Food dryer project

[Spoon]

Fact is he has pressed ahead with this project with massive determination and already overcome many technical & practical obstacles to get to where he is, and I admire that greatly

Getting something to work is a lot easier than getting it to work properly. We can all get a £1 relay and use it on a stop circuit, therefore saving loads of money......
Anyhow I feel I have bleated on long enough and repeated my concerns enough now...
Hopefully its all been designed correctly and things will go swimmingly..

 

[grumpyjohn01]

Excalibur COM2 Stainless Steel Two Zone Commercial Dehydrator - 4800W - https://www.webstaurantstore.com/excalibur-com2-stainless-steel-two-zone-commercial-dehydrator-4800w/358COM2.html
looks like some has beaten him to it .

yeah, he has 2 of those already...how can I put it...they don't really work... well not consistently, for his application at least...hence embarking on this project

 

[grumpyjohn01]

Getting something to work is a lot easier than getting it to work properly. We can all get a £1 relay and use it on a stop circuit, therefore saving loads of money......
Anyhow I feel I have bleated on long enough and repeated my concerns enough now...
Hopefully its all been designed correctly and things will go swimmingly..

Thanks for your time on this, believe me , all your concerns have already been voiced and the client does appreciate them, we are just looking to navigate a path..

 

[grumpyjohn01]

Thanks again for all replies, I think I knew the types of response I would get, so no great surprises...Still, if there is anybody out there who thinks they could assist with some genuine informed practical advice. Please PM me, it would, I'm sure, be rewarded and appreciated.

 

[Darkwood]

This little project would be right up my street but unfortunately Dorset is out of my local reach, I see a few questionable design issues already that would impact the ability for a even temp' across the unit, I was involved many years ago with the an oven design that had to maintain a equal temp' throughout it was a critical application used in the aviation industry and temperature control had to be even and precise to the degree.
That aside you also need to realise this will not come under the BS7671 and will fall into the machinery standards, there are strict regulations and will affect everything from design, control and system safety, there are no short cuts, you cannot make a functional unit without adhering to the standards, if this was a garage project to test the concept then yes but if this is indeed going to be trialled and used by staff, employees or other third parties then it will have to meet all standards and be certified, also it may have to comply to food safety standards too, this may be covered if this falls within a specific area of the machinery control standards.

I understand the temptation to get involved but I would keep well away as your involvement would put the responsibility of the control system on you shoulders regardless of any promises made, I take it you will not be covered on your insurance for this and it could void your existing cover if you are found to be working on equipment/systems that you have not declared to you insurer.

I would suggest he seeks a local machinery control designer who will be able to provide all the design, cert's, wiring schematics etc as required for such a system.

 

[elsparko]

Hi All, With some trepidation I am throwing this one out for comments / advice from members.
I have been asked by a customer to provide 3 phase supplies for some 'machines' that are under development by my customer.
The machines are basically cabinets for dehydrating food items , that have been designed by my customer as he has been unable to find a suitable commercial product that will meet his needs.
So far he has arrived at a test machine that has a fabricated upright steel cabinet with heating elements mounted at the rear and multiple fans at the front, drawing warm air over the food which is spread over trays stacked on a shelved trolley that is wheeled into the cabinet.
There are 3 x 3kW single phase heaters that are separately controlled by solid state relays and the fans are ELV units that are electronically controlled by a series of thermostatic probes, the idea being to maintain the correct temperature, humidity etc over the height of the unit so that the food dries evenly.
At present he has everything supplied via multiple 13A plugs connected to various sockets which may or may not be on the same circuit / phase. I have cautioned him on overloading circuits etc.
His prototype is now working (pic) and he wants to turn this into a finished appliance that will be used commercially and copied for use in his own premises.
Whilst he is taking full resposibility for the appliances themselves (compliance with relevant regs etc) I have been asked to install supplies and assist with packaging the electrical elements of the design.
I can see no problem with supplying the unit from a 5-pin 16A RCD socket as the heater elements although separately controlled will be roughly in balance (similar load) and the ELV parts will be a negligible (single phase) load in comparism.
My thoughts on packaging are that the different voltages present should be separated adequately (different enclosures,double insulation, sheathing etc) and that the steel casing should be of course adequately earthed.
Also I have thought that a 'fail safe' thermal trip operating an 'upfront' contactor might be advisable.
Any other thoughts? other than run a mile, which is kind of what I am expecting...

View attachment 43830

if he has designed this thingymajig that could not be sourced from ANYWHERE then why is he still working in a kitchen?!?!?

 

[Adam W]

As always I would recommend researching what everyone else uses instead of trying to be ingenious.
Something like this maybe? Marlen International Companies - https://marlen.com/post_products/industrial-dehydrator/

Or if he wants something a bit more 'Heath Robinson' maybe set aside a drying room like they have on construction sites when it's raining - a couple of convector heaters and Argos dehumidifiers should do the trick.

 

[grumpyjohn01]

As always I would recommend researching what everyone else uses instead of trying to be ingenious.
Something like this maybe? Marlen International Companies - https://marlen.com/post_products/industrial-dehydrator/

Or if he wants something a bit more 'Heath Robinson' maybe set aside a drying room like they have on construction sites when it's raining - a couple of convector heaters and Argos dehumidifiers should do the trick.

OK dumb might be a bit harsh but really your second suggestion is at least daft. The first suggestion is more like it but out of the scope of this scenario.

 

[grumpyjohn01]

This little project would be right up my street but unfortunately Dorset is out of my local reach, I see a few questionable design issues already that would impact the ability for a even temp' across the unit, I was involved many years ago with the an oven design that had to maintain a equal temp' throughout it was a critical application used in the aviation industry and temperature control had to be even and precise to the degree.
That aside you also need to realise this will not come under the BS7671 and will fall into the machinery standards, there are strict regulations and will affect everything from design, control and system safety, there are no short cuts, you cannot make a functional unit without adhering to the standards, if this was a garage project to test the concept then yes but if this is indeed going to be trialled and used by staff, employees or other third parties then it will have to meet all standards and be certified, also it may have to comply to food safety standards too, this may be covered if this falls within a specific area of the machinery control standards.

I understand the temptation to get involved but I would keep well away as your involvement would put the responsibility of the control system on you shoulders regardless of any promises made, I take it you will not be covered on your insurance for this and it could void your existing cover if you are found to be working on equipment/systems that you have not declared to you insurer.

I would suggest he seeks a local machinery control designer who will be able to provide all the design, cert's, wiring schematics etc as required for such a system.

Thanks for your input, I have now read some of your earlier posts and am in total agreement. I always had reservations over my involvement in that aspect. We now have touched base with another forum member who is willing to help.

 

[Adam W]

OK dumb might be a bit harsh but really your second suggestion is at least daft. The first suggestion is more like it but out of the scope of this scenario.

Why? They do it with fridges, freezers and propagators, why not dehydrators?

 

[grumpyjohn01]

Why? They do it with fridges, freezers and propagators, why not dehydrators?

Yes it can be done I'm sure but it wouldn't be suitable in this case. The food product that is being made here is unique in the market and requires dehydrating in a controlled manner. My client has been developing his methods for some time and has tried various commercially available machines, some of which have cost large sums. None of them have performed any where near as well as his ' Heath Robinson' machine. He has been testing it for some time with a bespoke monitoring system which guess what, he designed & built himself. He could bore you for many hours with graphs & data & stuff...

 

[Adam W]

Well good luck to the two of you on whatever it is you're trying to do.