SW 4.0 Compressor Question. Pescador ?

[2859tim]

Hi ,

I am new to scuba board & have monitored posts on SW & Kiddie portable compressors for several years and wanted to thank all of you for taking all the time to educate us !

The technical discussions & background are really impressive & I have learned alot. Especially posts from pescador as he removes alot of confusion & myth !

I have a 1978 Stewart Warner Southwind 4.0 CFM 3 stage direct drive Portable compressor I will use for boat diving. I have only seen a few of these units ever and they appear to be a full SW factory platform specifically for breathing air. Uses a Kohler 7.5 Gas motor, SW condenser with Adjustable relief, Norman 4500 Filter housing I pack with tri-mix and Circle Seal adjustable relief at output as 1800 PSI priority valve. I have no literature, but the name plates actually call it as breathing air compressor.

Do anyone know any background on these ?
Is Jet 11 still the recommended oil and not chem lube 201 for breathing application in SW compressors ?

I think I remember Gunner Alfter down in LA telling me (Years ago) that these SW final stages (at pressure) should be hand touchable ? but mine is too hot..I have not IR read the final stage output yet, however, if I go by the old rule of thumb "If you can you hold your hand on metal for 8 seconds it's less that 140F" then I am exceeding 140 by some degree.

Should I be concerned about this temp ?

Thanks kindly for any advice...Tim in Ca.

 

[pescador775]

Tim, it seems you have the Navy EOD portable compressor. The teams which consisted of detachments of three or four men used these for refilling their SCUBA bottles during the course of normal duties like recovering spent ordnance. The factory units usually installed a SW coalescer and no filter. It may be that the filter on your machine was added later. Originally, lubrication consisted of medicinal grade mineral oil. For extreme low temps, aircraft instrument oil was used if available. The mineral oil was used because it is presumed to be non toxic. Your system should do fine with JET II oil while operating in the ambient range of 0F-100F. This is the same oil currently recommended by Meggitt Airdynamics for their Kidde pumps and is a really advanced lubricant. Stewart Warner did not mention this oil possibly because the old JET II was of medium toxicity and a manufacturer of breathing air compressors had limited selections available back in the day, eg, lubricants suitable for extreme conditions and 3500 rpm. On the other hand, the Kidde was never used for breathing air except as retrofits so breathing quality was not a consideration. Following some well publicized statements by pilots who complained of "fumes" in the cockpits of some aircraft, Exxon/Mobil finally said "to heck with all this crap" and pressured their suppliers to produce non toxic additives in which their chemists were successful.

I can't comment of the temps of the cylinder heads except to say that I would be surprised if you could hold a finger on a cylinder head for more than a few secs. Normal temps should be in the range of 140-150F. If air temps are above 80F do not operate the machine in direct sunlight. Ensure a good flow of air to intake and to fan.

 

[2859tim]

Wow...Thanks for fast comeback on History, Oil & Temp.

Yes, i think your correct on the after filter being an addition. When I got this unit, It appeared to be brand new & not run before. Came with Whip, Remote Fuel tank, ect.

I have about 9 tank fills of runtime todate & am only getting 3.48 CFM out of it ?

Have leak checked as best as I can & can't find reason why. I'm running the motor at max throttle where governor dominates RPM. I'm going to put strobe the motor and wondering if it's correct to expect that motors loaded RPM should match the max nameplate RPM on the Compressor ?


Also..Are the same Pesky that is on Iboats responding to Volvo technical questions ?

 

[pescador775]

Yeah, but I'm the pesky on Marineengine.com. Are you a Volvo man, too? Got twin 4 cyl OHC in my boat. Haven't been on that site for awhile. I run hot and cold on stuff. When I get bored with the board I'm history. Kinda stuck around this place, hopefully not too long.

The engine might be running slower than spec. Should be turning 3400-3500 revs.

 

[2859tim]

I thought so....Yes, I'm a Volvo dude also. I have owned & rebuilt quite few different IO packages over the years, from Merc, OMC, Volvo & love the Volvos best....I also have twin 2005 3.0/SXs in my latest dive boat refit project, skipjack 25 hardtop. Great little gas efficient packages. Only problem is the California Air Resource "CARB" modification on the carburetor idle circuits ! Hurts far more than it fixes, if you ask me.

I have followed your posts alot..You are one heck of a mechanic !


I'll get on the RPMs...Thanks again..Cheers !

 

[pescador775]

You're welcome, Tim. Here is some misc info on the Navy divers' compressor:

"Compressor Package Assembly"
MODEL 3800203-5
FSN 2H4310-165-4885
Service Manual, NAVSHIPS 0994-011-9010

Sorry, don't have the above manual available but there are several generic manuals for the 4cfm being offered on CD.

Pesky

 

[2859tim]

Starting to look into the seveal suggestions (above) to find rootcause of reduced CFM i am experiencing (3.48CFM when should be 4.0). One items is that my filter application is a T style Norman 4500 housing with 5000 PSI rating where I have converted to be repackable type. That means that i am inputting compressors post separator 1/4" line into the bottom of the norman filters bowl for upflow through entire bowls volume and top heads input port plugged . The fitting at the bottom of the bowl was originally configed as a drain port so is 1/8" NPT.

I'm wondering if the 1/8" neckdown is limiting my final CFM to something less than 4.0 ? or can 1/8" handle 4,0 cfm ?

If it is clearly an issue, i would plan to drill out & tap the Norman filter bowls bottom drain for 1/4" fitting. Bowls bottom has substantial flange with thick walls so looks like it would have no problem supporting increased diameter fitting for my max PSI application at 3450?

Any advice is greatly appreciated..Tim in Ca.

 

[pescador775]

The 1/8" port is irrelevant in this compressor. High pressure gas will flow through very small orifices unimpeded. If there is a more serious restriction somewhere the relief valve will be leaking gas. Check engine revs and review your test method. Engine RPM should be 3400-3500. Pressurize the entire filtration system to 3000 psi, open fill cock and then the tank valve and immediately start the count. The only other explanation that I can think of is leaks, either system tubing and fittings or rings. The most common leak is the drain spigot. Blowby can be measured at the vent. Remove the cap and place hand on vent and be alert to gas flow at various pressures. If flow is detected, some kind of DIY rig to measure the actual amount may be needed. This would require a 1 cfm flow meter and some kind of jerry rigged fitting on the vent. If flow was originally found to be light this may not be necessary. If large flow and oil mist exits the vent there is a possible problem and only measurements will confirm or deny.

I'm not familiar with the Norman. What are filter bowls?

 

[2859tim]

Thanks Pesky,

I had not even considered checking the vent for blow-by + will check the SW moisture seps relief for leakage also. i have a small gas flow column so should not be too hard.

The norman 4500 T filter is a blue anodized Aluminum bowl with 5000 PSI working pressure and I'm told it's a typical 4 to 1. Bottom bowl has a 1.5" Hex protrusion that is used to torq the bowl to the head with o-ring seal at 30 ft/lbs. In the center of this feature is the factory 1/8" NPT port and these same exact bowls are also available with 1/4" drain, so I'm thinking it must be OK to drill & tap my own 1/4" if needed. But since the 1/8" is OK for 4.0 cfm then I'll plan to stick with existing ports since they are done and plumbed presently.

Sorry...Tried to post Norman 4500 URL but site requires me to have more posts before hand

 

[pescador775]

No problem, I googled it up. The Norman is a hydraulic filter consisting of a canister and filter head. There is an internal paper filter. Looks pretty good for DIY drier, purifier project.

The SW blow by vent is so large it may be difficult to estimate flow. Suggest that you insert a plug with approx 5/16 inch hole to throttle down the flow. If there is a large flow, screw a tube into the plug and hook up the flow device with a piece of hose or tube. It does not have to be fancy. However, If your flow tower fills up with oil then it may be necessary to install some kind of damper. There are various ways and means, I insert a small pressure vessel(old Bauer coalescer) in line between the vent and meter which catches the oil.