General Level Measurement Calculation

you need to just decide what will be ur low level of tank suppose you have desided 50 litters

and a high level is 1000 liters

feel tank manually of 1000 L water by manually weighted or calculated

insert your level sensor inside it [\p]

I thought it will.be a capacitance type 4-20 mA output level sensor

after filling 50 L of water u can set level sensor zero (4 mA)

then fill tank with fully.1000 L water and set span of level sensor (20 mA)

no marking is required a level sensor will than autonatically detect a water level

I have given a example for 1000 L tank you can do.for any

if a tank is of very large capacity you can ask to vendor for supply a tank with.inbuilt level sensor. which is precalibrated for exact level measurement

or if a vendor ha supplied a tank with pre-marked level in tank you can do a level sensor zero and span settting by adding any liquid which is senseble by aclevel sensor as mentioned above by me

I intend to make a spreedsheet that would manually calculate the level with known dimension of tanks. I have decided my low liquid level to be 10% of any given tank. I need to relate the measurement span to a 4-20ma output signal ( not specific to a particular instrument) so as to determine the liquid level from the output signal reading manually.

here you have mentioned " How do I relate the Measurement range of instrument and the tank dimension with the output signal of 4-20ma"

can you please explain what kind of instrument do you want to use for level meaaurement

ultrasonic , fiber optic , capcitance contact type....

and where u r using this output 4-20 mA

if you are a programmer than it is no need to tell how to convert measurement range into 4-20 mA out put

Ordinarily, the 4-20mA represents 0-100% level signal. There are ultrasonic and other instruments that have a linearising function set on-board as part of their programming. Thus 4-20mA can be 0-100% volume instead, which is particularly interesting for tanks that do not have a constant cross-section.

If the selected instrument does not have this function, then the calculations need to be done within the device that has the input for this 4-20mA signal.

It is difficult to say more in the absence of the make and model number of the chosen instrument and the type of equipment to which it is connected.

for that lots of calculations you need to do

»also you need to consider what type of tank u r using reqtangle , spherical with flat base , spherical with half spherical base

tank length, up to what size liquid to be filled , tank width

will take lots of time...

will come back to you

www.regaltanks.co.uk/calculator/

Thanks alot for taking your time to analyse my post step by step. I am just concern about the level of the liquid. I am considering a vertical cylinder, horizontal cylinder, vertical and horizontal bullet. I am also considering using the volume calculation of the liquid content i.e Volume=area x height . I want to take the height as the level and also consider a 4-20ma output signal proportional to 0-100% to calculate the correct liquid level at any given output signal say 7ma, 12ma etc.

If only level is wanted, then only linear scaling is needed. Most PLCs for example, have an input scaling function as part of their standard programming set, which is ideal for this task; it comes out in one line of code.

Still no clues about the specific instrument. If the instrument were one of several types in the Vega range (usual disclaimer) for example, then a linearising function set will probably be found within the instrument itself. The instrument output then becomes 0-100% volume, which can then be scaled into actual volume stored if needed using a scaling function.

• Vertical cylinders are commonplace, and no linearising function is needed. A horizontal cylinder will need one as its cross-section varies with depth.

Contact the instrument manufacturers directly to discuss needs and facilities/features.

Level (not volume) % of sensed range = 100(mA-4)/16.

With that kind of laundry list, you need to consult with a level guy (distributor/rep) in your area.

If possible, look for someone who sells more than one technology, otherwise the single technology miraculously does it all. That might be the case, but it might not be the best fit.

The technology choices are continuous DP, submersible DP, radar, guided wave radar, ultrasonic, bypass sight, magnetostrictive, capacitive, bubblers (DP), laser, and nuclear. The goal is to pick the best fit for what you're trying to accomplish, not to be sold someone's sole offering.

Here's a partial list of the multitude of considerations that make it difficult to assess remotely
- how the tanks are to be used (day use, storage, variety of product)
- purpose of continuous level (indication vs control, inventory, point level limit needed)
- mounting location (top, bottom, threaded, flange)
- media characteristics (foam, crud, sticky, dielectric, vapor pressure, temperature)
- tank functions (fill, drain, agitation, atmosphere blanketing, venting, pressurization, heating/cooling jackets, internal structures)
- industry considersations (approvals, sanitary, general or hazardous area)
- accuracy expectations
- volume conversion capabilities
- fault considerations
- local or remote indication
- signal - analog, HART, other digital, wireless, alarm relays