Re: Hopper Isolation Gate
It is good practice to provide a gate between a hopper/bunker/silo and the conveyor/feeder.
Sods Law says that the conveyor/feeder will fail when the hopper is full of material 
If you can use the gate as a flow regulating device is dependant of the stored material flow properties. I prefer never to rely on a gate for flow regulation. ■
Re: Hopper Isolation Gate
Yes i agree designer that the feeder will most likely fail when the hopper is full. However wouldn't most feeders failures be able to be repaired regardless of the hopper being full or not.
The only repair that i can think of is a belt replacement and that job should be a scheduled replacement thus empty hopper. The belt needs to unexpectedly fail to the extent where the feeder cannot run for one more hour to empty the hopper for the isolation gate to be useful. Is that scenario likely enough to warrant the expense of an isolation gate?
After talking to a gate supplier he mostly see the gates used where there is a bank of feeders and hoppers and emptying one hopper would also require emptying adjacent hoppers. I can see isolation gates being worthwhile in that scenario because the feeder maintenance/repair can be done while the adjacent feeders are working.
The situation i am looking at has a single feeder with a single hopper and I consider the isolation gate to be excessive. However I am happy to change my mind if I am missing possible failures and repairs or I am underestimating the likelihood of a catastrophic belt failure. ■
Re: Hopper Isolation Gate
To fit or not to fit, that is the question.
At the end of the day it's your call. ■
Re: Hopper Isolation Gate
Steel bars, liners which have come loose, lost maintenance tools and other such rogue belt slitting devices defy the laws of routine maintenance on belts. Don't believe it won't happen to you.
How big is the silo discharge opening? What is the gate cost? Are you looking at an expensive powered gate or a relatively cheap rod bar or hammer gate?
Calculate.... cost of gate/cost per hr to operate plant. That is how much time you have to fix the problem without a gate. ■
Hot Rods At My Age?
You seem to need a rod gate or the issue is not serious; methinks.
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Re: Hopper Isolation Gate
The opening is 2000 x 700. I was looking at either a hydraulic powered knife gate or a clam shell gate.
What are the cheap options?
Isolating the hopper with rods??? is that just allowing some 40mm holes in either side of the hopper so that some 1 inch iron bars can be hammered through to the other side to block the opening. What’s the spacing for those (bin has 1-8mm particles). Most of the study is about minimum opening to guarantee flow not max opening for non flow. What is done to prevent the holes on either side of the bin from creating a ledge for material to build up on? ■
Re: Hopper Isolation Gate
Rod gates are a cheap method of isolation as long as you don't have to use them too often.
The rod size and spacing depends on the flow properties of the stored material. Sometimes double staggered rows are necessary. According to the design, the rods may not need to be removed completely. ■
Isolation Gates For Hoppers
The knife gate or clamshell provides absolute safety
for the personnell working under the belt feeder, and prevents
spillage from entering the repair area under the gate.
lzaharis
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Re: Hopper Isolation Gate
Dear Mr. Peter,
You have the hopper of 100 tonne capacity for iron ore. It has opening size of 700 x 2000 mm. All equipment require repair and maintenance, so belt feeder can also require sudden repair and maintenance. As an example, belt has failed and to be revulcanised or to be replaced. Also, sometimes you will need to replace rollers below the feed opening etc. The failure of the rollers or idlers will not be so sudden and one can operate the belt feeder for emptying the hopper. However, if the belt has snapped, then there is no option to operate the belt feeder for emptying the hopper. So, usual / economical practice is to have the provision of rod gate at the outlet of hopper i.e. at the interface of hopper and belt feeder. The rods are to be removed and kept at a particular location and to be inserted when belt feeder is to be isolated from material in the hopper till the maintenance is done.
Please note that rod gate should not be used to control the feed into the belt feeder.
The rod gate construction is very simple, either you may make it or you may refer to the manufacturer. This is the least expensive option and very widely used in India.
Regards,
Ishwar G Mulani.
Author of Book : Engineering Science and Application Design for Belt Conveyors.
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: parimul@pn2.vsnl.net.in ■
Re: Hopper Isolation Gate
Originally Posted by I G Mulani
A rod gate is best designed so the rods are not completely removed (but are out of the material flow when retracted), completely removed rods are rarely to be found when you need them ■
Re: Hopper Isolation Gate
Dear all,
Is it not possible to blind the hopper ( The feeders receiving area - in this case 2000 x 700 ) by simple Mild Steel plates by means of bolts & nuts or stitch welding ( if there is no fire hazard with the material being handled ) ? I had tough experiences with rod gates.
Regards, ■
Re: Hopper Isolation Gate
Originally Posted by I G MulaniYou have the hopper of 100 tonne capacity for iron ore. It has opening size of 700 x 2000 mm. All equipment require repair and maintenance, so belt feeder can also require sudden repair and maintenance. As an example, belt has failed and to be revulcanised or to be replaced. Also, sometimes you will need to replace rollers below the feed opening etc. The failure of the rollers or idlers will not be so sudden and one can operate the belt feeder for emptying the hopper. However, if the belt has snapped, then there is no option to operate the belt feeder for emptying the hopper. So, usual / economical practice is to have the provision of rod gate at the outlet of hopper i.e. at the interface of hopper and belt feeder. The rods are to be removed and kept at a particular location and to be inserted when belt feeder is to be isolated from material in the hopper till the maintenance is done.
Please note that rod gate should not be used to control the feed into the belt feeder.
The rod gate construction is very simple, either you may make it or you may refer to the manufacturer. This is the least expensive option and very widely used in India.
Regards,
Ishwar G Mulani.
Author of Book : Engineering Science and Application Design for Belt Conveyors.
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: parimul@pn2.vsnl.net.in
Thanks very much Ishwar, i apreciate your sensible response...A rod gate makes sense to me considering the chances of it actually being required. A rod gate provides what i need considering the estimate i got from a supplier for an isolation knife gate was 175,000 AUD . I have sent you an email to purchase your book. ■
Hopper Isolation Gate
A two layer pin gate will solve your problem. I have used it for cement clinker, iron ore fines, solar salt and iron ore pellets. There are no leakages and you can control flow (not regulate) ■
Re: Hopper Isolation Gate
For completeness of the thread.
I will be using a rod gate that has 30mm dia bars at 50mm centers. The rods will be threaded so that i can get the rods out after putting them in. The Rods will have a 30 degree taper to make it easier to penetrate a full hopper.
The installation will be designed to not have any obstruction to flow when the bars are not installed. The bars will be inserted through vertical hopper walls rather than through sloping hopper walls. ■
Re: Hopper Isolation Gate
450GASGAS, You have reached a sensible conclusion.
How are you going to thread the rods so that it assists removal? Or is just the end threaded so that a pulling ring can be attached?
Vinayak, I like your idea, thank you for the suggestion. ■
Re: Hopper Isolation Gate
Originally Posted by J DHow are you going to thread the rods so that it assists removal? Or is just the end threaded so that a pulling ring can be attached?
Vinayak, I like your idea, thank you for the suggestion.
There will be a nut welded to the outside of the frames and a nut or bolt head on the end of the threaded rod. The rods basically become a very big bolt. The rod can be turned with a spanner on the bolt head and that will wind the rod into the hopper. ■
Re: Hopper Isolation Gate
Originally Posted by 450GASGASFor how long before the threads get corroded and bind up in the nuts and the gate no longer works 
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Isolation Gates
We supply a lot of rod gates to isolate feeders. The best selection is a manually powered hydraulic horizontal slide gate. They are inexpensive, easy to use, and very positive.
You can check www.picor.biz for information. ■
Hopper Isolation Gate
Are hopper isolation gates necessary above a belt feeder?
I have a single 100 tonne iron ore hopper above a single belt feeder and an issue has come up regarding isolation to work on the belt feeder. The isolation gate is not to stop uncontrolled discharge as the stationary feeder will do that job.
If the material is benign and the feeder can control the discharge I can see the isolation gate only being usefull if the feeder fails and repair is required underneath the hopper. Is the frequency of such a scenario such that an isolation gate is warrented when the the take up and and drive are not underneath the hopper?
The only situation I can think of is if the belt failed or tore very badly, that the feeder couldn't keep running to empty the bin then the isolation gate would be required. Is this situation that likely that an isolation gate is warranted? Or are ther other situations scenarios that make these isolation gates necessary?
Thanks
Peter ■