Page 225 - Boiler_Operators_Handbook,_Second_Edition

210 Boiler Operator’s Handbook

pressed past the location of the bleed connection. They CONTROLS AND INSTRUMENTATION
couldn’t stop excessive leaking because the entire pack-
ing set was exposed to the high pressure water and the Controls are the robots that do the boiler opera-
erosion along the shaft was getting worse. tor’s bidding. Without them we would be very tired at
The split in the lantern ring should always be set the end of a shift because we would have to make every
90 degrees from the split in any pump casing to provide little adjustment that the controls make for us. Instru-
a clear indication that it’s a lantern ring and not the bot- ments are an extension of our eyes and ears to allow
tom of the packing gland. If there’s a piping connection us to know what’s going on in the process and it’s im-
at the packing gland I like to open it up so I can look portant the information they give us is correct. It makes
into the gland while I’m re-packing it to make certain sense to maintain them so they keep doing their job.
the lantern ring matches up to the opening. Sometimes There’s a separate section on the function and operation
you can get the count wrong when removing the pack- of controls and instruments in this book; this part is de-
ing because it comes out in pieces so it doesn’t hurt to voted only to their maintenance.
spend the extra time to make certain the lantern ring is I’ll go on several times in this book about how
positioned properly. Yes, I have had to take it back out great the modern microprocessor based controls are;
to add or remove a piece of packing so the lantern ring that’s because they are. They make our jobs as operators
is positioned properly.` so much easier than it was when I was operating boiler
Packing of air actuators, compressors, etc., where plants. They’re almost maintenance free! You do have to
there’s no fluid for lubrication will have grease fittings make certain cooling is maintained by keeping dust and
or piped oil connections to apply grease or oil to lubri- dirt out of the slots and vents of devices and panels and
cate them. These usually incorporate a lantern ring to make sure they don’t get wet but that’s about it.
distribute the lubrication. Those packing glands use the Speaking of getting wet, I’ve seen more control
lubricant as part of the seal. It’s important to follow the hardware lost to water leaking into panels than for any
manufacturer’s instructions with that packing because other cause. It never ceases to amaze me how we en-
some have to be soaked in the oil or grease before in- gineers manage to do such dumb things as lay out an
stallation in the packing gland while others have to be entire control panel right under a shower room. It’s also
installed dry then “charged” with the lubricant before stupid to remove something from a panel and leave the
putting the equipment in service. opening for water to enter. I would sure like a nickel for
Valves and a few other pieces of equipment have every time I found a transmitter or control valve with
very limited movement of the shaft through the pack- the cover off because someone forgot or was too damn
ing so there is little need for extensive lubrication. In lazy to put it back. Even small conduit covers can admit
most cases the lubricant is part of the packing, typically water that can find its way into a control panel or device.
graphite. There is no need for leakage of the fluid to The wise operator looks for such things on every round
lubricate the shaft. So, pumps and other devices with and does something to restore enclosure integrity when
moving shafts should leak to a degree but valves and de- he spots a problem. He also carries a clean rag to dust off
vices like a Keckley float controller shouldn’t leak. The cooling vents.
most important maintenance practice for those packing Those of us that are still stuck with maintaining
glands is to tighten the packing as soon as you see it pneumatic controls know the most important thing to
leaking. keep up is the air compressor, storage tank, filters and
Every time you operate a valve check the packing dryer. Makes sense doesn’t it? If the compressor fails
gland afterward and tighten it immediately if you see a then the controls won’t work. If the tank floods because
leak. Quick response to a leak can prevent the need to we forget to drain condensate the controls get to try to
completely re-pack the valve. If that leak is allowed to work on water instead of air. If the filters get overloaded
continue it will cut through the packing, destroying it then the compressor won’t work or the controls get to
and making it impossible to seal by simply tightening try to work on oil. The oil coalescing filter and dryer are
the gland. there to ensure we have the clean dry air the controls
Since operators are the ones that open and close manufacturer specified.
valves. And, since that’s the only time the seal be- Without clean dry air all we can expect is control
tween packing and shaft is broken; there’s no question problem after control problem. Refer to the previous
that tightening valve packing is an operator’s respon- section on lubrication and make sure you always check
sibility. the oil level in the compressor. Keep the fins on any air