Designing a Heater Control Valve - Sealing Issues.
Discussion
Hi guys,
I am not sure where this belongs but I am after some engineering advice.
I am currently designing a heater control valve operated by an RC servo which is to be sold on my aftermarket heater webstore.
Heater control valve specification:
CNC machined aluminium housing.
Lasered alu butterfly valve.
Stainless shaft to rotate butterfly.
Ok so the problem I have is working out the best way to seal the stainless shaft against the alu housing to prevent leaks, so can anybody recomend a place that will sell off the shelf seals that will do exactly what I need.
How do existing heater control valves seal the rotational shafts?
Many thanks,
Mudgey
I am not sure where this belongs but I am after some engineering advice.
I am currently designing a heater control valve operated by an RC servo which is to be sold on my aftermarket heater webstore.
Heater control valve specification:
CNC machined aluminium housing.
Lasered alu butterfly valve.
Stainless shaft to rotate butterfly.
Ok so the problem I have is working out the best way to seal the stainless shaft against the alu housing to prevent leaks, so can anybody recomend a place that will sell off the shelf seals that will do exactly what I need.
How do existing heater control valves seal the rotational shafts?
Many thanks,
Mudgey
....were my initial thought, however I do not think they would be up to the job. I am now thinking along the lines of an oil ring seal with an internal metal spring to put pressure on the surfaces and will allow for rotational movement of the stainless shaft. I have found suitable oil rings but they are £1.40 a pop which is waaayy too much and I am unsure how well they would cope with a liquid less viscous than oil.
Is there anybody out there that has experience with seals and would b able to sat what would and wouldn't be adequate?
Is there anybody out there that has experience with seals and would b able to sat what would and wouldn't be adequate?
Edited by Mudgey on Tuesday 13th April 21:37
Your valve sounds to me like a variation on the same theme as the ball valves which are used to connect washing machines, only with a butterfly instead of a ball... Those valves use O-rings to seal, so I'd be surprised if they wouldn't do for yours too. Are you worried about frequent valve operation wearing them out? Would have thought it would be OK with a good finish on the shaft.
Why re-engineer something so simple..
Get a bog standard thermostatic radiator housing... unscrew the thermostat bit... you are left with a spring loaded rod sticking up at you... press it down to close the radiator... let go to allow flow..
A simple lever arrangmenet from your servo would be more than enough to close it off..
If you were after something larger... a motorised gate valve would also work...
Get a bog standard thermostatic radiator housing... unscrew the thermostat bit... you are left with a spring loaded rod sticking up at you... press it down to close the radiator... let go to allow flow..
A simple lever arrangmenet from your servo would be more than enough to close it off..
If you were after something larger... a motorised gate valve would also work...
I think using two compressed O-rings may possible be ample, however I would need to design in a threaded boss to compress the O-rings against the shaft and such. The current design as seen in the picture was designed around an oil seal which is rather large.
This design is RC servo operated, has a two piece mounting system which has a footprint within the overall dims of the unit and has 3/8BSP threads either end so a number of popular sized barbs may fit.
I am currently awaiting prices from a Chinese company I normally use to do my CNC parts.
This design is RC servo operated, has a two piece mounting system which has a footprint within the overall dims of the unit and has 3/8BSP threads either end so a number of popular sized barbs may fit.
I am currently awaiting prices from a Chinese company I normally use to do my CNC parts.
Throwing this in just for the hell of it..
Old fashion way of doing it would be to use leather seals. swells but also shrinks if dry.
http://www.copperwasher.co.uk/leather.html
Old fashion way of doing it would be to use leather seals. swells but also shrinks if dry.
http://www.copperwasher.co.uk/leather.html
Edited by 69 coupe on Thursday 15th April 22:27
If you're designing in a threaded boss, then you can use valve stem packing material (there are many to choose from)
http://www.gore.com/en_xx/products/sealants/packin...
What about corrosion issues between the ali and stainless?
http://www.gore.com/en_xx/products/sealants/packin...
What about corrosion issues between the ali and stainless?
The CNC'd alu parts would be anodised, but also the shaft will most probably be made out of alu as it is both cheaper and would be more than up to the job it is required to do. This should prevent any issue with corrosion.
It seems as though this HCV mini project is going on the backburner until I can figure out how well Servo's can last when connected to something thats about 90c, however I am shocked at how cheaply our friends in China can knock this stuff out at!
For the minute I am concentrating on a PCB that can control fans & 2 sets of servo's for the heater unitspictured below.
It seems as though this HCV mini project is going on the backburner until I can figure out how well Servo's can last when connected to something thats about 90c, however I am shocked at how cheaply our friends in China can knock this stuff out at!
For the minute I am concentrating on a PCB that can control fans & 2 sets of servo's for the heater unitspictured below.
Edited by Mudgey on Monday 19th April 15:33
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