I believe the screen is meant to keep stuff out of the vent, BUT it could actually be the opposite and the screen is supposed to be keeping stuff in. I would do the test both ways with various size of material and screen size.
The biggest word has only 6 letters and every word is in very common use even by people with minimal vocabulary. I don't know how it could be explained in a more simple or clearer manner. Is this a wind up of some sort.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
The reason the Swedgelock device is called a "mud dauber" is that flying insects have been known to build nests on the end of vent pipes to take advantage of the heat of the vented gas. The screens are to keep the nests from actually plugging the pipe which can disable a continious bleed level controller (the damn bugs still build the nests on the warm pipe, but the screen can blow out if it gets plugged).
Is this the setup line for a joke? If so, then I think it means the same as "Check them, to see if you rectum", an anatomical reference to incontinence. I believe the traditional testing procedure involves the pulling of one's little finger.
To seriously answer your question: screens come in different mesh sizes -- from coarse to very fine. A coarse screen might have openings as large as 1", while a very fine mesh could be as small as 1/32" inch. "Fine" mesh is somewhere in between -- I would classify it myself as a screen with openings under 1/4".
A trip to a local hardware store and talking to a salesman there will probably give you a real good idea of the different grades.
In your case you don't want a very fine mesh, as this would tend to trap dust and dirt and decrease the efficiency of your vent. But you want to make sure that the screen mesh size is small enough to keep out most bugs and large particles.
Patricia Lougheed
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.
McMaster-Carr defines fine mesh as 61 x 61 mesh up to 1500 x 1500 mesh. The numbers are openings per linear inch in each direction. By this definition, Patricia's 1/4" openings would be in the "coarse" category. In fact, the 1/32" mesh wouldn't even qualify as "fine"!
As others have already said, the particulate size needs correctly specifying by the customer or the unit's OEM. Otherwise, (and taking previous precedent for a corny pun), it'll be very nearly like the Laurel and Hardy punchline - "That's another fine mesh you've gotten us into!"