Bronkhorst Vapor Delivery Module - Manual (Page 20)

Bronkhorst®
Vapor Delivery Module 9.17.079 20
5.3.1 Operation example
Application
The Vapor Delivery Module can be used for generating certain humidity in a gas stream. Carrier gas and liquid (water) are
controlled to regulate the humidity. The water is mixed with the gas and consequently evaporated. The humidity at a certain
temperature corresponds with a certain ratio of gas and water, this ratio can be set by the flow controllers which are part of the
Vapor Delivery module.
Calculation example for setting of relative humidity
At atmospheric pressure, at 80°C, 2 l
n
/min Air has to be moistened. Which water flow is needed for a r.h. of 50%. The vapor
pressure of water at 80°C is 473.3 mbar according to FLUIDAT®.
i
www
FLUIDAT® on the Net: Bronkhorst High-Tech's interactive Flow Calculations and routines generating Physical
Properties. Visit www.fluidat.com
Assumptions: Consider water vapor as an ideal gas, 1 mole of ideal gas at normal
conditions = 22.4 l, 1 mole of water is 18 g and 1 hour is 60 min.
1 atm. = 1013.25 mbar.
At 100% r.h., the (Mole)Ratio between gas and water is:
The MoleRatio:
So in a gas flow of 2 l
n
/min, the saturated vapor flow (100% r.h.) is:
[l
n
/min]
and in [g/h]:
[g/h]
At 50% r.h., the (Mole)Ratio between gas and water:
The MoleRatio:
so in a gas flow of 2 l
n
/min, the saturated vapor flow (50% r.h.) is:
and in [g/h]
[g/h]
Result: at 50% r.h., the water flow is 29.41 g/h.