Measuring Liquid Nitrogen

AnnetteM

Hello

I need some help with measuring Liquid Nitrogen. We have 1500 gallon tank. When the nitrogen is delivered, the qty is measured in SCF. There is a gauge on the tank is reading in %. I thought this meant % of gallons. However, I've learned the % is Ins WC. How do you convert Ins WC to SCF?

I want to verify the qty I'm being billed. I believe our company has been over charged.
As an example if the gauge was reading 41.80% Ins WC and was then filled to 97.90% WC, how many SCF should I have received?

Thank you for your help!

Annette

jumper

Shape of tank?

EBEBRATT-Ed

I am thinking that the Nitrogen in the tank is saturated that is the tank always contains both liquid nitrogen and nitrogen gas.

It's just like a tank of refrigerant. I don't think you can know what's in the tank unless you can weigh the tank which may not be practical.

Gage reading will probably be no better than an approximation

AnnetteM

The shape of the tank is an upright cylinder approx 15ft tall.
The tank can hold 1500 gallons. I'm familiar with converting gallons to SCF, but not WC to SCF. thanks

HVACNUT

Well. I just Googled SCF (supercritical fluid). It is any substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist.
I'm no chemist, but to me SCF is not a measurement of weight, mass, volume or quantity. It's merely a factor of density of a particular substances temperature and pressure. Obviously W.C. is a measurement of pressure, but I don't know how a gauge can convert X pressure and Y temperature into SCF. Therefore, I think using SCF as a quantity for billing doesn't seem correct. Although I could be completely out of my depth on this topic.

HVACNUT

I think you need to contact Will Hunting.

JUGHNE

This "SCF" is not Standard Cubic Feet??

How about a picture of that gauge on the tank?
Just curious, what are you freezing?

HVACNUT

> @JUGHNE said:
> This "SCF" is not Standard Cubic Feet??
>
>
>>See, I knew I was out my depth.
It sounded smart though, right?

Canucker

How full is your tank when it's full? Is 1500 gallons the size of the tank or is that the maximum fill? I would be surprised if your WC reading wasn't the %full the tank is.

JUGHNE

Dude, yea I was really impressed....I really started to feel out of my own depth.....actually I still am.
Would the % of fill gauge simply show the liquid in the lower part of the tank, like LPG.
But in the LP case the truck has a gallons meter to bill you with.

That is why seeing the gauge is needed IMO.
The ID plate that is usually welded to a tank of this sorts would give some clues to actual capacity.

JUGHNE

Another thought.....have seen WC meaning "water capacity" IIRC.

ChrisJ

I think it's clear no one on this forum knows what the standard practice is when measuring a tank full of liquid nitrogen.




Though I suspect @EBEBRATT-Ed was right, there's no real way to tell how full a tank is from a pressure gauge. You either need a scale or a float, similar to a LPG tank. Pressure is going to change with ambient conditions and not so much with the level as long as there's some liquid in the tank.

Either way, if you're trying to dispute a delivery, you need someone that knows without a doubt how this is done, and I don't see you getting that here.

Canucker

> @ChrisJ said:
> I think it's clear no one on this forum knows what the standard practice is when measuring a tank full of liquid nitrogen.
>
>
>
>
> Though I suspect @EBEBRATT-Ed was right, there's no real way to tell how full a tank is from a pressure gauge. You either need a scale or a float, similar to a LPG tank. Pressure is going to change with ambient conditions and not so much with the level as long as there's some liquid in the tank.
>
> Either way, if you're trying to dispute a delivery, you need someone that knows without a doubt how this is done, and I don't see you getting that here.

Let's wait until my question gets answered before we decide nobody knows how to measure a tank

Wardo

I suspect its a differential pressure gage reading percent of full capacity.

Why don't you ask your supplier to provide a full explanation?

BobC

I assume this tank is a gas pak of some sort, they slowly outgas nitrogen between the inside and outside tank (think bottle in a bottle) to keep the inside tank very cold and at low pressure.

I used to deal with gas paks that were aboutb6 ft high and 30" in diameter, we paid by the amount of liquid nitrogen (in pounds) when it was delivered. If you left that tank on the loading dock over a hot weekend (in the sun) the tank would be 30% less full come Monday morning, Note that all of this info is about 25 years old but thats the way things were in the early 90's.

Does the user own this tank or is it the property of the supplier of the nitrogen.

Bob

ChrisJ

BobC said:

I assume this tank is a gas pak of some sort, they slowly outgas nitrogen between the inside and outside tank (think bottle in a bottle) to keep the inside tank very cold and at low pressure.

I used to deal with gas paks that were aboutb6 ft high and 30" in diameter, we paid by the amount of liquid nitrogen (in pounds) when it was delivered. If you left that tank on the loading dock over a hot weekend (in the sun) the tank would be 30% less full come Monday morning, Note that all of this info is about 25 years old but thats the way things were in the early 90's.

Does the user own this tank or is it the property of the supplier of the nitrogen.

Bob

Gas pak?
https://en.wikipedia.org/wiki/Gas-pak


I think you meant vacuum flask or "Cryogenic storage dewar" ?
https://en.wikipedia.org/wiki/Cryogenic_storage_dewar


The 1500 gallon tanks I see, appear to be high pressure tanks.

Gordy

Canucker said:

> @ChrisJ said:

> I think it's clear no one on this forum knows what the standard practice is when measuring a tank full of liquid nitrogen.

>

>

>

>

> Though I suspect @EBEBRATT-Ed was right, there's no real way to tell how full a tank is from a pressure gauge. You either need a scale or a float, similar to a LPG tank. Pressure is going to change with ambient conditions and not so much with the level as long as there's some liquid in the tank.

>

> Either way, if you're trying to dispute a delivery, you need someone that knows without a doubt how this is done, and I don't see you getting that here.



Let's wait until my questiongets answered before we decide nobody knows how to measure a tank

That's because @chrisj can't answer it, so he assumes no one else can.

http://www.airproducts.com/~/media/files/pdf/company/safetygram-7.pdf

http://www.uigi.com/n2_conv.html

ChrisJ

Negative.

Gordy

The links have pertinent information. The right questions have been asked, and need answered.

ChrisJ

Gordy said:

The links have pertinent information. The right questions have been asked, and need answered.

My mistake dear friend.

Please help the OP out with some answers.

HVACNUT

I still like my comment the best. If I was a Bostonian, I'd be "Wicked smaat".

Wardo

Pleass see the last diagram at the bottom:

http://www.orangeresearch.com/why-differential-pressure-gauges.php

Annette is probably long gone by now.

BobC

@ChrisJ The supplier we bought the nitrogen referred to it as a gas pak, as I said that was 25 years ago. This is an image of the tanks I worked with, your right about it being a cryogenic tank of some sort. If you store liquid nitrogen at room temperature in a single wall tank i will be at well over 1000 PSIG, it would take a very heavily built tank to store 1500 gallons of it. I remember the empty 50# CO@ tanks weighing over 150 # for the tank alone.

Bob

ChrisJ

BobC said:

@ChrisJ The supplier we bought the nitrogen referred to it as a gas pak, as I said that was 25 years ago. This is an image of the tanks I worked with, your right about it being a cryogenic tank of some sort. If you store liquid nitrogen at room temperature in a single wall tank i will be at well over 1000 PSIG, it would take a very heavily built tank to store 1500 gallons of it. I remember the empty 50# CO@ tanks weighing over 150 # for the tank alone.

Bob

My dry Nitrogen tank is heavy and that's only 60 cubic feet @ 2200 PSI.

I can't imagine a 1500 gallon version but I suppose it's possible.

Gordy

Heavy and expensive. I'm picturing this as the op's tank. Used 22500.00. 1500 gal. 250 psi.
https://www.diecastmachinery.com/id_4150_Chart+Industries+Inc_1500_Gallon_Cryogenic+Bulk+Storage+Tanks?gclid=EAIaIQobChMI6fH1-O6s1QIVRhuBCh33QgyhEAAYAiAAEgJWBvD_BwE

bob_46

I worked at a facility where we piped 1000PSI all over a 150 acre site. Semi tankers every day to keep up with demand so they installed a gadget about the size of a giant farm silo to make N2 gas on site. Maximum flow 70,000 SCFH . Liquid storage 15,840 GAL. or 1,475 000 SCF. Also piped a coaxial liquid N2 system , 1/2" inside 1" if I remember with a deep vacuum maintained in the annular space. Inside -325ºF outside room temp amazing .