I was asked to solve the following problem on my test:

A tank is filled up to height H with a liquid having specific gravity 1.6. The rest of the tank is filled with air. A pressure gauge attached on top of the tank measures the pressure to be 11.5 m of water and another pressure gauge attached at the bottom of the tank reads 16.8 m of water. Now, what is the value of H?

I don't know where to start. I have solved U tube manometer problems but never faced something like this one. I don't have a single clue. Even the total height of the tank is also not given. Is it really possible to solve the problem with only single data (the SG of the liquid) ? What do you think?

  • 1
    $\begingroup$ Yes, the SG is the density relative to the density of water so the liquid has a density of 1600kg/m3. For the height use the difference in pressures and density... $\endgroup$
    – Solar Mike
    Oct 28, 2017 at 20:47

1 Answer 1


I'll only outline the steps : 1) SG to density : Sg of 1.6 gives density as 1600kg/m3

2) pressure difference is given from the two gauges 5.3m of WATER...

3) calculate the pressure created by 5.3m of water

4) re-calculate for Height as Pressure / (density * gravity) but this time use 1600...

Neat that you have to spot that the gauges are in metres of water....

I assumed gravity as 9.81 m/s2, and ignored gauge pressure as it's the difference...

  • $\begingroup$ So, what did you get as the answer? $\endgroup$
    – Solar Mike
    Oct 29, 2017 at 15:34
  • $\begingroup$ I got 3.3125 metre $\endgroup$ Oct 29, 2017 at 16:23
  • $\begingroup$ So did I, should be good to go! Best of luck with the rest ! and accepting an answer with a tick if the answer is good is normal... $\endgroup$
    – Solar Mike
    Oct 29, 2017 at 16:43

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