Product Safety Certificates – Like SIL – What’s Their Purpose?

By J.B. Titus September 14, 2010

In the news recently there’s been some buzz about the product safety certificates around questions like:

    1.)   Are these safety certificates required by insurance companies?

    2.)   Are these safety certificates required by industry standards?

    3.)   Are these safety certificates required by local codes or regulations?

    4.)   And,…….the list goes on?

This blog is a call for comment from anyone who has an opinion.

Some of us might recall that when hardware and software based products were first made available for safety applications they had to be designed, built, and tested to a standard. The first standard that I’m aware of for industry for this purpose was IEC 61508-1 and it required that these products be tested and listed for such use. Everyone today should know that this means that groups/organizations like UL, TUV, and FM (to mention a few) are the testing and “listing” agency’s more formally known in the US as NRTL’s (Nationally Recognized Testing Laboratories). At the completion of their work these laboratories normally issue “stickers” or labels (for the products) and certificates to the manufacturer along with their final bill. A very common application of the “sticker” or label can be recalled by looking at the UL label on the power cord of the toaster in your kitchen. The same or similar situation would occur with your safety relay, safety PLC or other safety device that falls under the hardware and software definition from 61508.

Now let’s shift gears for a moment. Does the UL label on the toaster mean that it’s OK to toss the toaster into a kitchen sink filled with water? Of course not – that would be considered misuse! Now let’s look at the safety certified safety relay with a double set of contacts. If this relay has one set of redundant contacts wired to an actuator and the other set wired to an operator display – has it been applied correctly or is this an example of misuse. Most of you know the answer to this question! It depends!  Yes, it depends on the level of hazard being mitigated. Whether this hazard is SIL 1, 2, 3 – or – Cat B, 1, 2, 3, 4 – or – Pl a, b, c, d, e, the applied mitigation solution can be very simple or very complex.

So, what is the implied necessity for an end user to have the “product” safety certificate on file for a component of a machine? The product safety certificate certainly is unrelated to how the component was actually applied on the machine, correct? Does the certificate actually mean that the product will perform as intended if it is applied correctly? Kinda like your driver’s license, huh? The next question might be – validation?

In my opinion, the core reason to have these safety certificates on file is because it’s a good business practice. Other reasons might include; it’s a union agreement requirement, the President say’s so, it’s part of the corporate safety policy, the city inspector wants to see the certificates, the validation process requires the certificate to release the machine to production, or (I have to throw this one in) the defense lawyer says so!

What other reasons can you add to this list? Share your experiences and opinions on the need for Product Safety Certificates.     

Contact: for “Solutions for Machine Safety.”

Also read:

Residual risk is alive and ever present in machine safety; and

Machine Safety in the US – What Drives Safety Behavior?