Environmental conditions 60601

[JK_123]

I am confused about what is required in terms of documentation and testing of environmental conditions according to the IEC 60601.
The IEC 60601 states the following for a medical device:

The manufacturer should specify the perfmissible environmental conditions for which a hazard is not induced.
What would be applicable here is the humidity (30%-75%), temperature (+10-40C) and atmospheric pressure (700 - 1060hPa) of the environment.

It also states:
After the ME EQUIPMENT to be tested has been set up for NORMAL USE (according to 5.7), tests are performed within the range of environmental conditions indicated in the technical description.


It is clear to me the IFU has to state the conditions for operating environment, storage environment and transportation environment.
The question is to what extent does this have to be tested? Would a functional test be required on all range boundaries like high humid/low temperature, low humid/low temperature and so on? If so, what kind of test should this be? Just a functional check if everything works under that condition? Or an extensive electrical safety test under all these conditions which seems practically impossible to me.
Or, can a proper written rationale be written up that these conditions have no functional or safety impact to the device?

 

[Peter Selvey]

There is no broad-based test in IEC 60601-1 that proves the device is safe and functions correctly within the specified operating conditions.

In practice, modern components are robust enough that comprehensive environmental testing would be a waste of resources. Rather, there may be some special components that are sensitive to temperature, humidity and/or pressure. This can also depend a lot on the design solutions. For example, manufacturer A might use expensive 0.1% resistors with 10ppm/°C for a critical measurement circuit, which is obviously OK for the 10-40C range. Manufacturer B might use cheaper 1% resistors with 200ppm/°C with software compensation, which in turn needs testing to prove the algorithm works reliably over the temperature range. So it makes sense to review the design, pick out the sensitive parts, and develop special tests that prove those components are OK for the specified range, with some margin as is appropriate for any design. This can be done as part of normal design controls, independent to IEC 60601-1 compliance. The need for a flexible approach is probably the reason why there is no generic test for this aspect.

There are some limited tests in the general standard such as the leakage current and dielectric strength after humidity test of 93%, and also the temperature rise test results are adjusted for the maximum ambient, e.g. if the device is specified for up to 40°C, a test is done in 23°C, and a transformer gets to 90°C, the results will be reported as 107°C. However, these are far from comprehensive. In some particular standards there may be selected performance tests that take into consideration the environmental range, but again these are rarely comprehensive. Probably the most comprehensive is the standard for home use (IEC 60601-1-11) which has various environmental tests with an expectation that basic safety and essential performance is maintained. But even those tests can be ineffective if the manufacturer selects a narrow definition of essential performance, or even no essential performance, which often happens.

Regulations normally have some kind of blanket statement that a device should be safe and effective over the conditions of normal use. But there is usually no strict expectation to provide objective evidence, and in practice it should be flexible depending on the device and technology used.