When i bought my boat, it was 10 yrs old and even then the fuel
sending unit didn't work. Over the years, I have replaced it 4 times
and it has NEVER worked right. Those damned sending units are such
crappy technology...electrical/resistive/ mechanical/floating going to
a meter, and they really expect this to work for any length of time on
a boat? So....
Useless idea #3741 (I am really going to try this one)

Take two pieces of flexible tubing maybe 1/2" diameter filled with
hydraulic fluid connedcted to a T. The base of the T has a 1/4" clear
hose going up to where it is visible in the cockpit. The two pieces
of 1/2" hose support the fuel tank whose weight compresses the fluid
causing it to rise. As the tank empties, the level in the clear
tubing falls. So, it is really measuring weight. But, no
electricity, no moving parts (except the fluid) and absolute
simplicity. Now, the problem, most fuel tanks are fastened down
firmly so when this thing is installed, it must be able to move a tiny
amount up and down (maybe should use 1/8" clear tubing).

Parallax,
You seem to like figuring out solutions. How about this one.
I have a stainless cylinder 8 inches in diameter, 3 feet high, closed at
the bottom and open on the top.
I want to keep the cylinder filled with liquid nitrogen to within 6
inches of the top and never less than 6 inches from the bottom. I also
want to know when it is half full.
I have a computer with two parallel ports, a solenoid operated cryogenic
valve with an interface to operate from a parallel port, necessary
plumbing to connect to a 1000 gal dewer of liquid nitrogen.
What other parts to I need to fabricate something to measure the liquid
nitrogen in the cylinder.
krj

Parallax wrote:

When i bought my boat, it was 10 yrs old and even then the fuel
sending unit didn't work. Over the years, I have replaced it 4 times
and it has NEVER worked right. Those damned sending units are such
crappy technology...electrical/resistive/ mechanical/floating going to
a meter, and they really expect this to work for any length of time on
a boat? So....
Useless idea #3741 (I am really going to try this one)

Take two pieces of flexible tubing maybe 1/2" diameter filled with
hydraulic fluid connedcted to a T. The base of the T has a 1/4" clear
hose going up to where it is visible in the cockpit. The two pieces
of 1/2" hose support the fuel tank whose weight compresses the fluid
causing it to rise. As the tank empties, the level in the clear
tubing falls. So, it is really measuring weight. But, no
electricity, no moving parts (except the fluid) and absolute
simplicity. Now, the problem, most fuel tanks are fastened down
firmly so when this thing is installed, it must be able to move a tiny
amount up and down (maybe should use 1/8" clear tubing).

Parallax wrote:

When i bought my boat, it was 10 yrs old and even then the fuel
sending unit didn't work. Over the years, I have replaced it 4 times
and it has NEVER worked right. Those damned sending units are such
crappy technology...electrical/resistive/ mechanical/floating going to
a meter, and they really expect this to work for any length of time on
a boat? So....
Useless idea #3741 (I am really going to try this one)

Take two pieces of flexible tubing maybe 1/2" diameter filled with
hydraulic fluid connedcted to a T. The base of the T has a 1/4" clear
hose going up to where it is visible in the cockpit. The two pieces
of 1/2" hose support the fuel tank whose weight compresses the fluid
causing it to rise. As the tank empties, the level in the clear
tubing falls. So, it is really measuring weight. But, no
electricity, no moving parts (except the fluid) and absolute
simplicity. Now, the problem, most fuel tanks are fastened down
firmly so when this thing is installed, it must be able to move a tiny
amount up and down (maybe should use 1/8" clear tubing).


As another said: "Rube"!

We replaced our sending unit with a Snake River metal tank probe. Worked
wonderfully the first year. Didn't the second, but I haven't gotten
around to contacting them about the possible problem from either leak or
our other actions that could affect sensitivity, so can't honestly
complain. The other probes (fresh and waste) have been very useful, so
we're happy.

Flexible tubing gets gunked up pretty easily, so I don't think it would
work very long, even if you substitute hydraulic fluid. The idea of
introducing extra leak points like that is abhorrent to me, though.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

Kelton Joyner wrote in message ...
Parallax,
You seem to like figuring out solutions. How about this one.
I have a stainless cylinder 8 inches in diameter, 3 feet high, closed at
the bottom and open on the top.
I want to keep the cylinder filled with liquid nitrogen to within 6
inches of the top and never less than 6 inches from the bottom. I also
want to know when it is half full.
I have a computer with two parallel ports, a solenoid operated cryogenic
valve with an interface to operate from a parallel port, necessary
plumbing to connect to a 1000 gal dewer of liquid nitrogen.
What other parts to I need to fabricate something to measure the liquid
nitrogen in the cylinder.
krj

Parallax wrote:

When i bought my boat, it was 10 yrs old and even then the fuel
sending unit didn't work. Over the years, I have replaced it 4 times
and it has NEVER worked right. Those damned sending units are such
crappy technology...electrical/resistive/ mechanical/floating going to
a meter, and they really expect this to work for any length of time on
a boat? So....
Useless idea #3741 (I am really going to try this one)

Take two pieces of flexible tubing maybe 1/2" diameter filled with
hydraulic fluid connedcted to a T. The base of the T has a 1/4" clear
hose going up to where it is visible in the cockpit. The two pieces
of 1/2" hose support the fuel tank whose weight compresses the fluid
causing it to rise. As the tank empties, the level in the clear
tubing falls. So, it is really measuring weight. But, no
electricity, no moving parts (except the fluid) and absolute
simplicity. Now, the problem, most fuel tanks are fastened down
firmly so when this thing is installed, it must be able to move a tiny
amount up and down (maybe should use 1/8" clear tubing).

Kelton:

I have to keep x-ray detectors cooled with LN2 and I check the level
with a dipstick. basically, I took a piece of plastic and painted it
black and I dip it into the LN2 Dewar and pull it out almost
immediately. A very thin and whitish layer of frost forms up to the
top level of the LN2 because the plastic is a poor thermal conductor.

However, I assume you want an automated method. So: I use an
ultrasonic level guage on a plating tank that simply attaches to the
side of the tank, it closes a relay when the level falls below the
detector. You would use one on the top to tell when it is overfilled
and one on the bottom to show if it falls below the minimum 6" and one
in the middle. They werent tooooooooo expensive but I cannot remember
how much. They do require that you have access to the tank wall
immediately adjacent to the fluid and if this is a dewar, it could be
a problem.

So...You might try a thermocouple probe just above the max level
(Dunno if they will go down to LN2 temps). My x-ray detector dewars
have a low LN2 indicator that could be modified for max level too. I
dont know how it works because I simply use my dipstik method.

If you really want to get complicated, you might try ultrasonic
methods (time delay reflectometry) to detect both the top of the fluid
level. I have seen such devices and they werent too expensive.

Kelton Joyner wrote in message ...
Parallax,
You seem to like figuring out solutions. How about this one.
I have a stainless cylinder 8 inches in diameter, 3 feet high, closed at
the bottom and open on the top.
I want to keep the cylinder filled with liquid nitrogen to within 6
inches of the top and never less than 6 inches from the bottom. I also
want to know when it is half full.
I have a computer with two parallel ports, a solenoid operated cryogenic
valve with an interface to operate from a parallel port, necessary
plumbing to connect to a 1000 gal dewer of liquid nitrogen.
What other parts to I need to fabricate something to measure the liquid
nitrogen in the cylinder.
krj

Parallax wrote:

When i bought my boat, it was 10 yrs old and even then the fuel
sending unit didn't work. Over the years, I have replaced it 4 times
and it has NEVER worked right. Those damned sending units are such
crappy technology...electrical/resistive/ mechanical/floating going to
a meter, and they really expect this to work for any length of time on
a boat? So....
Useless idea #3741 (I am really going to try this one)

Take two pieces of flexible tubing maybe 1/2" diameter filled with
hydraulic fluid connedcted to a T. The base of the T has a 1/4" clear
hose going up to where it is visible in the cockpit. The two pieces
of 1/2" hose support the fuel tank whose weight compresses the fluid
causing it to rise. As the tank empties, the level in the clear
tubing falls. So, it is really measuring weight. But, no
electricity, no moving parts (except the fluid) and absolute
simplicity. Now, the problem, most fuel tanks are fastened down
firmly so when this thing is installed, it must be able to move a tiny
amount up and down (maybe should use 1/8" clear tubing).

Dont know why i didnt think of optics immediately. The surface of the
LN2 in a dewar when its in temp equilibrium is a nice liquid surface.
Reflect a beam of laser light off it at a small angle. Figger out
where the refelcted beam hits for FUll, halfway, and nearly empty and
place your photodiodes appropriately.

Parallax wrote:

When i bought my boat, it was 10 yrs old and even then the fuel
sending unit didn't work. Over the years, I have replaced it 4 times
and it has NEVER worked right. Those damned sending units are such
crappy technology...electrical/resistive/ mechanical/floating going to
a meter, and they really expect this to work for any length of time on
a boat? So....
Useless idea #3741 (I am really going to try this one)

Take two pieces of flexible tubing maybe 1/2" diameter filled with
hydraulic fluid connedcted to a T. The base of the T has a 1/4" clear
hose going up to where it is visible in the cockpit. The two pieces
of 1/2" hose support the fuel tank whose weight compresses the fluid
causing it to rise. As the tank empties, the level in the clear
tubing falls. So, it is really measuring weight. But, no
electricity, no moving parts (except the fluid) and absolute
simplicity. Now, the problem, most fuel tanks are fastened down
firmly so when this thing is installed, it must be able to move a tiny
amount up and down (maybe should use 1/8" clear tubing).

Maybe could use 20 feet of heater hose flaked out under the tank,
and a weighted runout gague indicator on the condom on the other
end? A Thermostat could maintain the internal gas temperature,
and a barometric interpolation correction scale could be
permanently mounted beside the dial? A heel angle correction
would then be required, but with some throttle position sender
units and pendulums, all using regulated power from a battery
powered invertor could run a lap top with rs-232 inputs and
dc-serial digital interfaces to calculate the fuel efficiency
despite inaccurate fuel weight indications, even dithered from
clocked measurement cycle times calcutated from pitch, roll and
yaw pendulums, integrated with vertical accelleration indications
from the vector sum of the 5 sided system of pneumostatic
sensors, it should be about a five module machine code speed core
to enable useful measurements to be integrated with the gps
input. A seek and find shore concious routing algorithm would
enable automatic waypoint inputs and autopilot control to the
next most economical diesel or gas fuel vendor on the satellite
web, considering calculated true wind and current data. The
minute charges are more expensive than the stabilised satellite
tracker mortgage interest. Uplink data costs are ruinous!

I prefer a self tending club boom jib, and bungee on the tiller.
I don't need a dipstick, anymore.

A mercury switch sounds an alarm when it blows hard enough that
she tacks and wants reefing. In a hammock, who could tell?

Or, install and maintain an x-junkyard automotive float sender
like the one I scraped clean in my boat after 20 years of service
and now only requires that it match the cheapo replacement gague
installed by the last idiot owner to indicate properly? I know
what the inverted, shortened scale indications mean, so who
cares? I only spent 8 bucks on boat gas last season. Needed a tow
back on that, the one and only trip where I blew a head gasket
neccessitating an overnight stay at a dock near a Hell's Angels
midnight wedding in a graveyard. The gasket had been recently
replace by a mechanic (?) of a certain imperious culture. Good
thing too, as he left out a ball bearing in the oil pump too,
lost it into the main bearing gallery, but luckily it didn't fit
between the big balls. Fixed it with the head gasket. Stopped
that annoying ticking and raised the oil pressure. Got a tow
free, from a stranger, in New Brunswick on the Saint John River.
Sail the reversing falls! Enter Valhallah.

Bed and breakfast, cheap! Cottage, 3 bedroom, 1 bath, 500 feet of
private beach, solitary and private nudist mountain back yard,
classic f/g 29' TylerCraft sloop, dinghy, 500 bucks a week, meals
and (2 free) airport pickups included. Liquor, vehicle rental
extra. Private security service. Leave your phone number or email
addy here,

(
),

if you want a reservation. Prices rise, soon! Damage deposit
required. Only properly filled out forms will be scrutinised.
Moderation in many things, I sometimes suggest.

--
Terry K - My email address is MY PROPERTY, and is protected by
copyright legislation. Permission to reproduce it is
specifically denied for mass mailing and unrequested
solicitations. Reproduction or conveyance for any unauthorised
purpose is THEFT and PLAGIARISM. Abuse is Invasion of privacy
and harassment. Abusers may be prosecuted. -This notice footer
released to public domain. Spamspoof salad by spamchock -
SofDevCo

Kelton Joyner wrote:

Parallax,
You seem to like figuring out solutions. How about this one.
I have a stainless cylinder 8 inches in diameter, 3 feet high, closed at
the bottom and open on the top.
I want to keep the cylinder filled with liquid nitrogen to within 6
inches of the top and never less than 6 inches from the bottom. I also
want to know when it is half full.
I have a computer with two parallel ports, a solenoid operated cryogenic
valve with an interface to operate from a parallel port, necessary
plumbing to connect to a 1000 gal dewer of liquid nitrogen.
What other parts to I need to fabricate something to measure the liquid
nitrogen in the cylinder.
krj

A styrofoam float, 2 weights, 2 springy arm switches, string, a
battery, wire, a mount, fastenings.

Logic counts as a part? Check status bits on one port. Insulated
cylinder? Vent float? Ambients? How long do you expect 1000 gal
of N to last?

Whom are you freezing?

Terry K

Parallax wrote:

When i bought my boat, it was 10 yrs old and even then the fuel
sending unit didn't work. Over the years, I have replaced it 4 times
and it has NEVER worked right. Those damned sending units are such
crappy technology...electrical/resistive/ mechanical/floating going to
a meter, and they really expect this to work for any length of time on
a boat? So....
Useless idea #3741 (I am really going to try this one)

Take two pieces of flexible tubing maybe 1/2" diameter filled with
hydraulic fluid connedcted to a T. The base of the T has a 1/4" clear
hose going up to where it is visible in the cockpit. The two pieces
of 1/2" hose support the fuel tank whose weight compresses the fluid
causing it to rise. As the tank empties, the level in the clear
tubing falls. So, it is really measuring weight. But, no
electricity, no moving parts (except the fluid) and absolute
simplicity. Now, the problem, most fuel tanks are fastened down
firmly so when this thing is installed, it must be able to move a tiny
amount up and down (maybe should use 1/8" clear tubing).

--
Terry K - My email address is MY PROPERTY, and is protected by
copyright legislation. Permission to reproduce it is
specifically denied for mass mailing and unrequested
solicitations. Reproduction or conveyance for any unauthorised
purpose is THEFT and PLAGIARISM. Abuse is Invasion of privacy
and harassment. Abusers may be prosecuted. -This notice footer
released to public domain. Spamspoof salad by spamchock -
SofDevCo

Too complicated and too expensive. A three foot piece of phenolyic,
three carbon resistors spaces at 6" 18" and 30", some wire, and a DD25
connector to the computer. Remember rotary joysticks on computers to
play pong? Varying resistance gave different hex values to the program.
Carbon resistors submerged in LN2 have almost zero resistance. We now
have three different values for the computer. No expensive lasers,
urtrasonics, mechanical parts to freeze up and not move. High reliability.
My stupid idea #65891
Kelton

Parallax wrote:
Kelton Joyner wrote in message ...

Parallax,
You seem to like figuring out solutions. How about this one.
I have a stainless cylinder 8 inches in diameter, 3 feet high, closed at
the bottom and open on the top.
I want to keep the cylinder filled with liquid nitrogen to within 6
inches of the top and never less than 6 inches from the bottom. I also
want to know when it is half full.
I have a computer with two parallel ports, a solenoid operated cryogenic
valve with an interface to operate from a parallel port, necessary
plumbing to connect to a 1000 gal dewer of liquid nitrogen.
What other parts to I need to fabricate something to measure the liquid To
nitrogen in the cylinder.
krj

Parallax wrote:


When i bought my boat, it was 10 yrs old and even then the fuel
sending unit didn't work. Over the years, I have replaced it 4 times
and it has NEVER worked right. Those damned sending units are such
crappy technology...electrical/resistive/ mechanical/floating going to
a meter, and they really expect this to work for any length of time on
a boat? So....
Useless idea #3741 (I am really going to try this one)

Take two pieces of flexible tubing maybe 1/2" diameter filled with
hydraulic fluid connedcted to a T. The base of the T has a 1/4" clear
hose going up to where it is visible in the cockpit. The two pieces
of 1/2" hose support the fuel tank whose weight compresses the fluid
causing it to rise. As the tank empties, the level in the clear
tubing falls. So, it is really measuring weight. But, no
electricity, no moving parts (except the fluid) and absolute
simplicity. Now, the problem, most fuel tanks are fastened down
firmly so when this thing is installed, it must be able to move a tiny
amount up and down (maybe should use 1/8" clear tubing).


Kelton:

I have to keep x-ray detectors cooled with LN2 and I check the level
with a dipstick. basically, I took a piece of plastic and painted it
black and I dip it into the LN2 Dewar and pull it out almost
immediately. A very thin and whitish layer of frost forms up to the
top level of the LN2 because the plastic is a poor thermal conductor.

However, I assume you want an automated method. So: I use an
ultrasonic level guage on a plating tank that simply attaches to the
side of the tank, it closes a relay when the level falls below the
detector. You would use one on the top to tell when it is overfilled
and one on the bottom to show if it falls below the minimum 6" and one
in the middle. They werent tooooooooo expensive but I cannot remember
how much. They do require that you have access to the tank wall
immediately adjacent to the fluid and if this is a dewar, it could be
a problem.

So...You might try a thermocouple probe just above the max level
(Dunno if they will go down to LN2 temps). My x-ray detector dewars
have a low LN2 indicator that could be modified for max level too. I
dont know how it works because I simply use my dipstik method.

If you really want to get complicated, you might try ultrasonic
methods (time delay reflectometry) to detect both the top of the fluid
level. I have seen such devices and they werent too expensive.