Jon,
Maybe I am wrong but wouldn't the following line be different.
Patomoshpere * Vatmoshpere = Psystem * Vsystem
1 atm * 23 in^3 = 7.85 atm * Vsystem
Vsystem = approx 3 in^3 : this is the volume of air the cylinder
volume
I think that Patmosphere would be 1 atm, Psystem would be 7.85, BUT Vsystem
would be 23 in^3 and Vatmosphere would be 180.55???? (Not 3). That might throw
a wrench into the plan.
Anyone??
Jamie
-----Original Message-----
From: Jon Garruba [SMTP:jgarru01@longisland.poly.edu]
Sent: Tuesday, January 04, 2000 5:21 PM
To: K M
Cc: Bricklin@autox.team.net
Subject: Compressed Gas for Air Doors
Has anyone ever used a high pressure compressed gas tank, like used for
welding gasses, for the air doors? on a separate is it possible to bend
the door hinges or roof with too much pressure in the system? if so what
is the max pressure that can safely be used. My hoses are rated to
150psi and I used up to 140psi but never held the button with the door
fully up. Is it possible to damage the car like that?
Anyway back to my original reasoning.
I'm sick of my cheesy electric air compressor! I'm planning on adding a
high pressure tank to the system to give it a quick charge when needed.
I did some calculations and I figure I would get about 200 door openings
per charge. it works out to be about about $.01 per door opening given
the right equipment. and an air leak free system.
I know there are some engineers on this list. could one of you check
over my calculations. I don't want to put this thing together and find
it costs me $10 to open my doors twice! I'm an electrical and computer
engineer mot a mechanical one. Even though this stuff is basic It cant
hurt to be sure.
1 ft^3 = 1728 in^3
1 atm = 14 psi
I was planning on using a 20 ft^3 air tank readily available from
welding supply stores. Regulated to about 110psi. And adding another
solenoid to switch the high pressure compressed tank to charge the
standard low pressure ones, as a back up for the electric compressor.
This is what I came up with
20 ft^3 = 34560 in^3
The volume of the pneumatic cyl: Vcyl = pi * r^2 * h
diameter of cylinder = 1.5"
height of cylinder is approx 13"
Vcyl = 3.14 * .75"^2 * 13" = approx 23 in^3
I plan to run the system at 110 psi. That seems to be a good measure
for the drivers door. the passenger door works fine at 100, but the
drivers side needs higher pressure I guess its wearing out.
110 psi = 7.85 atm
Neglecting error from temperature change.
Patomoshpere * Vatmoshpere = Psystem * Vsystem
1 atm * 23 in^3 = 7.85 atm * Vsystem
Vsystem = approx 3 in^3 : this is the volume of air the cylinder
volume
would be at 110 psi
Vcyl / Vsystem = 7.66 : The # of Vcyl at 1 atm which compress to 1
Vcyl at 110psi
Vcyl * 7.66 = 176in^3 : the volume of air at 1 atm which occupies
Vcyl at 110 psi
20 ft^3 / 176 in^3 = 196 : door openings
$36 for 300ft^3 of compressed nitrogen. I plan to transfer the gas from
a large 300 cubic foot tank to the smaller 20 cubic foot tank
personally.
300 ft^3 = 518400 in^3
518400in^3 / 176 in^3 = 2945 door openings per refill of large tank
approx 1.2 cents per door open.
I might have been able do it simpler, but that's from memory. Any input
or ideas on the subject would be greatly appreciated. thanks
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