If you read the documents I recommended in my previous post carefully, they will answer all your questions.
In my opinion this machine is within the scope of the Machinery Directive. It is clearly "an assembly of linked parts or components, at least one of which moves," and the risks are not "mainly of electrical origin" and therefore the exclusion from the Machinery Directive for equipment within the scope of the LVD cannot be applied. Since the machine is not "hand-held portable machines and hand-guided" and one can certainly envisage situations where the risks would be reduced by the availability of an emergency stop, the machinery directive requires an e-stop to be fitted. EN 61010 is not harmonised under the Machinery Directive. You therefore cannot rely on this standard on which to base a claim of compliance with the Directive in respect of the electrical (or any other) risks. There are probably 20 or so other standards which you will need to know at least something about in order to make this machine meet the Directive. You can only meet the applicable standards if you use hardwired logic to operate the emergency stop. You could possibly justify not complying with the standard if you used a programmable system which meets an adequate category of EN 954-1 but you will almost certainly find designing this is more expensive than using off-the-shelf safety relays to provide the E-stop function independently from the process control computer. The emergency stop must prevent any dangerous condition developing further once it is pressed. There is no defined period during which the stop must take place - it must happen 'as quickly as possible'. If possible, the emergency stop must remove the dangerous condition, but it must do so without creating any new risks. The operator must not have to consider the consequences of pressing the e-stop button before it is pressed. All of this is in the Directive. The e-stop button must actuate the e-stop function immediately, which is not to say that the e-stop cannot consist of a sequence of events rather than an immediate removal of power. In your case, I can see no reason not to have an immediate cessation of all motion and a release of pressure, but you still have not given enough information for me to be definitive about this - if for instance, the material is toxic, then you probably don't want to release the pressure in an uncontrolled fashion. The button must remain latched in position. Dis-engaging the e-stop button must not re-start the machine - there must be a separate re-start function. My recommendation to you is that you spend some time doing your homework with the relevant standards, or if you don't have time for this, get your wallet out and pay for some expert advice from someone else who already knows what the standards say. Nick. At 2:24 pm -0800 26/1/06, Joel Sandberg wrote: > To List Members; > Thank you, to those who have already tried to provide information. >Several have said you need to know more about the machine before you >can give advise, so here goes: > >The instrument is powered by AC mains (115 in the US, 220 in Europe). >The max voltage in the machine is AC mains. >The machine is subject to the LVD. >The primary standard used is EN-61010 (Measurment and laboratory equipment). > >The only moving parts/motion vissible to the operator (i.e. outside >of the cabinet) is the load door for the sample. For on one version >of the machine the door is moved manually, for the "deluxe" version >the door is moved by long stoke (6") air cyclinders. > >Internally the system can build 50,000 psi of hydralic pressure. >A motor drives a ram to build pressure. >There is a safety rupture disc (with material certs on every lot). > >An internal compute! r runs the process. > >So now . . . . > >Is an emegency stop switch manditory? > >Must an emegency stop switch be a hardware only function, or can it >operate through the machine's computer and software? > >Does the emergency stop switch have to turn off power to the >machine, or can it just stop the offending action, while leaving >power on? > >What sort of responce time should be expected for an emergency stop switch : >- How long (realy how short a time) must the operator hold >emergency stop switch in order for it to operate (i.e when I want to >hit the button and run, how long to I need to stand there and hold >the button before it functions)? > > >Is this machine subject tot the Machinery Directive? >It is subject to the LVD, but are the risks primarily of an electrical origin? >Who makes that judgement? (I guess the machine design company.) > >Thank you. > >J. Sandberg >! > > > >Do you Yahoo!? >With a free 1 GB, there's more in store with ><http://us.rd.yahoo.com/mail_us/taglin s/mailstorage/*http://mail.yahoo.com/>Yahoo! >Mail. - >---------------------------------------------------------------- >This message is from the IEEE Product Safety Engineering Society >emc-pstc discussion list. Website: http://www.ieee-pses.org/ > >To post a message to the list, send your e-mail to [email protected] > >Instructions: http://listserv.ieee.org/request/user-guide.html > >List rules: http://www.ieee-pses.org/listrules.html > >For help, send mail to the list administrators: > >Scott Douglas [email protected] Mike Cantwell [email protected] > >For policy questions, send mail to: > >Jim Bacher: [email protected] David Heald: [email protected] > >All emc-pstc postings are archived and searchable on the web at: > >http://www.ieeecommunities.org/emc-pstc - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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