Re: Haz Loc Testing
Hi Richard, It has been a while since I worked with UL 698, but I was involved in some of the testing that was performed to get Square D Co.'s Haz Loc units Listed. I witnessed some relatively primitive testing in the basement of UL's Ohio St. building (before Northbrook UL was in downtown Chicago), where engineers and techs crouched behind file cabinets and columns when they touched off a test. I built and operated a slightly more refined version of that system at Square D had UL witness data for certification. UL Northbrook later built a very sophisticated test lab. The test unit was often a cast iron or aluminum box with wide, flat machined flanges bolted together to house an electromagnetically actuated switch , sometimes with a shaft for a mechanically actuated switch. The idea is that the ambient flammable mixture will get into the unit there will be a switch arc that will ignite that mix. The enclosure is supposed to contain the flame front either by brute strength, or by cooling the expanding flame front below combustion temperature in the flange or shaft sleeve passage from inside to ambient. Conduit wire runs were sealed near the box with glands poured with plaster of paris. The EUT was placed into a larger box with a Saran Wrap lid. For the category we wanted, the test method called for a stoichiometric mixture (optimized for maximum combustion) of hydrogen air to be fed into top of the eut enclosure (lighter than air mix fills from the top down) via a small pipe that passed through a shutoff valve, through the outer box, tapped in to the EUT casting. A similar pipe exhausted at the bottom of the EUT and outside the outer box through a shutoff valve. That mix was piped through another shutoff valve into the top of the outer box and exhausted from the bottom of that box via a shutoff valve. After sampling inlet and outlet mixtures until they read the same, all valves were shut pipes disconnected, isolating the EUT inside an envelope of flammable mix. The mix in the EUT was then ignited by its own contacts and/or by a spark plug. If the Saran Wrap lid remained intact it was a pass. If not, everybody within 1/4 mile knew about it. The pressure pulse inside the EUT was measured by a piezoelectric transducer. A series of tests was run to find the maximum pressure. That maximum pressure was used as basis for a hydrostatic pressure test, which I vaguely recall might have been at 4X the pulse reading.No cracks permitted. Other tests are involved for other categories, such as temperature under a dust blanket, for units intended for grain mills, etc., but above is the exciting part. Caveat - Don't try it at home! Hydrogen molecule is very small so it leaks lots the flame front moves briskly, so the pressure pulse is steep but farly narrow. Forget about acetylene - it is with good reason in a class by itself! If you look at the area (energy) under the pressure pulse, it is phenomenal, and it's tendancy to self-ignite (unless compressed under special atmosphere) levels cheapskate shade-tree mechanic garages every year - it's a Darwin thing. I hope this was what you were looking for. The code books tell about what flammables are in which groups classes, but they do not tell about the tests. Check out UL 698 for containment-type enclosure testing methods. Intrinsically safe is a low-energy ignition-prevention method for haz loc, but that is another story. Mike Harris/Teccom - Original Message - From: richwo...@tycoint.com To: emc-p...@majordomo.ieee.org Sent: Monday, February 04, 2002 7:59 AM 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 Healddavehe...@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
RE: Haz Loc Testing
You may also want to contact Factory Mutual (Norwood, MA), they are heavily involved into intrinsically safe and explosion proof equipment testing/approvals. Leo Simon EMC Corp. -Original Message- From: cnew...@xycom.com [mailto:cnew...@xycom.com] Sent: Monday, February 04, 2002 1:05 PM To: emc-p...@majordomo.ieee.org Subject: Re: Haz Loc Testing If you're serious about haz loc then I suggest that you purchase the following book from http://www.nfpa.org/Catalog/ Electrical Installations in Hazardous Locations -Carl From: richwo...@tycoint.com on 02/04/2002 10:59 AM Please respond to richwo...@tycoint.com To: emc-p...@majordomo.ieee.org cc:(bcc: Carl Newton/XYCOM) 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 Healddavehe...@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 Healddavehe...@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 Healddavehe...@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.
Re: Haz Loc Testing
Hello Rich, If you visit the Safety Link www.safetylink.com and then search for the term hazloc using your browser's Find function (often Control F), you will find 3 adjacent links to very good resources on this topic. Immediately below those links you will find one on Intrinsic Safety, a closely related subject. Regards, Art Michael Int'l Product Safety News A.E. Michael, Editor 166 Congdon St. East P.O. Box 1561 Middletown CT 06457 U.S.A. Phone : (860) 344-1651 Fax: (860) 346-9066 Email : i...@safetylink.com Website: http://www.safetylink.com ISSN : 1040-7529 - On Mon, 4 Feb 2002 richwo...@tycoint.com wrote: 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 Healddavehe...@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 Healddavehe...@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.
Re: Haz Loc Testing
If you're serious about haz loc then I suggest that you purchase the following book from http://www.nfpa.org/Catalog/ Electrical Installations in Hazardous Locations -Carl From: richwo...@tycoint.com on 02/04/2002 10:59 AM Please respond to richwo...@tycoint.com To: emc-p...@majordomo.ieee.org cc:(bcc: Carl Newton/XYCOM) 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 Healddavehe...@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 Healddavehe...@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.
RE: Haz Loc Testing
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 Healddavehe...@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 Healddavehe...@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.
RE: Haz Loc Testing
Richard, One good preliminary source of reference is NEC Article 500.provides a breakdown of the various classifications of Haz Loc environmentsfrom there on in, it's a matter of selecting the appropriate product safety standard to meet the implementation as well as the equipment. Regards, Kaz Gawrzyjal kazimier_gawrzy...@dell.com -Original Message- From: richwo...@tycoint.com [mailto:richwo...@tycoint.com] Sent: Monday, February 04, 2002 10:00 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 Healddavehe...@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 Healddavehe...@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.
