The need to maintain and increase safety is ever-present in the chemical process industries (CPI), but what exactly constitutes safety equipment? This roundup of products covers a broad range of equipment, from data buses to non-slip footwear, whose main function is to increase plant safety. Not included here are general-purpose equipment, such as temperature sensors, that can be used in safety-related applications; specialized systems such as safety instrumented systems (SISs); and services such as safety management programs.
Setting the boundaries
A basic principle of safe operations is to stop people and vehicles from going where they shouldn’t. This may require sophisticated security management systems such as Pro-Watch from Honeywell Security (Louisville, Ky.), which deserve an article in their own right. If the main concern is safety rather than security, however, then simpler systems will often suffice.
Rite-Hite Corp. (Milwaukee, Wis.) manufactures physical barrier systems to control access to plant areas such as loading docks. The company’s new EX3 safety gate has a lightweight yet strong barrier made from bright yellow PVC, hinged vertically on steel support posts and with a gas-shock counterbalance for easy opening and closing. The GuardRite SB3 is a modular barrier system based on 6-in.-wide nylon straps, and the Dok-Guardian is a device that stops fork trucks from hitting closed dock doors – a common problem according to Rite-Hite Aftermarket Corp. president and CEO Paul Maly.
Safety remains important after the vehicle has left the loading dock, especially when transporting potentially hazardous goods such as compressed gases. Earlier this year, industrial gas company BOC (Murray Hill, N.J.) – now part of the Linde group – won awards for fleet safety and environmental excellence from the Compressed Gas Association (CGA; Chantilly, Va.; www.cganet.com). The fleet safety award was for deliveries of cylinder gases by the drivers of BOC’s 200 trucks, who during 2005 covered 6.4 million miles in Canada and the U.S.
For applications that do not require a physical barrier, the EZ-SCREEN Type 2 light screen from Banner Engineering Corp. (Minneapolis, Minn.) provides reliable screening for Type 2 applications (IEC 61496-1/-2) – those where the risk is limited to cuts and bruises. The screen can protect areas up to 15 m wide, and complete system prices start at $525. Other versions of the light screen, including explosion-proof models, are available for more challenging applications.
When visual surveillance of people or equipment is the aim, Extreme CCTV (Burnaby, B.C., Canada) has developed what it says is an industry first: explosionproof video cameras that can be used at night thanks to matching infrared LED illuminators. The EX70 series of compact cameras and accessories are certified for Class I, Division 1, T6.
And for applications that demand white light, Dialight Corp. (Farmingdale, N.J.) has introduced LED-based area illumination systems rated Class I, Division 2, T5 for hazardous locations. The weather-resistant lights have rugged cast aluminum housings with stainless steel fittings, and the long life and low power consumption typical of LEDs, says the firm.
Keep fluids in their places…
With the area secure and well-lit, it’s time to turn attention to process hazards. Despite the prevalence of plant automation, many process operations remain manual – and a source of hazards. To reduce the risk that manual valves will be operated in error or by unauthorized personnel, Smith Flow Control (Erlanger, Ky.) has developed the Anti-Tamper Lock (ATL). In normal operation, the ATL allows the valve handwheel or lever to move freely; inserting a key engages the mechanism and allows the valve to be opened or closed, after which the key is withdrawn. The device can be easily adapted to fit most valves, and does not compromise the valve’s pressure rating.
Hoses and hose couplings are another source of fluids-handling hazards. Hose couplings incorporating non-return valves are the most common answer to the risks of coupling separation, but do not generally protect against failure of the hose itself. Smart-Hose Technologies (Philadelphia, Pa.) solves the problem with a stiff coated cable, running inside the length of the hose. In normal operation, the stiffness of the cable holds open a flap valve at each end of the hose. If the hose stretches or ruptures, the compressive force of the cable relaxes and the valves close.
For conventional liquid shutoff applications, Check-All Valve Mfg. Co. (Des Moines, Iowa) has been manufacturing high-quality, spring-loaded, piston-type check valves for over 40 years. Designs include a straightforward single-piece body version; a check valve that can be inserted into a standard union, and other types for flanged joints; and a Type 316 stainless steel cartridge check valve for sanitary applications.
FlowServe Corp. (Irving, Tex.) manufactures check valves in piston, swing and tilting-disc designs under many different brand names. The company’s NAF tilting-disc check valves are popular in the paper and bleach industries, where their unique design gives excellent tightness and minimizes water hammer. The disc geometry allows the valve to open fully at flow velocities down to 0.6 m/s, yet to close fast and quietly when flow ceases. The valves are available in sizes from DN 40 to DN 1000.
For liquid storage tanks, vent valves, flame arrestors and inert gas blanketing systems are often essential. Valve Concepts (Ellsworth, Kan.) offers a large range of such products, including weight-loaded, spring-loaded, and pilot-operated vent valves in sizes up to 12 x 16 in., flame arresters, blanketing valves and manifolds.
…or direct them safely away
Sometimes, of course, process fluids escape from confinement, in which case it is important to be aware of their presence and dispose of them safely. The most dramatic example is a rise in pressure that threatens to burst a vessel or pipe; in this case, a pressure relief valve or bursting disc is often the answer.
Oklahoma Safety Equipment Co. (Oseco; Broken Arrow, Okla.) developed its Pro+ disc for applications requiring an operating pressure up to 95% of the burst pressure. Scoring on the vent side allows the disc to present a smooth surface on the process side and prevents fragmentation, making the device ideal for protecting downstream relief valves.
Continental Disc Corp. (Liberty, Miss.), which has been in business for 40 years, was the first U.S. rupture disc manufacturer to be approved for CE marking of its products under the European Union’s Pressure Equipment Directive. The company’s latest product is the SANITRX LP, designed for the pharmaceutical and biotech industries. Based on the established SANITRX rupture disc, it is available with even lower burst pressures and with a much lower flow-resistance factor.
Rupture Pin Technology (Oklahoma City, Okla.) uses a slender column – the rupture pin or buckling pin – as the pressure-responsive element to create relief devices that are economical and reliable. The pin, which is in longitudinal compression, supports a valve seat that contains the process fluid; being outside the fluid path, the pin is not at risk of corrosion. The valve opens when the pin fails through buckling. The relief pressure can be controlled with great precision, says the company, and the device does not suffer premature fatigue failures.
If a conventional pressure relief valve is preferred, Gas technology specialist Witt-Gasetechnik GmbH (Witten, Germany) offers TÜV-certified versions for pressures up to 100 bar. The new models in the SV809/810 range are made from brass or stainless steel and are suitable for small-scale applications such as cylinder gases. A manual venting version allows the valve
to be tested easily after installation.
When it’s too late to stop a liquid spill, some form of containment kit is required. An example is the Chem-Trap from Andax Environmental Corp. (St. Marys, Kan.), a portable system that is said to provide 100% containment in less than 5 s. Made from orange polyethylene and with a volume of 65 gal., this device is ideal for handling leaking drums. An optional drain system, hoses and liquid bags simplify cleanup.
Toxic and flammable vapors
For areas where flammable gases may be present, effective electrical grounding is essential. Newson Gale Inc. (Lakewood, N.J.) manufactures a range of grounding equipment, including the Earth-Rite PLUS interlock system. This consists of an earthing junction box, a clamp with a 32-ft. coiled cable, and a control box that, when appropriately wired, confirms the existence of a proper grounding path before allowing powder or liquid transfer to begin.
If toxic vapors are the issue, personal gas monitors are likely to form part of the plant’s safety strategy. One such device is the GasBadge Plus from Industrial Scientific Corp. (Oakdale, Pa.), a two-year maintenance-free monitor that is rated to IP66/67 for protection against dust and water ingress, and is also intrinsically safe. The 2.5-ounce device is rugged, has a versatile display and alarm system, and is available for a variety of gases.
Said to be maintenance-free for two years or even longer is the Altair single-gas detector from MSA Europe (Berlin, Germany). It has three sensor options – carbon monoxide, hydrogen sulfide and oxygen – and is said to be one of the most economical gas monitors on the market. Single-button operation and a rubberized housing make the monitor easy to use, while visual, audible and vibrating alarms ensure safety. An infrared PC link can be used to download alarm data and change setpoints.
Draeger Safety, Inc. (Pittsburgh, Pa.) recently launched the X-am 7000 PID five-gas detector, featuring two sensor slots that can accommodate any combination of photoionization (PID), infrared or catalytic sensor. The other three sensor slots are for gas-specific electrochemical sensors. Typical applications are in confined-space work and for area monitoring in wastewater treatment, chemical and petrochemical plants. Draeger Safety also manufactures breathing apparatus, including the PARAT-C smoke escape hood, and fire training simulators.
Personal protection
While personal protective equipment (PPE) should always be considered the last line of defense in safety, that certainly does not mean that it is unimportant. The Western European market for “above the neck” PPE is close to saturation, reports market consultancy Frost & Sullivan (London, U.K.; (http://chemicals.frost.com), but new legislation and the emergence of niche applications are keeping sales buoyant despite pressure from low-cost goods manufactured in the far east.
An example of new legislation is the European Union’s Noise at Work Directive (2003/10/EC), which requires more workers to wear hearing protection, and new rules for fire safety helmets. New niche markets include laser eye safety and electronic earmuffs, which help workers communicate in noisy environments.
Where noise is a workplace issue, both lab-quality and personal monitoring equipment may be required. Larson Davis (Provo, Utah) manufactures the Soundtrack LxT sound level meter, to which it has recently added a comprehensive time history data logging option. With operator route prompts and digital voice annotation, it provides an easy way to manage route or task-based workplace noise surveys. The company’s Spark personal noise dosimeters have recently received additional ATEX approvals (II 2 G, EEx ib IIB T4) for use in hazardous areas.