Offline
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On the same note,something from our German colleagues:

https://www.gossenmetrawatt.com/english/produkte/seculife-ul.htm

Re: EST Procedures for General Ultrasound [Re: Malcolm] #73123
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Looks nice, Malcolm. Have you got one? smile


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