AIR TANK BOMB

J

jim wagner

New member
Nov 13, 1999
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Tom, When I made the PVC air tank I installed the presure relief valve.
If this valve has vented because of a pressure increase I don't know.
But that is what it is for. I believe that the pressure rise is 2.5
psi. for every 10 degree Fahrenheit. This would be only 25 psi for 100
degree rise.
I am thinking of adding another tank with a shutoff to use in case my
air system fails. When I get done adding air tanks I will be able to
float our GMC down the Mississippi.
The other Jim 76GB 500Cad
 
why mess around with compromises - just go down to the auto parts store
- - buy a 3-5 gallon metal air tank rated at 125 lbs with lots of reserve
- - find a mounting point and mount it permanently in the GMC - adjust the
connectors to whatever you need - safe, secure, and not much larger than
a big battery
- --

ron keener near Austin, Texas http://MidAmericaBreedingTech.com
**************************************************************
* proud owner of classic 1978 GMC Birchaven motorhome
*
**************************************************************
 
I really know better than to do this, since I'm jumping in the middle of the
thread without reading all the preceding posts, but hey!, why not...

>
> PVC has a rather large coefficient of expansion and
> contraction. Usually what happens the Pvc expands
> as the temp rises. The higher the ambiant temperature,
> the hotter the air tank.

> Is 180 degrees a high enough figure for this
> discussion.

Yep, IMO.

> If this tank was in the engine compartment at 230
> degrees, what are those maximum pressures?

Whoa! Where did that number come from? We discussed engine compartment
fire supression systems a few months back and I thought we had settled the
fact that the engine compartment would rarely exceed 200 degrees and that a
220 degree device actuation temperature was appropriate.

Also, why in the world would you mount an air tank in the engine
compartment? It's already too crowded in there and there's no compelling
reason for the tank to be there. I'm thinking of moving the whole system
rearward to find a more hospitable environment and replacing my PowerLevel
valves with microsolenoids mounted near the tank - but that's another story
and I've got plenty to do before I get there.

> This topic should be discussed more!

Agree! Carry on...
Patrick
 
Or buy one of Jim Damaere's beautiful stainless steel tanks.

>
> why mess around with compromises - just go down to the auto
> parts store
> - buy a 3-5 gallon metal air tank rated at 125 lbs with lots
> of reserve
> - find a mounting point and mount it permanently in the GMC -
> adjust the
> connectors to whatever you need - safe, secure, and not much
> larger than
> a big battery
 
I looked in my McMaster-Carr catalog, and found the following:

- - 4" PVC Sch. 40 white pipe, max. working pressure 220psi based on water at
73 degreesF, derate 50% at 110 degreesF, and 78% at 140 degreesF, maximum
temperature rating 140 degreesF, not recommended for compressed air or gas
systems.
- - 4" PVC Sch. 80 gray pipe, max. working pressure 320 psi based on water at
73 degreesF, derate 50% at 110 degreesF, and 78% at 140 degreesF, maximum
temperature rating 140 degreesF, not recommended for compressed air or gas
systems.
- - 4" CPVC Sch. 80 light gray pipe, max. working pressure 320 psi based on
water at 73 degreesF, derate 23% at 100 degreesF and 50% at 140 degreesF,
maximum temperature rating 140 degreesF, not recommended for compressed air
or gas systems.

Robin

> ----------
> From: tom warner[SMTP:warner]
> Reply To: gmcmotorhome
> Sent: Monday, April 17, 2000 10:04 AM
> To: gmcmotorhome
> Subject: Re: GMC: AIR TANK BOMB
>
> Jim its not the pressure in the tank that I am worried about. If it
> contains
> 150psi and the PVC is rated at 220PSI at 72F than what is the rating in
> PSI
> at 180F? That might be the problem in which case the relief valve would
> do
> no good.Something that someone should at least look at. Normally one
> engineers a system for at least 100% at the worst case.
>
>

> >Tom, When I made the PVC air tank I installed the presure relief valve.
> >If this valve has vented because of a pressure increase I don't know.
> >But that is what it is for. I believe that the pressure rise is 2.5
> >psi. for every 10 degree Fahrenheit. This would be only 25 psi for 100
> >degree rise.
> >I am thinking of adding another tank with a shutoff to use in case my
> >air system fails. When I get done adding air tanks I will be able to
> >float our GMC down the Mississippi.
> >The other Jim 76GB 500Cad
> >
> >
> >
>
 
For $60 for a new stainless one, I am not sure it needs too much discussion.

gene

>
>PVC has a rather large coefficient of expansion and contraction. Usually
>what happens the Pvc expands as the temp rises. The higher the ambiant
>temperature, the hotter the air tank. I think what will happen with PVC is
>that it will NOT be rated for 220 lbs, It will be something less. At what
>temperature does it expand so much that the pop off valve starts leaking? I
>don't know. Is 180 degrees a high enough figure for this discussion. If
>this tank was in the engine compartment at 230 degrees, what are those
>maximum pressures? This topic should be discussed more!
>
>Scott NEHODA'S
>BACK YARD
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/
 
Tom,

That's not an answer, it's an excuse.

Patrick

>
> And to answer
> another question why would you install the air tank in the engine
> compartment? Thats very near where my original one is, adn
> very close to the driver side header.
 
Nope, I want to move the entire system, not just the compressor(which is
exactly what GM did with ELII).

Patrick

>
> What do you mean an excuse. Thats where GM located it. You
> want to move the
> air tank away from the air pump just to save a few dollars on
> an air tank
> and add to your personal risk. Dont think so. With this kind
> of mentality
> you are courting disaster.
>
>
>

> >Tom,
> >
> >That's not an answer, it's an excuse.
> >
> >Patrick
> >
> >

> >>
> >> And to answer
> >> another question why would you install the air tank in the engine
> >> compartment? Thats very near where my original one is, adn
> >> very close to the driver side header.
> >
> >
>
 
> Hi Patrick!
> I thought I have read where some have put these tanks in the engine
> compartment, maybe I am mistaken.

Second generation Power Level(75 & later??) had the tank mounted beside the
compressor on the drivers side near the radiator. First generation had the
tank mounted under the battery tray(neat idea, eh? - mount a mild steel tank
where battery acid can drip on it...).

> I haven't decided yet what the engine compartment temps are
> in the real world. Waiting for some actual on the road
> guys to get back with the numbers.

There were some "real numbers" posted here in the original discussion of
fire supression systems. Ed Kremer maybe??

> We now the engine is around 190, add the exhaust, 230 isn't
> out of the question.

IMO, it is.

> I personally think the engine temps can get higher than 230
> under certain conditions

C'mon Scott, this is just a baseless assumption. :)

Keep smilin',
Patrick
 
So we should only follow GM's lead if you agree with their decision? When's
your book gonna' be published?

AFAIK, the only real problem with the EL system was that GM installed the
solenoids backwards.

Patrick

>
> yes they did and made the system worse. I would not trade one
> power level system for 10 electrolevels.
>
>

> >Nope, I want to move the entire system, not just the
> compressor(which is
> >exactly what GM did with ELII).
> >
> >Patrick
> >

> >>
> >> What do you mean an excuse. Thats where GM located it. You
> >> want to move the
> >> air tank away from the air pump just to save a few dollars on
> >> an air tank
> >> and add to your personal risk. Dont think so. With this kind
> >> of mentality
> >> you are courting disaster.
> >>
> >>
> >>

> >> >Tom,
> >> >
> >> >That's not an answer, it's an excuse.
> >> >
> >> >Patrick
> >> >
> >> >

> >> >>
> >> >> And to answer
> >> >> another question why would you install the air tank in
> the engine
> >> >> compartment? Thats very near where my original one is, adn
> >> >> very close to the driver side header.
> >> >
> >> >
> >>
> >
> >
>
 
>
> Second generation Power Level(75 & later??) had the tank
> mounted beside the compressor on the drivers side near
> the radiator.

Whoops! That was the ElectroLevel I that replaced the Power Level around
75.

Patrick
 
Tom,

Note the "??", meaning I wasn't sure when the change took place. Also,
"early 76" would be 1975 manufacture, especially considering the slow
completion rate. Often the title's and VIN's don't agree.

BTW, my father's 76 Eleganza has ELI and it functions flawlessly. Hasn't
given any problems at all in the five years he has travelled over 35,000
miles with the coach.

Patrick

> -----Original Message-----
> From: tom warner [mailto:warner]
> Sent: Monday, April 17, 2000 11:51 AM
> To: gmcmotorhome
> Subject: RE: GMC: AIR TANK BOMB
>
>
> Sorry again patrick but early 1976s had the powerlevel not
> electrolevel.
>
>

> >>
> >> Second generation Power Level(75 & later??) had the tank
> >> mounted beside the compressor on the drivers side near
> >> the radiator.
> >
> >Whoops! That was the ElectroLevel I that replaced the Power
> Level around
> >75.
> >
> >Patrick
> >
> >
>
 
>
> Not at all.The power level system is simple and almost
> foolproof.

Actually, it's neither. Almost fifty feet of nylon tubing strung out along
the coach and prone to leak anywhere along that length. Original control
valves that leak like sieves(porous castings! another wonderful example of
GM lack of ability to execute the design). Controls that are
counter-intuitive and difficult to reach from the driver's seat.

> Why go to a more complicated system like the
> electrolevel? What did it accomplish?

Well, the only way that the system I'm considering would be like the EL is
that it would use electricity and solenoid valves. Also, I'm thinking that
a CD changer might fit nicely in the dash space I'd free up.

Patrick
 
You're right as always Emery. Dad's 76 also has the tank and compressor in
the cabinet. Maybe there was a second generation Power Level. I know the
tank was relocated somewhere along the line. My 73 VIN is in the 500's and
it had the tank under the batteries. Wonder when it moved?

Patrick

> -----Original Message-----
> From: EMERYSTORA [mailto:EMERYSTORA]
> Sent: Monday, April 17, 2000 12:06 PM
> To: gmcmotorhome
> Subject: Re: GMC: RE: AIR TANK BOMB
>
>
>
> In a message dated 4/17/00 3:09:57 PM,
> Patrick.Flowers

>
>
> Second generation Power Level(75 & later??) had the tank
> mounted beside the
>
> compressor on the drivers side near the radiator. First
> generation had the
>
> tank mounted under the battery tray(neat idea, eh? - mount a
> mild steel tank
>
> where battery acid can drip on it...). >>
>
> The 1977 with ElectroLevel I had a small steel tank located
> in the closet
> across from the bath with the Dana compressor. There is no
> tank up front.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
>
 
Ours is a 77PB built in Oct.76 VIN #372
The compressor and small tank Elect level 1 are in a bottom cupboard across
from Refrigerator- Bath #3 floor plan
Marlene Meineken

- ----- Original Message -----
From: tom warner
To:
Sent: Monday, April 17, 2000 9:21 AM
Subject: Re: GMC: RE: AIR TANK BOMB

> Mine is a 1976 Palmbeach with powerlevel vin #476
>

> >In a message dated 04/17/2000 11:12:37 AM Central Daylight Time,

> >
> >> My 73 VIN is in the 500's and
> >> it had the tank under the batteries. Wonder when it moved?
> >>
> >Patrick
> >
> >My 76 was made Nov 75. I have Power Level. Air tank is the large one
> >mounted on drivers side along with compressor.
> >
> >Take Care
> >Arch
> >
> >
>
>
 
>
> I don't think the normal max operating temp is the concern.
> What happens when your radiator leaks and you don't notice until
> the engine quits ?

That actually won't increase underhood temps as much as you'd think and, in
that event, the air tank will rank very small on your list of worries.

I guess that I should clarify that I'm not advocating a PVC pipe air tank
although I did consider the option a while back. I just don't like the
misinformation on underhood temps.

Patrick
 
I guess as long as you have lots of O rings and remember the difference
between Vaseline and putty.

gene

>
>> I would not trade one power level
>> system for 10 electrolevels.
>
>Tom,
> I'll agree with you 100% on that one. (You all may want to note this
date
>for posterity. I seldom agree with myself 100%.) ;-)
> As for the PVC tanks pro and con: since they're mounted under the floor
>and shielded from passers-by, I think the odds of injury or serious
colateral
>damage is slight even if one should explode. Why not present the
>specifications (gleaned from the industrial supply catalogs), offer a word
of
>caution, and see what people's experience is? Apparently some have been
>using such tanks for years. Any failure reports?
>
>Rick Staples
>'75 Eleganza
>Louisville, CO
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/
 
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