Living With Safety Testing

While we take it for granted, the fact that your plant doesn’t burn down due to an electrical fire and your computer doesn’t electrocute you may owe much to safety standards and testing labs. Those logos and stickers on all manner of equipment should remind you that much goes into keeping you, your home, and your plant safe.

By Peter Welander, Control Engineering June 1, 2008
Two real-life certificate lists

While we take it for granted, the fact that your plant doesn’t burn down due to an electrical fire and your computer doesn’t electrocute you may owe much to safety standards and testing labs. Those logos and stickers on all manner of equipment should remind you that much goes into keeping you, your home, and your plant safe.

Imagine if you had to choose a pressure sensor and transmitter for an application where the atmosphere could potentially be explosive. Without safety standards, you would have to evaluate the device on your own to make sure it does not have potential to ignite flammable gasses. Multiply this action over all the devices in a plant, and the benefits of safety testing emerge very quickly.

“Customers rely on product certification agencies to perform testing that they would otherwise need to do themselves,” says Luis Duran, product marketing director, safety and critical control for Invensys Process Systems. “It is a way for customers to reduce the approval process for particular equipment to satisfy those obligations. When I started in this business many years ago, the testing protocols for safety systems were many volumes, and included a number of detailed tests. The main difference between then and now is that back then there were no certification agencies to perform those tests, and customers were doing those tests on their own.”

The people whoc cylinder to move it back and forth. A data logger records the temperature change as the sensor moves from the hot to cool blower, while a counter tabulates the cycles back and forth. This setup can run unattended for as many cycles as the test demands. Control Engineering photo.

Products of all sorts, from consumer to medical to industrial, are tested by nationally recognized testing labs (NRTLs) to make sure that they can perform specific functions safely. Of course, the concept of what constitutes safety depends on the application. For example, a toaster may be safe in a kitchen, but not in an oil refinery.

User companies in an industrial context have to decide what standards are applicable to products in specific applications. In some cases, that choice may be dictated by an outside regulatory agency (including local building and fire inspectors), an industry association, or insurance company. Someone within that group will normally have responsibility for inspecting the plant and making sure the right standards have been applied properly and appropriate products have been selected. In most cases, these inspectors are not from the testing lab.

“That inspection responsibility falls on authorities having jurisdiction,” says John Drengenberg, P.E., manager of global consumer affairs for Underwriters Laboratories (UL). “If you’re building a plant that is manufacturing something considered explosive, the local inspection authority will have to inspect that plant and make sure the components used have the proper certifications for that application. We’re not out in the field. We don’t do any installing or inspecting. We have no way to coerce customers to say they want UL. It’s the local inspection authorities.”

Starting with a standard

An NRTL has to have a standard before it can test anything. The lab may generate its own, or it may test to an external standard. In some cases, a supplier, user, and inspection authority may have to agree on a relevant standard for a situation that is not typical.

If there is no standard, a user trying to choose equipment for a critical installation will have to do internal testing to determine if a product is suitable for the anticipated use. Moreover, the company will be subject to the understanding and whims of any inspectors trying to evaluate those choices and the installation. When there is no objective authority, disagreements can result and projects grind to a halt.

“Two things drive standards development,” says Drengenberg. “First, a change in technology, and second, a preponderance of accident information. If we get statistics that show that something is malfunctioning to the extent that it is causing a safety hazard, we want to know about it. At UL we have a group that does nothing but investigate reports from the field. Our field report group is comprised of investigators that take reports from manufacturers, government agencies, and members of the public, which they then investigate.”

Standards are very specific descriptions written in precise language that leave nothing to interpretation. They cover a number of basic points depending on the situation, including:

  • What an item is supposed to do;

  • Where it can be installed;

  • How it is to work;

  • Construction methods;

  • Internal component selection;

  • Installation instructions;

  • Environmental considerations;

  • Voltage and current ratings; and

  • Potential personal hazards.

An explosion proof device under test at UL. The device is placed in an enclosure that can be flooded with natural gas and air. A spark plug is placed in the area to be tested to ignite the gas if it reaches an unacceptable level. Things do indeed fail tests from time to time and blow up in the process. Control Engineering photo.

These attributes must be outlined clearly enough to inspect or test, so any technician will know exactly what steps to take.

Writing a standard is a careful process that involves a variety of participants. Drengenberg describes the procedure: “Standards are developed on a consensus basis. We have standards technical panels—groups made up of manufacturers; consumer users; large, government agencies; consumer advocates; and even medical doctors, when it’s appropriate. We sit them down and present the scope of the project and our proposed requirement.

“They talk about it, they debate, face-to-face or by email. UL is then obligated to respond to every bit of criticism, such as, ‘We see what you’re proposing, but here are the drawbacks…’ And we evaluate that very carefully. Ultimately to change a standard, we have to get agreement from that standards technical panel. We want to write a standard that’s relevant for now and will be relevant for a good period of time, but we review our standards constantly.”

Testing organizations frequently interact with companies during design phase to prevent them making choices that will make certification more difficult.

Why so many standards?

Modern standards and testing techniques have been developing over the last century or so, and many of the organizations grew to cover specific countries, regions, or industries when companies were much less global. These groups have largely maintained independence, each with its own body of standards. The result is that one can often find multiple standards around the world, or even in the same country, that cover the same ground. Selecting the right ones can therefore be a challenge for end users.

Some products or applications tend to align with one specific lab or another, although this is far from uniform. In the U.S., for example, FM (Factory Mutual) has long been the leader in intrinsically safe devices, whereas UL covers electrical panels and associated equipment. Some devices simply have multiple marks to satisfy everyone.

Suppliers wishing to sell products in different parts of the world soon realize how many agencies there are. International customers and the local authorities that regulate them often have very specific ideas as to what they will accept and what they won’t.

Increasing globalization has not slowed the proliferation of standards, although it may have mitigated the effect by increasing the variety that a local body may accept. This is difficult to quantify and most information is anecdotal, but the conventional wisdom is that local inspectors prefer local standards. An inspector in Russia requiring the local GOST (Gosudarstvenii Standart) is no different than one in Texas preferring UL to TÜV (Technischer Überwachungsverein) from Germany.

Does this mean there has to be a lot of redundant testing to a variety of standards bodies? The answer differs, but there is general agreement that the number of tests required is growing along with associated expenses and time.

“The three major ones we deal with in North America are FM, UL, and CSA (Canadian Standards Association),” says David Hohenstein, department manager of hardware and marketing, for Pepperl+Fuchs’ process automation division. “All three of those can do certifications in the U.S. to U.S. standards, or in Canada to Canadian standards.”

If the standards are similar, is there a way the testing done by one lab can be transferred to another? Hohenstein laughs, “Ahh, there’s the rub. No, there isn’t. They’re all independent, profit-making bodies, and they don’t transfer one to the other, typically. It doesn’t really matter if it’s approved at one and then you submit it to another agency, that doesn’t mean anything to the other agency. They want to do it all themselves.”

Creating global products

A supplier has to determine how many standards are applicable for a given product based on the number of markets and breadth of applications. This information comes primarily from the field.

Scott Hillman, product marketing manager for Honeywell Process Solutions, describes the interaction: “Our ‘voice of the customer’ process tells us which standards we have to get ahead of time, but there are also times where customers say ‘I’ll buy this product for this application if it meets these particular standards.’ Certification is the way to prove that it meets those standards.”

Does everything have to happen at once? Companies approach this differently as they consider promoting products in a variety of markets and regions.

“When we’re first looking at marketability of a product we’ll put together our wish list,” says Hohenstein. “We have our minimum requirements to launch the product and make it industry viable. We have to have ‘x’ approval and ‘y’ approval in order to sell it, and then we have wish list approvals for phase two, phase three, and phase four of the product roll out as we look to grow to a different region or as we expand and consider safety critical applications.

Other companies like to do it all at the start. Sean Keeping, vice president of technology for ABB instrumentation, deals with global launches regularly. He says, “In the last few years, all product releases, regardless of the factory they come from—whether it’s in Europe, Asia, or the U.S.—every product is considered a global product, and that helps define the certifications that we will actually need to launch a product globally.

“When we arrange a product launch, we want to say we have all the necessary product certifications for Europe, the U.S., and Asia. What we don’t want is to be in a position where we launch a product in Europe with European certifications, and then our sales channels in the U.S. says, ‘But we can’t sell that because it doesn’t have U.S. certifications.’ So right at the outset of a project, we define the global certifications. We do not make regional products.”

There are specially constructed bays at UL to test explosion-proof devices, including large items like electric motors. Heavy concrete walls protect workers but the exterior wall is light to blow out during an actual explosion. An operator can control and monitor what is going on in the test bays from a safe distance. Control Engineering photo.

Redundant or conflicting?

Given the variety of standards, do requirements ever conflict? “I wouldn’t call it conflicting requirements,” says Duran, “but we encounter the need to meet redundant requirements and re-test to a particular national standard. That is just part of doing business in particular regions. As an example, any system used in a fire and gas application in China requires certification by the Chinese Fire Authority. The requirements are similar to NFPA72 (National Fire Protection Association), however, we must demonstrate compliance to the Chinese national authorities.”

Testing and beyond

The importance of production and manufacturing issues can complicate testing and change the point in a design cycle where it takes place. “In Europe, we have CE (Conformite Europeenne) certification, and we have to have a CE mark on a product before we actually sell it,” says Keeping. “If you look at the U.S., with UL and FM, it’s extremely difficult to launch a product with UL and FM approval, because you really have to have a serial production product to test. You can’t test a prototype. So UL and FM certification will come six months after we launch a product for that very reason.”

ATEX (Atmosphere Explosibles) explosion-proof certification is another difficult area, says Keeping, “because we have to wait six months to have production product tested. So, for those six months, we have a product that is completed, but without certifications.”

NRTLs know their job is just beginning when a product has been certified. Once a mark has been awarded, an organization normally requires ongoing audits as long as a supplier wants to continue using the mark. This usually involves an agreement that the supplier will submit to inspections and audits, usually without warning, to ensure that nothing has changed in the manufacturing process.

The frequency of these audits depends on the number and nature of products produced under the standard. Small producers may only be visited a few times a year, but very large producers with a large selection of certified products can have inspectors on premises continuously. The costs of these inspections are covered by the supplier through agreements with the lab.

While these procedures may make life complicated for manufacturers, ultimately the results benefit end users. Hillman observes, “At the end of the day, the whole standards and certification business is about two very simple things: quality and compliance. There is a cost to that, so we in the industry try to build those costs into the product as much as we can one time, so customers can share in the benefit.”

Author Information
Peter Welander is process industries editor. Reach him at .

Two real-life certificate lists

Following are two different industrial products and the number of certifications they received to be considered fully marketable for their respective applications.

Pepperl + Fuchs purge and pressurization controller

After development was complete, it took another 10 months and $125,000 to gather the list of certifications below to get the product certified for US, Canada, ATEX, and IEC Ex:

EMC shock and vibration testing;

UL 913;

UL 1203;

CSA C22.2 No. 152-M1984;

NFPA 496;

IEC/EN 60079-0;

IEC/EN 60079-1;

IEC/EN 60079-2;

IEC/EN 60079-11;

EN 61241-0;

EN 61241-1; and

EN 61241-4.

Honeywell Safety Manager SIS platform

NFPA 72 Standard for Fire Protection from FM and TÜV.

TÜV Bayern—Certified to Class 6 (AK6) safety equipment as defined in the following documents:

DIN V VDE 19250;

DIN V VDE 0801 incl. amendment A1;

DIN VDE 0110;

DIN VDE 0116;

DIN VDE 0160 incl. amendment A1;

DIN EN 54-2;

DIN VDE 0883-1; and


IEC 61131-2;

ANSI/ISA S84.01;

CSA Standard C22.2 No. 0-M982 General Requirements–Canadian Electrical Code, Part II;

CSA Standard C22.2 No. 142-M1987 for Process Control Equipment;

UL 508;

UL 991;

UL 1998;

ANSI/ISA S84.01;

FM 3611;

IEC 61131-3 (Functional Logic Diagrams);

IEC 61508:1999, Parts 1-7;

CE directive 89/336/EEC (EMC); and

CE directive 73/23/EEC (Low Voltage).