7 replies to this topic

[Mohit Kumar]

please explain to me which direction hole should be punched in sieve tray. Top or Bottom?

 

Is it true that bottom punched holes gives less pressure drop as compared to Top punched holes.If yes,please elaborate the possible reasons.

[fallah]

 

Is it true that bottom punched holes gives less pressure drop as compared to Top punched holes.If yes,please elaborate the possible reasons.

 

Muhit Kumar,

 

It can be true because bottom punch hole will generate less entrance pressure drop against vapor passing movement through the hole...
 

[Mohit Kumar]

wow..thanks for quick reply.

 

Is this also true with Valve tray.?

 

Can you tell me how significant will be the difference in Pressure drop because of hole punched direction

[fallah]

 

Is this also true with Valve tray.?

 

Can you tell me how significant will be the difference in Pressure drop because of hole punched direction

 

Muhit Kumar,

 

I think it cannot be applicable for valve tray....

 

Difference in pressure drop isn't so significant due to hole punch direction in sieve tray...
 

[Mohit Kumar]

Fallah Sir,

 

For valve trays, Bottom orifice means flat orifice and top orifice means extruded orifice.

 

can it be the reason for different pressure drop as applicable in sieve trays?

[fallah]

 

For valve trays, Bottom orifice means flat orifice and top orifice means extruded orifice.

 

can it be the reason for different pressure drop as applicable in sieve trays?

 

Muhit Kumar,

 

It might be considered as an apparent reason, but in real world a valve tray isn't installed at the tray bottom hence cannot be an option for valve tray installation....
 

[PingPong]

please explain to me which direction hole should be punched in sieve tray. Top or Bottom?

The reason that in sieve trays the holes are usually punched downwards is to avoid injury for personnel working inside the tower during installation, inspection or maintenance, since the punch exit is usually sharp or rough.

 

Disadvantage of punching downward, with the punch exit against the direction of the vapor flow, is increased pressure drop, so in situations where low tray pressure drop is essential the punch direction for sieve trays is usually specified by the design engineer to be upward.

Edited by PingPong, 17 June 2016 - 08:29 AM.

[Bobby Strain]

I leave tray details to the supplier (for 50 years). So your specification should include allowable pressure drop.

 

Bobby