Mass flow rate

Hi surya.subra,

You can't get there from here. In other words, you cannot calculate the flow rate given only the pipe diameter and the pressure.

Mike

Then what some other parameter need for calculate the flow rate

You can use two pressure readings.

ok thanks. could you give the formula

http://www.engineeringtoolbox.com/steam-pressure-drop-calculator-d_1093.html

The CR4-related sources are helpful....

Thankyou verymuch

dear friend if u know pressure reading at two points, after calculation pressure drop

u can find the mass flow rate easily with darcy equation

but there are so many parameter u have to know like temperature, density, pipe material roughness,kinemetic viscosity, reynold number etc

deltaP=fLV2/2dg

mass flow rate=pipe areaX velocity x density

delta P=Pressure drop in m of water

f= friction factor

L=pipe length m

V-Velocity m/sec

d-pipe dia m

g-m/sec2

Thank you very much Manis

I'm not sure about this, but I understand that the Darcy-Weisbach (and the earlier Hazen-Williams) equations work for liquids (incompressible) but not gases (compressible).

For flow in relief valve systems, ASHRAE 15-2007 uses an even more complex equation, based on air. How easily it would adapt to steam I don't know. The Industrial Refrigeration Consortium (Univ. of Wisconsin, Madison) has a downloadable pipe segment calculator for this problem.

Non-Compressible Flow:

• Darcy-Weisback formula For Non-Compressible Flow
• Hazen William's Formula for Water

Compressible Flow:

• Darcy-Weisback formula For Compressible Flow (liquid/gases)
• Also Babcock/Fritzsche formula for Steam Flow

Hazen Williams method is only valid for water flowing at ordinary temperatures between 40 to 75 ^oF,

the Darcy Weisbach method can be used for other liquids or gases. this is valid not for only liquid (non compressible) but also for single phase flow (non compressible or compressible ) .In compressible flow there is problem of density varying with pressure but we can divide pipe line into such segments in which density remain constant and may calculate the flow rate if pressure drop is known. Over all pressure drop may be calculated by adding pressure drop in individual segments. In case of gases segment length will be short comparison to liquid

Please go to these link for more clarification

http://www.roymech.co.uk/Related/Fluids/Fluids_Pipe.html

www.nigc-khrz.ir/Research/E_Book/M17.pdf

Vortex-shedding flowmeters are satisfactory on steam. Try Endress + Hauser (usual disclaimer).

For steam you can use a differential pressure method requiring an orifice plate, pressure and temperature sensors or you can use a sonic flow meter. Google both... you might find our web site but we do natural gas.

Dear Mr.suryasubra,

You have not given the Temp. of the Steam for which you want to calculate the Steam mass flow. The specific volume of the steam will increase when the temperature of the Steam increases. Refer the Steam Tables.

However it can be calculated as follows. The principle is Area x Velocity = Volume of Steam Flow and this Volume devided by Specific Volume/Kg. will be the actual steam flow. The Velocity for saturated steam is taken as 40 M/Sec. and for Super Heated Steam it is taken as 50 M/Sec.

You haven the pipe size of 4 Inch and 6 Inch which is equal to 100.16 MM and 152.4 MM. The Steam pressure is 20 bar. Referring to the Steam Table the saturated steam temp. is 214.5 Deg.C and the Specific Volume is 0.094902 M^3/Kg.

The area for 4 Inch pipe is ((4 x25.4)/1000)^2 (3.14/4) = 0.00810 M^2 and velocity is 40 M/Sec. for saturated steam. Hence the Steam Flow = A x Vel. Which is (0.00810) x 40 = 0.324 M^3/Sec. This value should be devided by Sp. Vol, which is 0.094902 M^3/Kg.

Therefore the Flow is (0.324)/(0.094902) = 3.414 Kgs./Sec.and hence for one hour it will be 3.414 x 3600 = 12,290 Kgs/Hr or 12.290 Tonnes/Hr.

In the same way you can calculate the flow for 6 Inches for which the area to be calculated in Sq.M and same way you have to calculate, which will be 0.01822M^2 and the flow will be 27.64 Tonnes/Hr.

As I mentioned above, If the steam is superheated, the Sp. Volume will increase and the flow in Tonnes/Hr. will decrease.

DHAYANANDHAN.S