Re: Column Height Of Material In A Hopper
Hello,
It seems you have a hopper upper portion of uniform cross section and certain height (say vertical portion) and attached to it is lower portion of hopper, which is converging to the outlet cross section.
There are specific formula and method to calculate material pressure at various levels. The material pressure is calculated in vertical direction and also perpendicular to the hopper wall. Firstly one calculates the vertical pressure at junction of vertical portion and converging portion. For this a formula is Janssen formula.
The aforesaid vertical pressure at junction becomes input for the pressure calculation in converging lower portion. The converging portion can be of 2 categories viz. steep hopper and less steep hopper. For this, there are formulae. Accordingly one finds the vertical pressure at outlet of the hopper. This pressure acts on the gate at the hopper outlet. If you want to convert this pressure into column height, then formula is as below:
Pressure N/sq. m = (Bulk density kg/cubic metre) x g x (H in metre).
Therefore, H column height in metre = (Pressure N/sq. m) / [(Bulk density kg/cubic m) x (9.81)]
Refer literature or standards such as DIN, to know about the subject. The pressure calculation in hopper, etc. is a big subject and it cannot be narrated here.
Ishwar G. Mulani
Author of Book : Engineering Science And Application Design For Belt Conveyors (new print November, 2012)
Author of Book : Belt Feeder Design And Hopper Bin Silo
Advisor / Consultant for Bulk Material Handling System & Issues.
Pune, India.
Tel.: 0091 (0)20 25871916
Email: conveyor.ishwar.mulani@gmail.com
Website: www.conveyor.ishwarmulani.com ■
Hopper Load On Gate
Below post maybe useful which include this attached files:
href="https://forum.bulk-online.com/showthread.php?4826-Weight-from-Storage-Hopper-on-Feeder&highlight=schenck" target="blank">https://forum.bulk-online.com/showth...hlight=schenck
Attachments
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Weight Of Material Acting On An Outlet.
A well designed hopper should not experience a high outlet load as most of the content weight is taken by the walls, so the overall height is irrelevant.
The weight acting on an outlet varies according to the hopper design and operating conditions. The minimum load is the unsupported mass of material under the arch of a critical opening size, which is approximately shaped as an inverted parabola with ends inclined at the reaction acting at the hopper wall, i.e the wall slope from the vertical plus the angle of wall friction. If the opening is wider that the critical span there is a superimposed additional load that is required to support the failing arch.
For a funnel flow hopper the inclination of the boundary reaction is the internal angle of friction of the bulk material and similar additional load is the critical orifice span is exceeded.
Account must then be taken of whether the hopper is designed for plane flow or radial flow, and whether there is likely to be impact loading during filling.
As the evaluation process is somewhat complicated, a crude rule of thumb may be used taking the max. weight acting on the outlet to be equivalent to a pyramid of height four times the maximum width opening for a plane flow hopper or three times the hydraulic diameter of radial flow hopper. ■
Column Height of Material in a Hopper
In a hopper or silo how to calculate the column height of material load which is acting on rack and pinion gate fixed below.(or)How to calculate the material load acting on the gate.
Let say,
AxB is the cross section of hopper at Transition zone
axb is the cross section of hopper at out let(above rack and pinion gate)
p is density of material
H is the height of hopper (transition zone)
please provide necessary information or method to find out the load.
thanks & regards
Raghu nathan ■