Afternoon oh learned ones.

I've been in discussion with a colleague about the pre-use checking of light guards / curtains. This will be a simple operator check to break the beam to see if the equipment stops as it should an nothing more.

Now, rather than use a physical operatives hand (although the guarding is a sufficient distance that the hand would not com in to contact with the machinery) I have been asked to source the official British Standard Safety Finger. Now I have to be honest I'd never heard of one but looked it up and they are pricey.

I have suggested that we use a wooden ruler, a 30cm one which would provide added distance from the guard further removing the operative from the hazard. I tested this and it worked fine and broke the beam.

This has been debunked and I've been told that the testing finger must be 12mm thick and 80mm long and its what we must use to test the guards.

Does anyone know where it states these safety fingers must be used? I have to admit that in previous businesses the operator would test by using his / her fingertip to break the beam. 

Am I being a bit thick an simplistic with the ruler???

Originally Posted by: Holliday42333

Years ago a PUWER specialist engineer taught me the machinery safety 'Rule of Spoon' (thather than thumb).

Use a 6 inch wooded spoon held by the bowl to test machinery guarding.  No, its not a British Standard device but it works just as well.  I've been using it ever since when required and is far easier to explain than the Safety of Machinery British Standards

Thanks, I like the wooden spoon idea. Certainly meets the length and thickness criteria!

I once used a British Standard courgette (or at least that is what I introduced it as) to test for crushing risk.

To be serious for a moment, where it might state that you have to use the British Standard Finger would be in a documented quality procedure which you might have if you were, for example, a manufacturer of light guards checking that your products operate to requirements, or a test house certifying new designs of light guards, or perhaps if you were conducting a factory acceptance test to prove whether a new one operated to requirements.

It would be quite bizarre to have such a procedure for an operator's pre-use check which is only asking if the thing is working or not.

firesafety. I can see that your biro would work if the guard was immediately adjacent to the danger point.

As example a fixed double angle in front of the inrunning nip between two rollers on e.g. a printing press.

The tables showing the relationship between distance from danger and maximum permissible opening were updated in 1975, when investigations found that previous guidance worked for white men but not for the increasing proportion of the industrial workforce who were of other sex and/or ethnicity.

So, as example, apparently women of Asian origin working in the textiles factories in places such as Leicester had long thin fingers which were getting through the gaps in the fixed guards and getting caught in dangerous machinery.

However, the relevant table in BS5304 assumed that a gap of no more than 6mm was good enough - would protect presumably at least 95% [standard statistical basis] of the workforce. 

Now I have measured my biro - 6mm across. So entirely OK as a "test finger" where the guard is immediately alongside the danger point.

But, if the guard is set a distance back from the danger point then specifying a maximum of 6mm would be entirely OTT.

I can imagine the engineeers in the factory you were advising struggling when you demanded the replacement of guards which might be entirely compliant with the requirements of the relevant BS EN standard - and if relatively new, the manufacturers of the machines also.

How would you propose to get the gap betwen the top guard of a huge circular saw and the top of a UK grown tree trunk it is cutting down to 6mm? It's NOT "practicable", let alone "reasonably practicable" and this was recognised in legislation in 1922. The shape of tree trunks hasn't changed in the last 101 years.

....and even if you can keep that gap down to the 12mm set in the 1922 and then 1974 Woodworking Machines Regulations if the operation is hand fed then there is still a sizeable amount of unguarded saw blade above the table once the material has gone through.

Now let's move on beyond the tree trunk and assume that we are cutting "squared stock". It could be say 50mm thick. You can feed it through a tunnel guard, but that guard is going to have an opening of much more than 6mm so your biro test isn't going to work.

You could, of course ban the use of any machine where the opening is more than 6mm.

If so, how will we produce scaffold boards, or MDF doors for your kitchen?

May be we should simply export all manufacturing and leave others to clean up the blood?

I have worked on large power presses making, amongst things, "motor vehicle parts". They had "sweep away" guards to stop my head or any other part of my body being crushed between the tools of a 400 ton press. The guard did what it said - it swept me out of the way BEFORE the top tool(s) came down.

firesafety

Suppose these people were working on power presses or MOST other production machinery, the guarding is usually some distance from the danger point.

...and if that was the case your biro test would often have been entirely inappropriate.....and the further from the danger point, the more so.

So your blanket statement:

I use a biro to check the spaces.  If the pen went trough the guard was replaced.

...sends a message of not understanding the principles set out in the relevant BS EN on how to judge what opening IS acceptable.

Whether or not I think that you have "some common sense when checking the distance and gaps"

....is somewhat immaterial if someone on their machinery safety learning curve comes nn these Forums and goes away with a biro thickness rule as their guide to "good practice" in terms of openings in machine guards or any of the other circumstances where there are long standing conventions on DOs and DON'Ts in terms of gaps between guards/other other safety devices and whatever is being processed.

This discussion seems to have grown arms and legs. This is simply to test, does the light guard operate correctly? If the beam is broken does the machine stop. Nothing about the distance it is from the machine (its set back so you'd actually have to put your arm through to touch the machinery).

Just a simple pass / fail test for the operator to do.

I'm just trying to balance the argument that a 50p spoon / ruler (better not mention carrots or courgettes that won't go down well) will do the job of a £460 metal and plastic finger.

So I take it no one can tell me the reg, ACOP or guidance that says it must be the BS finger? 

Well I have a meeting later which I am sure it will get mentioned so if I am pointed in that direction I shall update you.

Originally Posted by: M.cooper.99

Afternoon,

I might be too late and/or you may already know this. I think HSG180: Application of electro-sensitive protective equipment using light curtains and light beam devices to machinery is what you are looking for.

Application of electro-sensitive protective equipment using light curtains and light beam devices to machinery - HSG180 (hse.gov.uk)

HSG180 only states that a test piece with an appropriate diameter should be used and that a test piece is defined as "An opaque cylindrical element used to verify the detection capability of the active opto-electronic protective device (AOPD)"

An opaque cylindrical element = Wooden spoon handle / carrot.

Mind you I would say that!