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head pressure oil versus water in psi

head pressure oil versus water in psi

head pressure oil versus water in psi

(OP)
Hello, I'm in need of a head pressure factor for 1' of water versus 1' of oil (say, 30 weight viscosity) . I have found a factor of .43 psi for 1' of water and oil is less dense than water so I know the figure should be less than .43 psi. Any help on this matter would be appreciated. I don't have a specific gravity on the oil either although I suspect it is around .90 (1.0 for water)Thanks, John

RE: head pressure oil versus water in psi

PSI/ft for water = 62.4 pcf/144 sq. in = 0.433

If s.g. is 0.9, the PSI/ft = 0.433 x 0.9 = 0.39

RE: head pressure oil versus water in psi

You can convert API gravity to Specific Gravity (relative to water) by

SG = 141.5 / (131.5+APIGravity)

so 30 degree API crude would be

SG = 141.5 / (131.5 + 30) = 0.876

Which makes the hydrostatic gradient:

Gradient = 0.43 * 0.876 = 0.377 psi/ft

Now what I don't know is if SAE 30 weight is similar to the API 30 degree crude (I typed the above before I realized that you had asked about 30 weight, not API grades and thought it might be useful to leave it).

David

RE: head pressure oil versus water in psi

Pressure in PSI = head in feet x sp gr / 2.31

using SG 0.912

1 x 0.912 / 2.31 = 0.398 psi
 

RE: head pressure oil versus water in psi


It all depends on the accuracy required. When speaking of density of liquids (ρ) it would be better to state the temperature. For oils these are:
ρ = ρrek(T-Tr)
where
ρr, kg/m3, is the density at the reference temperature Tr, [K]
k is an exponent of temperature-density dependence (typically = 0.001/K)

A grade 50 base oil could also have a density of 888.7 kg/m3 at 10oC, while that for water would be 999.2 kg/m3 resulting in a ratio of 0.8894.

The ratio at 60oC, would be 0.8787.

RE: head pressure oil versus water in psi

Vale. blush I knew somebody would say that.  I always give SG and APIº values to std temp, unless noted otherwise. (60ºF)

BigInchworm-born in the trenches.
http://virtualpipeline.spaces.msn.com

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