In an earlier blog, Sentry Air application specialist Marie Haverstock discussed how the space required for specific work tasks could influence the dimensions of a custom hood.
In this entry, Marie discusses air volume, which is also a task-specific requirement that influences the design of custom hoods.
She starts with a mention of face velocity, which is typically defined as the velocity of air measured at the face of a fume or exhaust hood.
Velocity and speed sound like they may mean the same thing, but there is a difference.
[You might like this interesting discussion of speed versus velocity.]
The definition of velocity includes direction: so a face velocity of 100 feet per minute includes direction away from the face, or opening, of the hood, where the operator typically is positioned.
Marie then notes that the types and number of filters [e.g., HEPA, carbon, pre-filters] and the size of the opening needed for the task play a role in determining the power of the air cleaner required for the application.
We use CFM, cubic feet per minute, to rate the air flow of our air cleaners. Our entire product line currently offers from 100 to 1300 CFM.
When an application requires multiple filters, Marie notes it will likely need an air cleaner with an air flow greater than a single-filter application.
When necessary, more than one air cleaner can be designed into a custom hood.
Generally, air cleaner units are placed on the top of the hood.
However, for custom hoods, Marie notes we offer several options for placement of the unit.
Take a look at our new, animated custom hood video.
And check out Marie’s earlier entry on custom hood dimensions.