Face Velocity for Door Grilles

[offshorehvac]

Hello Friends

Are there any guidelines in National Building code or ASHRAE regarding maximum Face Velocity or free air velocity for air transfer grilles on doors/undercuts

 

[NeoMeche]

200-300 FPM is what I use. I don't have a specific code to source though. That is the recommended value on my TRANE ductulator.

 

[offshorehvac]

Thanks Neoneals

I was using 250 FPM but I need some valid document to justify my sizing on a project where consultant forgot to specify door grilles

 

[cdxx139]

neoneals is correct. If you need justification, have the consultant provide it, or JFGI.

knowledge is power

 

[offshorehvac]

JFGI since morning, nothing coming up

 

[DRWeig]

Agree with all. It's for noise and draft (comfort) control. You get too far above the 200-300 FPM range and the whistling / chilly feet will start.

Never seen a code or standard on this issue.

Good on ya,

Goober Dave

 

[KiwiMace]

At higher velocities, the grille pressure drop will increase to the point where it would not work across any realistic door dp. This is a basic engineering fundamental rather than anything that needs codified.

 

[Drazen]

1m/s is considered as maximum - rule of thumb survived for years.

 

[marcoh]

There are limits on door pressure before you need door openers, especially for disabled access. Not sure what the code says where you are but here the the maximum pressure accross a door is 12Pa. But as rule of thumb I always select door grilles at 1m/s.

 

[MECHJAMIECTA]

I agree with what others have said. I typically specify my door grilles ~200 fpm.

I know the TRANE ductulator says 200-300 fpm for both grille and door undercut as a rule of thumb but I tend to think 300 is too high (especially for door undercuts).

250 is my upper limit if I am trying to meet constraints on a project.

 

[cry22]

Normally, door undercuts over 1/2" will not maintain their 1-hour rating (used for toilets doors adjacent to corridors that are usually 1-hour rated).
Door grilles are seldom used nowadays for two reasons
1. If at hallways, then, they are a code violation nowadays, as door grilles are not fire rated, there may some rated doors with grilles, but it is your case?
2. transfer of room air to another, i.e use of a room as a return plenum is a code violation.

The question is: where and why a re you using door grilles to begin with?

you should use transfer ducts at ceiling with transfer grilles for toilet make-up air for example. if the wall is rated, you will need a fire damper at the TD. this is the general way things are done in the US, not door grilles.

 

[MechEngNCPE]

Don't use door grilles.