Compressed Air Supply - Page 1
Forum section: electronics / general

author: blacksheeplogic
author_rank: Frequent Contributor
timestamp: March 15, 2016, 12:16:42 am
content: About a year go we decided to purchase equipment that uses external air rather than internal pumps. Some equipment is either not available with internal pumps or is significantly cheaper with the external air option.Initially we installed a refrigerant air dryer with a 0.2 micron inlet filter and a 0.01 micro outlet filter prior to the manifold. The compressor was an oil-free design and there's about 75ft of 1/4" air hose prior to the refrigerant dryer and another 15ft of air hose after the dryer before the manifold which provides the 6mm connections we need. The system runs at 85 psi.The compressor was unable to meet the air requirements and we replaced it with a twin compressor that has an oil sump and added a 1 micron carbon coalescing filter close to the compressor (15ft of air hose pig tail prior to the filter and the filter then connected into the main air line).It's recommended to install a general purpose 5 micron filter prior to the carbon coalescing filter in the system. While a good idea I'm not overly concerned about having to replace the carbon coalescing cartridge more frequently as they relatively cheap but I am concerned about oil in the line making it's way into the system.Anyone else using a oil sump air compressor and what size/type of filters are you using both prior to and after the refrigerant dryer?

author: uncle_bob
author_rank: Unknown
timestamp: March 15, 2016, 12:58:15 am
content: Quote from: blacksheeplogic on March 15, 2016, 12:16:42 amHiThe classic answer to oil is a cold trap. The other answer is to not use an oil pump.Bob

author: blacksheeplogic
author_rank: Frequent Contributor
timestamp: March 15, 2016, 03:17:38 am
content: Quote from: uncle_bob on March 15, 2016, 12:58:15 amThanks Bob,The refrigerated air dryer I have is a cold trap so I guess the better question is what temperature is needed to separate the oil vapor from the air supply do you know? I'm not an expert in this area and it's not clear what the condensation point of the oil in the compressed air supply would be from the documentation I've seen.I agree an oilless compressor would be a better option but a rotary compressor is a significant investment.

author: DTJ
author_rank: Super Contributor
timestamp: March 15, 2016, 03:22:24 am
content: Not contaminate related but with 75ft of 1/4" line to push through, perhaps the original compressor was fine and the flow was limited by the 25 metres of 1/4" line.

author: thefamilyman
author_rank: Regular Contributor
timestamp: March 15, 2016, 03:34:59 am
content: hibeing in the compressed air industry i can help you.Depending on what the air is used for dictates what filters you should use.for example, food industry we would use a rotary screw compressor with food grade oil, then into a 1µm then a 0.01µm filter then into refrigerated dryer, then into carbon filter then another 0.01µm to remove any carbon dust.for laboratory situations we would use the same as above but with an oil free scroll compressor or oil lubricated scroll.just a concern, 1/4" line would seriously limit the air flow.

author: IanB
author_rank: Super Contributor
timestamp: March 15, 2016, 03:41:21 am
content: Quote from: blacksheeplogic on March 15, 2016, 12:16:42 amQuoteWhat was the air requirement? It is possible to calculate the pressure loss in the air hose given the required flow of air.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: March 15, 2016, 06:07:10 am
content: Quote from: blacksheeplogic on March 15, 2016, 12:16:42 amAnd exactly how is this related to Test Equipment, and why could this not have gone in 'Other Equipment' where it would actually been on-topic?@Mods: please move to this thread to the right sub-forum

author: CustomEngineerer
author_rank: Frequent Contributor
timestamp: March 15, 2016, 06:26:32 am
content: I don't know, I've found that 90 or so psi from my compressor through a short piece of hose and into my scope tends to help maintain the temperature and keep me from having to run a self cal every 30 minutes. And since its a Rigol scope it doesn't really create any extra noise. The only issue I've had so far is getting oil into my scope, so this discussion interests me.

author: blacksheeplogic
author_rank: Frequent Contributor
timestamp: March 15, 2016, 07:04:31 am
content: Quote from: thefamilyman on March 15, 2016, 03:34:59 amThank you for reply. I will order the two additional filters and change out the first filter cartridge.The 1/4" hose was supplied with the system, interesting all the couplers had 1/4" to 1/2" adapters installed. We just used what we got initially.

author: blacksheeplogic
author_rank: Frequent Contributor
timestamp: March 15, 2016, 07:06:55 am
content: Quote from: Wuerstchenhund on March 15, 2016, 06:07:10 amA mistake was made.

author: blacksheeplogic
author_rank: Frequent Contributor
timestamp: March 15, 2016, 07:15:00 am
content: Quote from: CustomEngineerer on March 15, 2016, 06:26:32 amHmmmm, you might be surprised by the additional noise. It's quite noticable.....

author: uncle_bob
author_rank: Unknown
timestamp: March 15, 2016, 10:12:47 pm
content: Quote from: blacksheeplogic on March 15, 2016, 03:17:38 amHiIn a vacuum system you often cool the cold trap with liquid nitrogen. That gets the back stream down to pretty low levels. As with anything, it all comes down to "how low do you need?".Bob

author: CustomEngineerer
author_rank: Frequent Contributor
timestamp: March 16, 2016, 04:09:27 am
content: Quote from: blacksheeplogic on March 15, 2016, 07:15:00 amThe Rigol fan is supposed to be quite noticeable as well but I've never heard the fan on mine.

author: Towger
author_rank: Super Contributor
timestamp: March 16, 2016, 04:26:42 am
content: You lot need a real fan, because on the real word the PSI from a Rigol is a toy. What you need is a La Croy, now that's has a real man's fan.