Doctor Mud Posted October 29, 2014 Share Posted October 29, 2014 Hi everyone, I now own a compressor and a couple if air scribes and I'm looking forward to not using engravers anymore. I've never owned a compressor before and wondered whether they should have a structural rating for pressure for the tank. I would assume that the tanks are stress tested in the factory to determine the safety limits. The manual for mine states "working pressure 8 bar" but nothing about maximum working pressure. Not that I'm planning on increasing the pressure, just nice to know how much leeway there is. In case the release valve failed or something. I read that proper industrial tanks should be fitted with a plaque or label with the rating. Maybe not "hobby" compressors. Funny, I rang the retailer and they thought this was an odd question.... They did promise to contact the manufacturer though. Thanks guys for listening to my safety concerns. Link to comment Share on other sites More sharing options...
CH4ShotCaller Posted October 29, 2014 Share Posted October 29, 2014 Mine has a regulator that I adjust frequently. I installed a 'bowl filter' downstream of reg at the hose attachment to separate/remove water. It has an automatic cut off at 150psi and on @ 120psi. The pop safety disc is at 200psi. Other than adjusting the reg, I don't think (based on my system) there's another way.. or would I want to do anything. A friend had his explode a few months ago at the weld seam. I keep mine outside when I prep now, it was inside the shed. Anyone who has never made a mistake has never tried anything new. -Albert Einstein Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted October 29, 2014 Share Posted October 29, 2014 pressure vessels have a factor of safety well above the relief valve setting. factor of safety is defined as stress at failure (or perhaps yield) divided by rated stress in normal use, or roughly failure pressure divided by rated pressure. i'm not sure what factor of safety is on a compressor tank design, but i would hope it is at least 4. so if your compressor is rated at 150 psi, i would hope the tank wouldn't fail until 600. in short, you are safe if new and from a reputable mfr. the factor of safety is meant not only to keep your body intact, but also to prevent lawsuits for the mfr (choose whichever motivation suits you best). Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted October 29, 2014 Share Posted October 29, 2014 wow was your buddy's compressor old? i'm wondering if rust took its toll from not draining the tank regularly, or did it fatigue from pressure cycling for years, or whether it had a faulty weld, or if he modified the regulator to achieve higher pressure. i've never known one to pop, and mine has been used hard with a modified regulator for 15 years. Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
Doctor Mud Posted October 29, 2014 Author Share Posted October 29, 2014 I'm with you ShotCaller, I'm working inside and I'm not going to be sitting beside the compressor - chances are it is fine, but I'm not taking the risk even if it is minimal. I'm getting an extension hose and putting the compressor in another room. I thought the working pressure should be well within the actual structural limits of the tank. I was just curious as to why they hadn't listed it in the manual. From what I have read on other forums etc. tanks tend to fail due to rust if they are made by a reputable manufacturer - and then not usually catastrophically. They will develop a hole and won't be able to build up pressure. Didn't want to give everyone the heebie geebies - I just like to know as much about my equipment as I can and the risks involved. Link to comment Share on other sites More sharing options...
tmaier Posted October 29, 2014 Share Posted October 29, 2014 This looks like a useful conversation... http://bbs.homeshopmachinist.net/threads/34475-Best-fix-for-rust-hole-in-air-tank Link to comment Share on other sites More sharing options...
CH4ShotCaller Posted October 29, 2014 Share Posted October 29, 2014 Yes, he bought his a few months after I bought mine, same model, manufacturer, etc. He made no modifications; called me one day and told me it exploded. 2 days later, my water separator exploded. (was my fault, wasn't rated for 135 psi). Anyone who has never made a mistake has never tried anything new. -Albert Einstein Link to comment Share on other sites More sharing options...
crinus Posted October 29, 2014 Share Posted October 29, 2014 I have done everything you should NOT do to a compressor and it has not exploded. I had a compressor that was set at max pressure of 125psi and back on at 90psi. The problem with this was that most scribes stop working efficiently below 100psi. I called the manufacture and the tech told me how to illegally adjust the pressure value so that it filled to a higher pressure and back on at 100psi. I ran it like this for 10+ years with no problem or explosion. A couple of months ago the pressure control developed a leak. A replacement was $120 so I decided to get a new compressor that fills to 150psi and back on at 120psi. Between a sale, a coupon and some negotiation (floor model) I got a new compressor for $225. The other thing that I don't do but should is drain the tank. I would think that rust would be a problem, but my compressor was 20 years old and no problem. It was a brand name machine. Since I use it quite a bit, I would not buy an off brand compressor. crinus Link to comment Share on other sites More sharing options...
jpc Posted October 29, 2014 Share Posted October 29, 2014 (edited) I am also a slacker at draining the water in mine.... : ( Edited October 29, 2014 by jpc Link to comment Share on other sites More sharing options...
tooth_claw Posted October 29, 2014 Share Posted October 29, 2014 Mine has a regulator that I adjust frequently. I installed a 'bowl filter' downstream of reg at the hose attachment to separate/remove water. It has an automatic cut off at 150psi and on @ 120psi. The pop safety disc is at 200psi. Other than adjusting the reg, I don't think (based on my system) there's another way.. or would I want to do anything. A friend had his explode a few months ago at the weld seam. I keep mine outside when I prep now, it was inside the shed. This is very similar to how I run my compressor, the regualtor/filter combo was fairly cheap but totally worth it. The regulator has a dial that lets you know exactly what pressure you are working at. A physical barrier between you and the compressor is a good idea- it also keeps the noise down! Link to comment Share on other sites More sharing options...
Doctor Mud Posted November 6, 2014 Author Share Posted November 6, 2014 Mine has a regulator that I adjust frequently. I installed a 'bowl filter' downstream of reg at the hose attachment to separate/remove water. It has an automatic cut off at 150psi and on @ 120psi. The pop safety disc is at 200psi. Other than adjusting the reg, I don't think (based on my system) there's another way.. or would I want to do anything. A friend had his explode a few months ago at the weld seam. I keep mine outside when I prep now, it was inside the shed. I've been running mine for a few days. Got an extension hose and i run it in the spare room. Might be an idea to install some sort of water filter. My compressor has a moisture trap, but I suspect I'm still getting moisture in the hose and the micro jack is stuttering. I read that putting one in further down the line gives the air a chance to cool and moisture condense. I'm also in Brisbane where it gets humid. What does your bowl filter look like? Does your compressor have a built in trap too? Thanks for helping an air tool newbie. Link to comment Share on other sites More sharing options...
Doctor Mud Posted November 6, 2014 Author Share Posted November 6, 2014 P.s I'm LOVING the new tools. Once I work out the bugs in my system they'll be great. I don't know how I ever put up with engravers for so long. The difference is like night and day. Link to comment Share on other sites More sharing options...
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