Richard, It really depends on the type of protection that is being employed in a particular product. If you want more details, contact me directly. There are several methods that are typically used, two of the most common being:
Intrinsically Safe (Division 1) /Non-Incendive (Division 2) Explosion Proof I assume that you are inquiring about Intrinsically safe/Non-Incendive as this is probably the most test intensive To summarize 100 pages of a standard into 1 paragraph: Intrinsically Safe/Non-Incendive: This method relies on the circuitry internal to the product as well as the wiring to and from the product (if it is a permanent installation). This method of protection requires a large amount of circuit analysis to determine the "theoretical" energy available at points of potential spark release (switches, relays, motors etc). Once the theoretical value of energy has been determined, you can compare this with published ignition curves to determine what spark ignition testing you need to conduct. Spark ignition testing is where the make/break portion of the circuit is placed in an explosive atmosphere and cycled a minimum of 1600 times. (Note: The actual circuit is placed outside the explosive atmosphere, and the circuit is switched using a specialized test setup with a cadmium disk and tungsten electrodes.) If ignition occurs in this atmosphere, the circuit is deemed to have too much energy use in that particular atmosphere and you will either need to drop the investigation back to a lower gas group and retest, or redesign the circuit to limit the amount of available energy. With this method, you want to minimize the amount of capacitance and inductance that you have in your circuit, and to increase the amount of resistance as much as possible. Also conducted are drop tests from 1m on to concrete (for portable apparatus) and temperature tests to determine the maximum temperature in the product. If you are looking for more detail than that, please contact me off line and I will be happy to discuss further. Kevin Robinson Senior Project Engineer/QA Safety Laboratory MET Laboratories-Baltimore Phone: 410-354-3300 x 361 Fax: 410-354-3313 > -----Original Message----- > From: richwo...@tycoint.com [SMTP:richwo...@tycoint.com] > Sent: Monday, February 04, 2002 11:00 AM > To: emc-p...@majordomo.ieee.org > Subject: Haz Loc Testing > > > It would be appreciated if someone would provide me with a brief overview > of > the testing that is performed in order to classify electronic equipment > for > use in a hazardous location where fuel vapors are located. > > Richard Woods > Sensormatic Electronics > Tyco International > > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson: pstc_ad...@garretson.org > Dave Heald davehe...@mediaone.net > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > No longer online until our new server is brought online and the old > messages are imported into the new server. ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
