Tony : The nozzles you refer to being all plastic , and as such subject to excessive wear. The whole idea of the self cleaning is it requires pressure to push the inner portion of the nozzle which forms the orifice when operating into proper position. When pressure is removed the inner portion springs back and opens . First this takes force. Second you have moving parts , if you have moving part you have friction and an area of close fit where fine particles can lodge or wear the mating surfaces. I never had any luck with them for consistent spray patterns and or droplet size, and when the solution got loaded , they still clogged. If I was going to use them today , it would be in a water rinse section only. and only then if I didn't have conventional nozzles. They would be great in very large sizes for cleaning tanks, or quenching steel and such where you couldn't afford to have a clogged nozzle. My experience is that you will get the most for you buck if you spend money on positive filtration systems for the equipment in question. Bag, or plate housings are the best for high flow rates. cartridges are readily available and easy to change. What ever form you pick , you will find that with a good positive filtration ( ie one that all of the solution must pass through) consistency of process is improved and some defects are diminished.) Just think about it , take a developer for example , most have only a window screen to keep the chunks out , but yet we deal with features considerably finer than the mesh. Just for your information , I recommend a maximum filter size of 0.5 of the nozzle orifice diameter, or the smallest geometry to be processed which ever is smaller. Thus if you have a developer with say Spray Systems HVV 5005 nozzles ( 50 degree , 05 orifice size ) , the Equivalent orifice diameter is 0.057" or about 1400microns divided by 2 for a filter size of 700 microns, since for example I want to clear holes say 0.010" ( 250 microns ) , then I want a filter 250/2 =125 or the next common size 100micron. With any given nozzle size, if you increase the pressure you decrease the droplet size, improve the spray pattern, velocity, and impact. the same is true as the solution rises in temperature. the item that will degrade the effects of pressure and decrease spray pattern, velocity, impact and increase droplet size is an increase in viscosity. Hope this helps , If you need further assistance let me know Russell Smith [log in to unmask] ---------- From: Tony Steinke To: [log in to unmask] Subject: [TN] SPRAY NOZZLES Date: Wednesday, September 27, 2000 10:24AM Good day fellow technetters, We are a manufacturer of PCB's.I am currently in the process of replacing old, worn nozzles in several areas of the wet process area and was wandering if anyone out there has had any experience with self cleaning nozzles from a manufacturer called Laidler. My question is are they really self cleaning or am I throwing money into a product for no reason for the nozzles are quite a bit pricier than original equipment manufacturer. Any input would be greatly appreciated. Tony Steinke Process Engineer [log in to unmask] Circuit Technologies 3622 Clearview Parkway Atlanta, GA 30340 (770) 458-1700 www.cir-tech.com ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8d ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################