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Bezzera

Author Topic: back pressure from butterfly valve  (Read 3929 times)

Summercrema

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back pressure from butterfly valve
« on: 13/07/2015, 08:47 PM »
I have an early model 2kg HG(2007 High pressure model)  and it has a brass control gas valve, it has been giving me many good results for years it is just that I hope there is something I can do to better control the back pressure (btw 20 kpa -30  kpa) when I lower the gas during development stage , I don"t know whats out there and is there a back pressure control valve for it, buying a new roaster is not on the shopping list either. Just hope someone can point me to the right direction. Thanks.



Brett H

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back pressure from butterfly valve
« Reply #1 on: 13/07/2015, 08:51 PM »
Hi mate... Do you have a Gas Fitter locally? I'd be starting there as the potential for danger is as near as your computer keyboard.  Please however report back with your findings... It's an interesting question and scenario.
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back pressure from butterfly valve
« Reply #2 on: 14/07/2015, 11:31 AM »
Yeah ditto I'd be going safety first and also speaking to the local importer
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askthe coffeeguy

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back pressure from butterfly valve
« Reply #3 on: 14/07/2015, 11:34 AM »
Talk Coffee and or Coffee Roasters Australia should be able to help you out as they're both approved agents but again I'd be going to a gas fitter as safety precaution and first port of call - might save you quite a bit of money as well ...
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back pressure from butterfly valve
« Reply #4 on: 14/07/2015, 01:56 PM »
Without knowing anything about the actual set up, hard to advise.

However I cant see why there would be a problem. When you shut down the roaster, you turn off the gas? Yes?  (well I do).

Then it is the same story when you roast./...you turn the gas down or off? What is the diff?  :)

We don't know what control valve and regulator assembly you have fitted so, yeah, if for your own piece of mind you want to investigate this further, I would be calling your gas train supplier/service agent.

*******************

And I have just asked the boys to get me a photo of what lives behind the 5 kg Toper for comparison. Back shortly.

Ok so only as an example, all of this lives behind the 5kg Toper, which runs on natural gas at a lower pressure than LPG. Then below all that, at the entry to the machine burners, there is a fancy variable control tap that is used to deliver more or less gas during roasting. All that stuff was bought here (ie not factory supplied with the machine....or should I say, what was supplied with the machine was binned and replaced with this). 

You need to refer to your gas people, and I wouldn't imagine there would be much diff if any between a 5 kg and a 2 kg commercial roaster in respect of the gas train.

All that you can see in the photo, was fitted BEFORE we were issued a Compliance Certificate (or whatever it is called depending on which state you are in) for the gas train.
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Summercrema

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back pressure from butterfly valve
« Reply #5 on: 20/08/2015, 10:40 AM »
just an update on pressure valve issue, actually there is a second gas regulator equipped from day one that I just realized I can use to control the flow of gas, it is very precise I am happy with it.

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back pressure from butterfly valve
« Reply #6 on: 20/08/2015, 01:51 PM »
If you are in Australia, then it's likely from your photo that your installation is not Energy Safe compliant.
It's been said before many times, this is critical for any Type B appliance such as coffee roasters.
Insurance companies love looking for loopholes to avoid payouts when loss adjusting.
If you have any type of fire, even a minor incident and you submit a claim, expect a visit from an experienced fire investigator.
The first thing they will do is ping you for your flexible gas lead I can barely make out in your picture. All connections need to be fixed piping.
Further to that, you need Energy Safe compliance for 2 separate areas - the supply connections need to be ES compliant and so does the appliance.

In relation to your regulator - these work on a simple principle - known input pressure range and known output pressure range. The regulator needs to be designed for your required pressure ratings on the input and output side.

It appears from FC's post above that there are multiple regulators involved with the Toper in order to achieve the desired pressure that allows the burner to work correctly. This is quite common where a high pressure feed is to be converted to low pressure.
Most regulators work with a spring tension. The spring controls a valve and for some regulators it's possible to source just the spring you need for the required pressure and fit that spring to your regulator.
Multi-block regulators are more sophisticated and use electronic solenoids and damping controls to automatically range the pressure. These are most often found with package burners that have ratio mixers for air and gas. Multi-blocks are not fool proof and you can experience silly things like springs or dampers sticking.
Some regulators also have filters which may start to clog over time.

What you are dealing with here is something that only an approved and qualified gas fitter should be undertaking. A roaster is not a BBQ.


Bezzera

 

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