What affects the flow properties of a gas ?

[carla00]

Hi,

A quick question, I'm looking at two fire suppressant gasses, HFC 125 and HFC 227ea. One of which flows much better than the other. I was wondering which is the main property that affects the flow of the gas ? I was thinking vapour pressure but am probably wrong ! if you want to look into it, the Kidde website gives the properties

http://www.kiddeaerospace.com/table_1.shtml.

there is a large difference in the flow properties of the gasses so was wondering why ?

Any ideas ?

 

[btrueblood]

Do you mean one flows more? IIRC, "halon" fire suppressants are stored and delivered as liquids. One of the two fluids has a higher density, thus a larger mass flow rate of the liquid through a given orifice would be expected.

 

[carla00]

Hi, I mean when they are flowing through pipework as a gas. One of them has to be overpressurized with nitrogen to help it flow whereas the other flows easily through pipework.

 

[25362]

The reasons for "superpressurizing" bottles of HFC-227ea with nitrogen are :

[•] To facilitate gas flow as carla00 explained (its latent heat of vaporization is ~ 57 Btu/lb, cooling the liquid and reducing its vapor pressure)

[•] To provide a pad to enable the liquid to be transferred without flashing

[•] To maintain sufficiently high pressures at low ambient temperatures