Chuckles —

I am insulted that you think that I over-insulted you, vis-vis Jer. Harummph.

Actually, I insulted him first, by saying that I wouldn't build that air system his way.

However, it's all a matter of risk/reward. Jer is a blind guy; a multiple amputee and multiple transplants. He can afford to take more risks that I wouldn't.

I would probably build such a system much as you describe above. But I wouldn't put a double-block-and-bleed on the filter. Actually, in refinery practice, where every minute of down-time translates to big bucks, redundant filters w/ beaucoup blocks and bleeds. But, in my garage, I would merely turn off the compresor to change the filter.

Also, you ask: « How in the blue blazes do you change out a control valve without spilling the entire, sometimes very hazardous, almost always highly flammable contents of both ends of the piping out onto ground underneath the mechanics without a double block and bleed. » ??

First, note that I was talking pilot plant design, which should, but often doesn't, have a different set of design criteria. In a pilot plant, one can specify a valve w/ a mechanical over-ride. Then, one can easily shut down the facility, drain the lines, and perform manitainance. See? Different set of criteria for pilot plant design. Similarily, one doesn't have to design for 20-year life when the facility probably won't operate 2000 hours in its entire lifespan.

Another example of the home, vs. the refinery: Does the wiring in your home in West Texas run in thin-wall conduit. In a refinery it would, in a non-hazardous area. Do you have natural gas in your home? Then, your wiring should be Class I Grp D (That's explosion-proof code, to those non-chemical types), with heavy-wall conduit and asphalt seals at each end of a run.

Well, my home is in an area that is prone to flooding and also power failures. The previous owner had installed battery-operated back-ups on both sump pumps. Now, batteries can give off hydrogen during charging, under certain conditions. Did that owner rip out the wiring and install Cl I, Grp B wiring? Nope. Not cost-effective. Well, wouldn't you know it, the battery in the furnace/water heater area blew up last week. What a mess! Acid — 6N sulfuric acid — everywhere. Cost me $1300 to replace that system. But still cost-effective to replace, rather than put in the explosion-proof wiring.

My moral here is — to think!! To put brain in gear before typing. Refinery standards are great. But they don't necessarily extrapolate to pilot plant design and operation, nor to the home.

GEEZER



[Modified by OlGeezer, 2:34 PM 11/13/2001]

 

GGGRRRRRIIIIINNNNNDDDDDD...BZZZABZZZZABZ ZZZ...GGGRRRIIIINNNDDD...KACHUNK!!!!! Whew, gettin' tougher to git dat ole mind in gear!!! :jester :jester :jester

Geezer, iffn' it wuz me, I wud git dem dam battries dat arts and science major put in dere OUT, OR I would get me some dang TEFC (dat's 'Totally Enclosed Fan Cooled' fer youse uneneeshated) motors for dem dam sump pumps (an' don't fergit the furnace blower motor). But, dem dang TEFC motors is prittee dang hard to find in frachunal horsepower, yawl will have to trust me on dis'. Oh yeah, an' don't fergit to tell duh wife dat the basement is uh "No Smokin'" zone.

Hey, Geezer??? Look heah now! Have you inspected duh nails in yo' floor joists?...that dang sulphuric acid might have eaten dem away right thru the wood an' put yo' whole house in danger of collapse befo' duh explosion. Dat way you cud look at dis' explosion and duh mess as kinduva' blessin'...a "wake-up call" so to speak.

You wuz speakin' of gas pipes...I believe I wud git me one of dem enspectors out dere to measure yo' gas pipes remaining wall thickness wid' one of them radio-graphy machenes...dat sulfuric acid is bad stuff, you know? :jester :jester :jester