LPG Gas Cylinder

The simplest way is a set of scales to weigh them, with a clock, a pencil and some graph paper handy - that's what I'd use, then I'm funny that way. Maybe you could compare notes with akshaya?

Sir i am in need of mathematical formulas to calculate all my above parameters.

Madam, you can write your own from the lines on your graph paper.

What is it with the youth of today? Ye gods.

You appear to be lost in this task. And if you are a BE student, you better be able to create your own formulas to calculate simple things.

Your missing the point of this task, it's to design a system to measure the fuel remaining. This most likely requires the use of flow measuring devices, and integrate this over time to produce fuel left display. You certainly could put the tank on a scale, and subtract the tare weight, and then convert weight to mass of remaining LPG. You indicate it's a 2 burner stove of some sort. Do these burners have variable control valves, or are they ON-OFF? And is there a regulator that controls the low pressure gas to the burners? If not flow rate will be a function of temperature of the tank. And as the LPG is boiling off, it cools the remaining product, and as this is a saturated liquid gas, the pressure is a function of temperature. You can use the LPG at a rate where the tank frosts. And the pressure will continue to drop if the flow is this fast. Note the volume of the liquid in the tank is a function of temperature.

Sir,this project is implemented in home so the burners have variable control valves and low pressure to the burner is controlled by regulators.

So what? You're missing the point, Madam. You asked for suggestions. What you're invoking now is called "mission creep", and no-one here is going to do your work for you.

Let me know how you get on with your scales, clock, pencil and graph paper.

Get yourself one of these then:

Figure out how to convert the meter reading from NG to PG. It's a mechanical volume integrator, and temperature compensated.

It's clear, whomever has paid for your BE degree has lost this investment. You don't have the pattern recognition talent to be an engineer.

I understand to help some body who is not in school and has problems but to give to a STUDENT in a FINAL YEAR B.E. who is in school has a full team of professors who has access to all books he wants and to a lot of informations to build up his equations and make his project I shall NOT do because the goal of school is to give the students the possibility to work by themselves. I helped several in the past years but because they already did their work and were in troubles with aspects a student cannot master.

It is not the case for the present OP. He did not make the smallest step in searching what he should do he wants to get a degree without any effort.

This I do NOT support.