Startup alarms on all conveyors? How do you do it?

Dear colleagues,

We had a corporate safety audit recently and it was identified that we were lacking starup alarms on all of our conveyors (thats a lot!).

The Ontario, Canada Occupational Health and Safety Act, Industrial Regs. (1998) states...

851-33. Portions of conveyors or other moving machinery that are not visible from the control station, and where starting up may endanger any worker, shall be equiped with automatic start-up warning devices.


I have been a safety activist for years and did not think that this ruling applied to our situation because of our stringent lockout/tagout (at the source) system which would prevent a worker from being endangered by the startup of equipment. What has kept us from having incidents or accidents is the awareness that you don't put yourself into a situation where a machine that can start up automatically, could hurt you. For accidental machine contact we use finger proof guarding on all shafts and pinch points. All conveyors have stop buttons and emergency cord switches along their entire length that are hard wire interlocked to the output relays, independant of automatic control.

We already have audible and visual alarms for dangerous and critical situations and I fear that adding hundreds of additional alarms in close proximity to each other, for routine startups, would create the potential for decreasing overall safety. Most of the veterans around here seem to agree. I was wondering what the general opinion of the forum is.

thanks in advance,
Brian

Today most moving equipment has some form of audible/visible motion alarm. There can be too many places where the machine is in motion and the operator cannot see if it is clear.

It is fairly simple to add. You tie the start button to the "BEGIN MOTION" alarm. When the time out relay completes, it closes the contact that the start button used to close. The machine moves after everybody got warned it was going to move. I have seen some where the operator had to hold the start button until motion begins.

I have seen stacked lights with 3 to 5 lamps of different colors to indicate what the noise maker is indicating.

Brian,

This has nothing to do with lockout/tagout. It is simply to let ANYONE in the proximity of moving equipment know that it is about to start (especially during normal startups . . .). Bottom line - if you aren't the one pushing the start button, you don't know that it is about to start. If there is ANY chance that ANYONE can be in proximity to moving equipment as it starts, this is a very good idea!

We also have signs in some places saying: "Caution - conveyor starts automatically." to keep awareness up. We too have a "practice" of "Be aware - don't put yourself in harm's way."

Marc

Miles of conveyors

At my facility, we have literally miles of conveyors (luckily not in a straight line). There are 7 distinct control panels that operate approx. 1/7 of the conveyor system. We also have rope switches on the entire length and very dilligently practice lockout tagout for all equipment. That said, I currently sound an alarm whenever someone puts the conveyor system in automatic and hits the start PB. A very loud general alarm and flashing light operates at the control panel and usually somewhere at the other remote end. After 5 seconds of alarm, the conveyor start.

I am thinking of changing this just a little to require that the first push of the button sounds the alarm and either the operator holds the button for the 5 seconds or the system will require another push after 5 seconds but before 8 seconds (that way if someone yells something, the system won't just start). Even though I thought this would be a big pain, I am firmly convinced it is the right thing to do. We auto start the system 1 time every couple of weeks (it constantly runs otherwise). We just came out of a 5 day shutdown where there were over 70 people working on the system over those days. It's way too easy for someone to either forget to put a lock on or at the last minute go looking for the wrench they dropped while they were working (but after they took off their lock and saw they were missing a tool). No matter how strict you think everyone follows the rules on lockout tagout, someone will always have a momentary lapse of reason and stick their hand somewhere it shouldn't be (there are several threads here that talk about that). The punishment for that moment of inattention shouldn't be amputation or death - if you can sound an alarm and provide a startup warning.

The last company I worked for supplied and worked on starter equipment for conveyor belts in coal mines. You could literally have someone working on the tail of the conveyor belt and be a mile or more from the belt head and starter box. On all of the systems we supplied, all of the starter boxes were networked, so that when you were preparing to start one belt, and alarm would sound at the head of the next belt, and so on down the line. Most of the time, we had a ten second warning before the belt would actually start.

Joe and others,
thanks for the replies.
I work in a cement plant.
We have probably 500 conveyors, belts, screws, bucket elevators, mills, seperators, dustcollectors, rotory feeders, drag conveyors.
Not one is operated from the field, except with a jog station.
All is controlled centrally and starters are operated from banks of output relays.
We have a Bailey DCS controlling much of it and satellite PLCs controlling the rest.
I tried to estimate the cost and time to install all these new outputs and alarms and my head hurts just thinking of the logistics.
And then where do we stop? What is the cutoff point.
I don't like arbitrary decisions and I probably have a need to challenge authority, but I don't like it.
Now I do like the idea of putting a startup alarm on all of our ball mills.
A poor fellow could be walking along, minding his own business when the 4800 hp motor starts up, blowing a days worth or more of accumulated cement dust in his face and then the 5 pound hammer that the mechanic that had the mill down for repairs, left on the top, comes flying down on his head.
That statisfies the intent of the reg
"and where starting up may endanger any worker"
but a conveyor starting that is guarded at pinch points and you have to reach past the emergency pull cord to even touch? I don't know. Not money and resources well spent and if done wrong....I think the word is cacophony!

Noun: cacophony ... ku'kfunee. A loud harsh or strident noise - blare , blaring , clamor [US], din ... Loud confusing disagreeable sounds. See also: dissonance, noise.

But as always I intend to keep my mind open to the possibility that I could someday be wrong in even some small way.

Tommorrow I have a meeting with the Ministry of Labour to discuss interpretation of the Act(law). I'm fearing he will agree with the company that more is always better. I'll let you know how it goes,

thanks again,
Brian

auto login problems

Sorry, not trying to be unregistered, thought I was loged in,
Brian.

I have 20 years experience in safety and health work.
I can see this is expensive especially after you have rope activated E stops in place.

I have low confidence in
1. Placing a sign. IF a sign is effective just hang a big BE SAFE sign on the gate. Who says they are going to read it? At Boeing there were so many signs somethimes you did not know which one to read.
2. Alarms - Granted this is a little different but people become accustomed to back up alarms on heavy equipment. They also become accustomed to the flashing lites. Result they ignore em.
IF you put an alarm in for a conveyer how do employees know what the alarm means? What do you do put in a recording "Warning starting conveyer XYZ"? I'm not exaclty wild about this either.
I guess the BEST is to have someone with a radio by the conveyer to tell the control room it is OK to start. HE she can always pull the E stop as needed. I'm not sure if this would work all the time either - so I guess you gotta have an OK to start switch (keyed?) at the conveyer. That might really be the safest and shold be fairly "easy ??" to wire into E stop circuit.

The hard thing about safety is to answer the question how much is enough?
and the REALLY hard part is to be right 5 or 10 years later.
Further complicated by "you can make it foolproof, but some fool will prove you wrong.

Dan Bentler

Recently we have started challenging safety audit findings to see if:
1, they are applicable
2, they will actually increase safety

Unfortunately, to many of these things are done with people who have no idea. For example, we were ordered to put automatic CO2 fire extinguishers in every electrical cabinet, when there is nothing burnable inside. They totally missed the old leaky hydraulics that recently caught fire, putting one machine out of action for a month (no one was injured, luckyly). So we are expected to spend our money fixing a non problem while not having enough left to make genuine safety improvements.
(Followup, since that fire they are now demanding that we protect our Scada systems from fire. It was leaking hydralics that caused the problem!!!!! No Scada system was involved or even damaged. I am not making this up.)

In your case, anything that cannot cause an injury (is fully guarded) should not have to be alarmed. If you group start everything, you may also only need a single alarm for your whole area. Autitors are human too, they make mistakes and can be over zelous. As long as you can back up your arguments, you can challenge their orders.

Silver said:

I tried to estimate the cost and time to install all these new outputs and alarms and my head hurts just thinking of the logistics.

Click to expand...

Since you have soooo many to do, you might want to consider using a regular ol' timer wired locally at the conveyors...

A quick drawing:



I would think you could preassemble a bunch of 'retrofit kits' with the timer mounted in the horn's junction box. Add a length of 3 core cable (with ground of course) to wire back to the existing contactor. This would limit the downtime required for installation.

This assumes the contactor coil voltage (and the PLC's output capacity) is appropriate to directly power a horn.

Just giving you other options...


-Eric

Very practical approach, Eric.

Now, to invent a plc with one input and two outputs...

Rats, a regular time does the job just a little to good!

No million dollar idea here.

But a packaged retro kit, hmmmmm..........

If it sells, part of Eric's commision will go to Phil!

Thanks Eric,
All starters are at central MCC rooms, 120vac coil, fed through output relays with min 10amp contact rating, although there are many outputs fed from each 15amp breaker, we would have to be careful of overloading the existing circuits. Most systems start sequentially so this may not be a huge issue. The only real problem then is pulling in the cables from MCC to field to mount the horn(s). This could be up to 2000' each. I think we could find a way to mount the timers in the MCC starters.
It's good to have all the bases covered.
Thanks for the feedback Doug and Dan, good to know we're not alone!

"I guess the BEST is to have someone with a radio by the conveyer to tell the control room it is OK to start. HE she can always pull the E stop as needed."

I don't think they'll hire extra people to do that. We generally run with 3 guys only off day shift.

By the way if a horn sounds in the plant and no one is there to hear it does it make a noise?

thanks,
Brian.

I would do my own risk assessment to see if there were any areas, blind or otherwise, where a person could be on or under a conveyor when it started. I doubt all of the system(s) would need the alarms but it is probable that "sections" could use it.

I have worked with long conveyors that started sequentially, the idea we worked on was "line of sight" using a specific warning light with associated "horn", actually more of a beep beep. I have found that a horn or light alone tends to be ignored but the 2 used together usually obtains an automatic response.

It is possible to "cheat" a little when working with an existing system. One method when the conveyors start sequentially is to connect a timer with the power from the "first" motor to sound an alarm for X period of time. Usually you would need a box for the delay timer so if you have to add a small step down xfrmr it isnt that much of a problem. Depending on the situation it may be possible to use metal clad cable to simplify the installation...ie mount the box with timer/xfrmr, run the metal clad cable to "lead" motor then tie in when not running.

"I would do my own risk assessment to see if there were any areas, blind or otherwise, where a person could be on or under a conveyor when it started. I doubt all of the system(s) would need the alarms but it is probable that "sections" could use it."

Exactly, the inspector agreed that if the company was willing to make almost unlimited resources available the smart thing was to contruct a list of conveyors and other moving equipment and prioritize them by means of risk analysis.
Start at the top and a year and a couple hundred thousand later, we'll have a safer plant and the low risk equipment will likely fall off the back burner. They'll have my full cooperation.

thanks again for the input,

Brian.