If much work is to be done inside the analyzer shelter after it is in place, the construction schedule must recognize that a 10 ft x 12 ft analyzer house, for example, cannot accommodate two electricians, two pipefitters and two analyzer technicians inside at the same time. In this example, two workers at one time is probably the most that can work safely and efficiently inside the analyzer house.
Analyzer shelter and analyzer system constructability concerns should be raised early in the project scope development, again during construction estimating and again during the construction kickoff meeting.
Safety and Ergonomics
The most effective safety and ergonomic approach is to eliminate the hazard so that it never needs to be addressed. In other words, if a hot SHS heater does not exist, it will not burn anyone; if there is no heavy gas cylinder to move, it will not result in back injuries; if an arcing relay does not exist, it will not initiate a fire or explosion.
But this is not always possible—samples often have to be heated, gas cylinders must be used in most applications and most analyzer systems have electrical components. Therefore, we include engineering controls like cage guards around hot surfaces, truck lifts and hand trucks for cylinder handling and purged or sealed enclosures for electrical devices.
The least effective, but sometimes the only approach is administrative controls. Administrative controls often accompany engineering controls for the times that the latter must be removed or bypassed to effect maintenance and service or operations-required modifications.
Effectively writing and implementing administrative controls requires complete, well-written engineering documentation and trained, well-motivated personnel. Training begins with general safety and technical training. Next, the personnel must be trained to understand and operate the equipment for which they are or will be responsible.
Management of change (MoC) and task safety instructions (TSI) are the most important tools in this process. The MoC is required in the United States by OSHA 29 CFR 1910.119. We do not have space here to address MoCs in detail, but it will suffice to state that the MoC for an analyzer system must make operations and maintenance personnel aware of changes to operating procedures, equipment, the operating process; safety requirements; regulations; safety hardware and firmware; failures and failure rates; testing; and documentation.
Task safety instructions (TSI) are a procedural checklist and guide as to how a technician actually performs a specific field task. For example, the TSI for changing an SHS sample filter might include stepwise instructions to obtain a unit work permit, lockout and tagout the analyzer system, the valve sequence to use plant nitrogen to block and bleed the sample from the filter, the correct filter part number and size, and how to reverse the procedure.
Lock the door!
Most users lock analyzer houses, with only the analyzer technician, analyzer reliability supervisor and a shift or operations superintendent having a key. This practice benefits safety, ergonomics, and reliability by preventing unauthorized personnel from entering the analyzer shelter to (1) take “work breaks” that compromise personnel safety and equipment reliability, (2) store unrelated and unauthorized items in the analyzer shelter, (3) prevent unknown, though often well-meaning, workers from tampering with analyzer systems in such a way that compromises personnel safety, equipment reliability and operations, (4) ensure that all work inside the analyzer shelter is authorized by operations through the work permit, lockout/tagout and personnel safety headcount procedures, and (5) ensure that work is documented in maintenance work logs. Analyzer systems installed only in field cabinets should be locked for similar reasons, with similar access control in place.
Users should always comply with the latest appropriate national, state and local codes, industry standards and practices, and corporate and site standards and practices before designing, engineering, constructing and operating these types of equipment.
In this and the previous article, we have reviewed some major safety and ergonomic challenges often encountered in the design, engineering and operation of analyzer systems. Readers undoubtedly have many specific examples and concerns to add to those in this discussion. Therefore, readers are encouraged to develop their own lists, based upon the codes, regulations, company, specific site and operating unit needs, and personal experience and work across disciplines and along process analyzer system life-cycle stages to ensure that analyzer systems and shelters are as safe and ergonomic as available technology allows.
- Gruhn, Paul, PE. and Harry L. Cheddie, P.E., Safety Shutdown Systems: Design, Analysis and Justification, ISA, Research Triangle Park, NC, USA, 1998.
- Nichols, Gary D. PE. “Process Analyzer System Safety and Ergonomics I”, Control, web exclusive, August 2007.
- Nichols, Gary D., PE. “Cost Estimating for Process Analyzer Projects and Reliability II”, Control magazine, April, 2007, pg. 63.
- Nichols, Gary D., PE. “Cost Estimating for Process Analyzer Projects and Reliability I”, Control, March 2007, pg. 59.
- Nichols, Gary D., .E, “Accurately Scoping Process Analyzer Projects”, Control October 2006, pg. 69.
- U.S. Department of Labor, Occupational Safety and Health Administration, Code of Federal Regulations, 29 CFR 1910.
Go to www.controlglobal.com/10nichols.html for additional references and information about process analyzer projects and safety.
Gary D. Nichols, PE, is a principal control systems engineer at Jacobs Engineering Group. He can be reached at firstname.lastname@example.org.