Maintenance cost for valve and seive trays are comparatively more than bubble cap tray due to their relatively complicated construction features
Bubble cap trays though most expensive are the best in situations, where low vapour rates is to be handled and a positive liquid seal is essential at all flow rates
Murphree efficiency of all the three trays are nearly equal, however the peak efficiency is generally higher for seive and valve trays than the bubble cap
Valve trays have the highest turn down ratio (i.e. the ratio of the highest to the lowest vapour flow rates) and thus provides the maximum flexible operating range
Tendency towards stable operation is increased by increasing the skirt clearance of the caps, lowering the rate of liquid flow per unit plate width or increasing the spacing between the caps
The pressure drop due to the caps & slots and the static submergence should be as high as practicable for reasonable operation
The dimensionless ratio of liquid gradient to pressure drop head caused by the bubble cap assembly should be less than 0.4
EXAMIANS