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Safety First

Avoiding potential hazards in a neon-shop environment

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Rising healthcare costs impact people worldwide. According to statistics, work-related accidents and their effects are major cost contributors. Although neon shops aren’t more or less safe than other related work environments, neon professionals can make their workplaces intrinsically safer by acknowledging specific hazards.

Daily routine, work safety’s worst enemy, can make you indifferent to possible hazards. Warning slogans have become nearly useless due to numerous legal cases involving product manufacturers who’ve been forced to incorporate such senseless warnings as "Don’t use hairdryers while sleeping," and "Microwaves aren’t intended to dry live animals."

This month, I’ll address some safety points for a neon shop.

Contrary to popular belief, aging tables, not bombarder transformers, cause most electrical accidents in neon shops. Here’s why: Neon tubes are usually energized while unattended in an open, unsafe setup. Also, tube aging often isn’t considered an important part of tube manufacturing and quality control.

Typically, a shock from an aging transformer won’t kill you, but such secondary effects as burns and nervous contractions aren’t pleasant either. Most shops I’ve visited have had either no fixed setup for aging (just a kitchen table and a 15/60 transformer with a linecord and plug), or a fixed setup in which the red, warning-light bulb was burnt out and hadn’t been replaced. In any case, the open, high-voltage wiring resembled a stack of spaghetti rather than a proper electrical setup.

I saw the most practical and intrinsically safe aging system in a neon shop in the Netherlands (see ST, September 2003, page 35). There, one shop corner is separated by a grounded wall made of chicken wire (Fig. 1) stapled to a wooden frame comprising 2 x 4-in. beams that extended from floor to ceiling. All wire segments are electrically bonded together and well grounded.

This compartment can be accessed through a door with an automated switch. All aging transformers inside (colored GTO leads help identify the circuits) are connected via illuminated on/off switches to a main relay that serves as a general main interruptor for the transformers (in addition to the manual branch disconnect).

The relay control solenoid is wired accordingly (Fig. 2), so the relay will energize when a push button, mounted on the outside of the door, is pressed, and de-energize when the door is opened by the door switch. Note that there’s no push button "on" switch accessible from the inside of the cabinet. The door must be closed before the "start" push button becomes functional. In addition, on the outside and inside, there are approximately three "emergency-stop" push buttons.

The tubes hang from the wire fence via small hooks (from a butcher shop) and are interconnected with small, alligator-clip jumpers. Closed rooms aren’t recommended for aging — not because you can’t see inside, but rather, because co-workers won’t be able see or hear if you encounter trouble while inside the room.

The bombarding table

During tube vacuum processing, most accidents occur when workers don’t concentrate or carelessly attempt to do something out of the ordinary. For this reason, only one person should be allowed to operate the pumping system/bombarder, and all other employees should remain at a distance and cause no distractions. This way, the pumper is aware of the tubes’ and system’s condition at all times. Technical devices, such as key switches, are typically used to lock out the bombarder. It’s also wise to mount a "light fence" (a multiple-beam light barrier) to the table, so, when an object (like a hand) comes close to the table, it switches off the high voltage.

Flashbacks (see ST, February 2003, page 16) are also dangerous. Unless you have a completely metal, properly grounded manifold, or pneumatically actuated stopcocks, never touch a stopcock while the bombarder is on. To facilitate this practice, simply place the bombarder’s push button "on" switch in such position that your free hand can’t reach any stopcock at the same time. Or, simply connect two push buttons in series and mount them approximately 3 ft. apart so you need both hands to activate the bombarder (this setup is similar to that found on metalwork brakes).

Some local, work-safety organizations require placing the entire bombarding table in a separate room/compartment with door interlocks to block access and sight between the operating and tube positions. Of course, this never works out well, so I suggest incorporating the light barrier.

Mercury

Health fanatics often write and discuss potential mercury dangers. Regarding mercury use in neon and fluorescent lamps, consider two facts. First, mercury vapor gas discharge is, and will be for decades, the most efficient means to convert electricity into light. Second, mercury is only hazardous when its vapors or compounds enter the human body in an uncontrolled manner. If you handle the substance carefully, it will be harmless to you and your environment.

It’s important to clean up all spills immediately and thoroughly. I don’t prefer using a syringe because the amount of mercury dispensed into the tubulation is hard to control, and sometimes, it’s hard to stop small droplets from spilling out if the syringe is lying on a table. Instead of costly special dispensers, I prefer using a simple, tiny pipette (also called a "Pasteur" pipette) that comprises 6-in. tubulation glass, pulled to a long, thin tip and operated via a tiny rubber pipette ball from a lab supply house.

Only take the amount really needed for a specific tube from the glass storage bottle and immediately insert it into the trap before the tube is connected to the manifold. By completely emptying the pipette, no mercury can evaporate. Old and dirty mercury should be stored under water (to prevent evaporation) in a plastic-coated glass bottle and periodically given to a proper recycling organization. To further enhance safety, refuse any mercury-repair jobs, dispose of used and unbroken mercury tubes properly, invest in a spill-cleanup set and have employees tested routinely for heavy metals.

The bending area

Cuts and burns are primary hazards in a neon shop’s bending area. Safety requires cleaning the work area regularly by sweeping the bending table and surrounding floor, and storing or disposing of any materials not needed for an upcoming job.

Implement bending-area safety when setting up a neon shop. For example, at the "Exit" door, incorporate a manual, main-gas valve and an electrical, solenoid, gas valve connected to the air blower to prevent gas from entering the air line. Check valves (which should be one-way) will operate properly only in high-pressure lines, like oxygen lines, but not in a low- pressure gas line. Also, flashback arrestors at the mixer valves can prevent possible hazards. Only a licensed professional should install gas-manifold setups.

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