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Vacuum Pump Control

Posted: 12 Feb 2021, 17:09
by Mick Tomlin
During the first lockdown I read an article on building a digital control vacuum gauge and pump switch.

https://www.rcgroups.com/forums/showthr ... uge-Switch

So having some time on my hands I decided to build one.
Other than wiring multi wing servos this was my first attempt at constructing electronic gadgetry.
It has been used to vacuum bag some 2mt wing panels.
Set at 15inHg max with 13inHg low settings the pump ran 4 times for total of 27 second during a 12 hour cure.
Attached are some pictures of the setup.
It is compact, quiet in operation and did not cost a lot to build.
Definitely worth considering if you are into vacuum bagging.
Mick
SH100520.JPG
SH100521.JPG
SH100524.JPG
SH100527.JPG

Re: Vacuum Pump Control

Posted: 18 Feb 2021, 18:30
by paulj
That looks great Mick!

Re: Vacuum Pump Control

Posted: 18 Feb 2021, 18:58
by Mick Tomlin
Thanks Paul
It works very well and the vac control has to be seen.
Get the bag sealed and it hardly runs tops up at all.
Ideal for me as I use a spare bedroom for building and have to keep noise under control.
Where it would be a great help is if you use a pump that emits an oil mist as this set up runs so infrequently it would reduce that to an absolute minimum.
Not that expensive to construct either and the build guide is superb, I did it as my first electronic build.

Mick

Re: Vacuum Pump Control

Posted: 18 Feb 2021, 19:06
by Peter Balcombe
The linked RC Groups thread also has a 20x4 LCD option which I have looked at as this is able to display all data in just 3 screens rather than many more.
As the available firmware uses nearly all available program & memory resources, plus the need to have 2 twiddle pots for vacuum threshold/switching margin inputs, I have also tweaked the firmware to allow the user to compile a single vacuum measurement unit (mBar, mmHg, inHg) rather than select any one at any time, plus replaced the 2 pots with a single rotary encoder switch to toggle between Threshold/Margin value selection.
The compiled code now only uses about 50% of the Arduino resources, so should be more stable.
I’m just about to start packaging the controller into a plastic box, together with 12v psu, sensor & 2 relays. Hopefully it will all fit.

Re: Vacuum Pump Control

Posted: 18 Feb 2021, 19:16
by Mick Tomlin
Peter
That looks very good indeed and your idea of getting more info shown is excellent.
How long have you been working on the controller and would you be prepared to share the upgrades that you have made.

Regards Mick

Re: Vacuum Pump Control

Posted: 18 Feb 2021, 19:38
by Peter Balcombe
Hi Mick,
The displays are basically exactly what you should get with the 20x4 display version of the latest software version (there is both a 16x2 & 20x4 version of the software - look for version 4.0.0 in the latest page or so of posts, so it may be worth you looking at the 16x2 display version of that if not already there.
I think the 16x2 version can display similar data to the 20x4, but obviously has to cycle through more display screens to show it all.
The original program is very versatile & I think it allows you to even choose what data to put on which screen ‘page’.
In fact I thought the original program to be a little too versatile, making the program overweight. For instance, I thought that users would have a favourite pressure value unit & always stick to that in practice.
You mentioned inHg in your post, but I would probably always use mBar.

I only picked up on the controller program last weekend & once I quickly had it running on an Arduino Uno & I2C 20x4 display that I had lying around, I decided to try replacing to 2 pots - but needed more processor resources, hence first slimming down by compiling for only one measurement unit.
I had used the encoder method of input before on a much simpler controller.

I am more than happy to share my updated versions, noting that they are currently only for the 20x4 display - although it’s probably not a big job to tweak the 16x2 version as well if needed.
The way the program is written, I think only the display.info file would need to be changed from my encoder version apart from redefining the display setup in the LCD setup part of the main sketch.
Peter

Re: Vacuum Pump Control

Posted: 18 Feb 2021, 21:48
by Peter Balcombe
Mick,
Did you use std. 4” PVC soil pipe & end caps for your large reservoirs?
What did you use for the smaller one (2”)?
It looks as if you have your smaller reservoir on the pump side of the check valve & a solenoid operated dump port with silencer fitted. Is that correct?
Thus it appears that you open the solenoid dump valve to remove any load on the pump when it starts, then close the solenoid valve & pull vacuum on small reservoir before check valve opens to pull on the rest of the system?

Mick, I assume that you are using an I2C display rather than a parallel interface type. I have seen a schematic for parallel but the firmware all seems to be for I2C.
Peter

Re: Vacuum Pump Control

Posted: 19 Feb 2021, 10:21
by Mick Tomlin
Hi Peter
My using Hg readings probably gives my age away.
Having thought about changing the display I think I will stay with what I have.
My build was not without some frustration with the controller, about a week to fathom out how to get the display to work.
Once that was sorted all worked and is still working very well so best to leave well enough alone.
Your upgrade to the firmware could well be of benefit to others that may build one.
The pipe that I used is solid wall soil pipe with suitable end caps.
The reservoir consists of 2 x 100mm x 300mm pipes and the relief tank 200mm x 1.5 in. waste pipe, all fitted and sealed with suitable end caps.
All of the metal fittings were BSP, the only problem that I had with the plumbing was getting an airtight seal on the thru tank fittings. This I cured with two hydraulic sealing washers with a slimmed down nut locking them on the inside of the end caps.
I had a Thomas pump in the corner and used that. The analogue gauge was lying around so incorporated that as a reference guide to the display.
The pump is rated to 21Hg and as set up I have bagged 2mt wing panels with ease set at 16Hg high and 14Hg low.
The unit is leak free, getting the bag leak free is the frustrating part.
The vacuum pressure release is necessary if you do not want to stall the pump on restart. Was part of my learning curve.

Hope that helps
Mick

Re: Vacuum Pump Control

Posted: 19 Feb 2021, 11:28
by Peter Balcombe
Thanks for the info Mick.
I2C displays sourced from different suppliers can use various I2C addresses (e.g. mine uses 0x27 instead of the 0x38 used in the default sketch).
However, a device address is easily found by loading a sketch called I2C scanner which lists (on the PC screen by selecting the serial terminal display, with the correct baud rate) the addresses of every device found on the I2C highway.

There are also different LCD I2C libraries out there, but using the specified one should work ok straight away if the I2C address is correct.
It appears that you can get more display screens up by cycling through them with quick clicks on the pushbutton - at least on the later posted version of the firmware.

Peter

Re: Vacuum Pump Control

Posted: 19 Feb 2021, 11:58
by Mick Tomlin
Peter
The address was my problem.
Got there in the end and learnt a lot. The plumbing was the easy part, my computer experience extends to turning them on and off.
Let us know how you get on and what your impression is when you have finished.
Mick

Re: Vacuum Pump Control

Posted: 20 Feb 2021, 23:56
by Philkiteflyer
Mick Tomlin wrote: 19 Feb 2021, 11:58 . . . . . my computer experience extends to turning them on and off.
Mick
You must work in our IT department . . . :lol: :lol: :roll:

Phillip C

Re: Vacuum Pump Control

Posted: 21 Feb 2021, 09:45
by Mick Tomlin
Yep
Employed to change the fuses

Re: Vacuum Pump Control

Posted: 21 Feb 2021, 10:57
by mjcp
I'm intrigued by this post as I had a hankering to re-purpose an old airconditioner's pump for bagging etc.

I am a little confused as to where the two grey cylinders are from. I assume they are tanks used to maintain some "store" of vacuum? (much like a compressor in reverse?)

Would my old ac unit have these? If not, where to source and are there guide line on volume / strength etc to be followed?


thanks in advance!

M

Re: Vacuum Pump Control

Posted: 21 Feb 2021, 12:27
by Mick Tomlin
Mark
This set up should work with any pump arrangement as it basically controls the power to the pump.
Only thing to take note of is the start up currant for you pump and ensure that the relay is man enough,
The small white tank is 1nch water pipe and acts as a check to stop the pump trying to start with a vacuum as this it can stall the pump.
The two gray tanks I used some soil pipe that was lying around with end caps. Each is 100mm diameter x 300mm length
They give some back up vacuum that smooths the operation and aids having to run the pump more than necessary.
I bagged some 1.75mt wings and with a good seal on the bag the pump ran for less than 30 seconds over the 12 hours.
To give some idea of scale my unit measures 400mm wide, 250mm deep. 300mm high.
Hope that helps
Mick
By the way the wings are for my PIK 20.

Re: Vacuum Pump Control

Posted: 19 Nov 2021, 20:06
by mjcp
Me again... back on the vacuum idea.

Over the summer we had the mis-fortune of our portable ac unit failing.. luckily the compressor stayed hear while the rest went to the tip; my hope is I can use the compressor as a vacuum pump?

Do I have the right idea or is this a bit beyond possibility?

Pump specs (Link to PDF on ext. site)


IMG_2202.jpeg
IMG_2203.jpeg
IMG_2204.jpeg

Re: Vacuum Pump Control

Posted: 19 Nov 2021, 21:33
by Peter Balcombe
Marc, there are plenty of uTube videos on converting a fridge compressor into a vacuum pump, so I guess your compressor is essentially a bigger version of a fridge unit?
Just need to identify which pipe is ‘suck’ & which is ‘blow’.
Make sure you have all the starter electrics & know what you are doing regarding electrical safety - else make sure you get a competent person to look after that bit :)

Having just looked at the data sheet, I see this is a rotary type, but I guess it should work ok as long as you have a non-return valve in the system (unless there is already an internal one)?

Re: Vacuum Pump Control

Posted: 23 Nov 2021, 17:38
by mjcp
Thanks Peter,

Not sure about the non return - trial an error should confirm that! As for the electrics... 25+ years in IT.. I haven't zapped myself yet ;)

I assume these are designed for a specific refrigerant i.e. R-407c in this case. Is there an issue in the conversion where its now pumping/sucking air? Does the refrigerant offer any lubrication or sealing properties to the pump ? (or are we assuming little use/hobby use and therefore minor issue over time?)

Marc

Re: Vacuum Pump Control

Posted: 23 Nov 2021, 19:14
by Peter Balcombe
Marc, from what little I know/have seen on the web about A/C rotary compressors, they probably cope with any gas refrigerant - it’s just that the R407c is possibly the one the compressor was type tested with. Car A/C units seem to use one of 2 types of gas & it may depend on what was current when the car was manufactured?

As far as I can make out, the (normally) gas comes in via the side unit which contains a particle filter & the ability to retain/boil off any liquid coolant which happens to make it from the condensing (cooling) coils.
The pump data sheet does mention oil, but I expect that is in there to lubricate/cool the pump mechanics.
The exhaust (pressure side) seems to be the top tube which normally goes off to the evaporator coil (an external unit with fans) to get rid of the heat extracted by the cooling coils + pump compression heat.

Typical A/C arrangement
Typical A/C arrangement

Your pump is pretty powerful compared to a normal piston type fridge compressor, so able to shift a lot of gas/air. You might need to be able to start the pump & let it get to speed before trying to put on load. You can do this by opening a pump relief valve for a short time each time the pump starts, letting it get up to speed.
Even more important to use reservoir tanks with this pump methinks.
Peter

Re: Vacuum Pump Control

Posted: 24 Nov 2021, 19:00
by Mick Tomlin
Hi Mark.

Peter is correct and your compressor pump will probably work very well.
How do you intend to control the vacuum as this is the issue when bagging composites, especially foam core items.

Mick

Re: Vacuum Pump Control

Posted: 24 Nov 2021, 19:22
by Peter Balcombe
This is where the thread started, based on the RC Groups vacuum controller thread.

The controller uses a small Arduino processor unit to sense vacuum level & control pump run/manifold valve operation via a couple of relays to keep the vacuum within defined limits.
One relay switches the pump on/off whilst the other operates a solenoid valve to take the pump off load (if needed) whilst it runs up to speed.
The reservoirs should greatly reduce the number of times the pump needs to run once the required vacuum has been pulled on the bagged components during the cure time.

Re: Vacuum Pump Control

Posted: 07 Dec 2021, 20:16
by mjcp
Thanks for the responses, sorry for the delay!

Parts ordered...

M

Re: Vacuum Pump Control

Posted: 07 Dec 2021, 20:44
by Peter Balcombe
Marc,
Let me know where you get your tube for the reservoirs as I’ve been wondering where to find the lengths needed without having to buy several metre lengths for the sake of a few 100mm.
Peter

Re: Vacuum Pump Control

Posted: 07 Dec 2021, 23:18
by mjcp
I have a friend who runs a plumber's merchant ;-)

What should I ask for / do I need? (It's the electronics that have been ordered so far)

M

Re: Vacuum Pump Control

Posted: 08 Dec 2021, 09:28
by Peter Balcombe
Marc
The attached U.S. based project seems to be pretty helpful.
They used a 4” soil pipe for the main reservoirs & 2” pipe for the auxiliary.
These need to be thick walled to withstand the vacuum pressure & have end caps that you can put fittings into - probably the uPVC cement welded type.

instructions-ProjectEVS.pdf
(1.28 MiB) Downloaded 97 times

Re: Vacuum Pump Control

Posted: 08 Dec 2021, 20:25
by mjcp
Here's my parts list (so far) - £53 (Dec 2021, UK sourced)

I already have the Arduino Nano and assorted wires/tools etc on hand.
Pipe work and fittings TBN.

Pre Wired LEDs 5mm Diffused 5V-12V with Metal Holder Prewired UK Seller (Red)
https://www.ebay.co.uk/itm/183044754194 ... 0343201842

MPX5100DP Freescale Semiconductor IC, Sensor, Diff Press 14.5 Psi
https://www.ebay.co.uk/itm/133935106866

With/Without IIC/I2C 2004 20X4 Character LCD Module Display Blue Green Arduino
https://www.ebay.co.uk/itm/263128525818 ... 4776646463

4 x 10K Linear Lin Potentiometer Pot with Coloured Knob
https://www.ebay.co.uk/itm/252305055054

Standard Size Toggle Switch Screw Terminals 10A 250VAC - Double or Single Pole
https://www.ebay.co.uk/itm/263095161859 ... 2094605473

Solid State Relay Module SSR-40DA 40A, 3-32V DC to 24-380V AC, With safety Cover
https://www.ebay.co.uk/itm/154355099253

IP65 Waterproof Electronic Project Box Enclosure ABS Plastic Case Junction Box
https://www.ebay.co.uk/itm/384066470987

Arduino Nano V3.0 Prototype Shield Extension Board I/O Expansion Module -UK
https://www.ebay.co.uk/itm/194257659890

Re: Vacuum Pump Control

Posted: 08 Dec 2021, 20:26
by mjcp
I was a little surprised at the price of the pressure sensor (MPX5100DP) - £20. The single most expensive component of the lot!

M

Re: Vacuum Pump Control

Posted: 09 Dec 2021, 09:07
by Peter Balcombe
Marc, it looks as if the price has nearly doubled during the year as I bought mine for £10.48 back in February :(

Re: Vacuum Pump Control

Posted: 10 Dec 2021, 16:04
by mjcp
Despite the xmas rush and choosing the cheapest delivery methods, all the parts turned up today!

Not really knowing how big the box needed to be, I'm glad it fits in the project box!
IMG_0648.jpeg

M

Re: Vacuum Pump Control

Posted: 11 Dec 2021, 11:39
by Mick Tomlin
Mark the pictures at the beginning of this thread give a good idea of the fittings required and their configuration.
I used 1/4 inch BSP fittings that are readily available.
The only small problem I had was getting a good seal with the thru tank fittings on the two vacuum reservoir tanks.
Resorted to doubling up the thickness of the end caps with scrap plastic poly welded to the inside and tapping to accept the barrel fitting.
Hydraulic sealing washers were then used on the inside to complete the seal.

Hope that helps and good luck with the build.

Mick

Re: Vacuum Pump Control

Posted: 15 Dec 2021, 09:42
by Peter Balcombe
Mick,
I’m just assembling the reservoirs & pipework on mine, having managed to find an offcut of 4” soil pipe to make the main reservoirs.
Did you use standard 40mm or so waste pipe & caps for the small reservoir, or a more substantial variety?
Peter

Re: Vacuum Pump Control

Posted: 15 Dec 2021, 12:10
by Mick Tomlin
Peter

The small slave pipe is 1.5in waste pipe with stop ends at 8ins long.
For intended purpose this works just fine.
My pump is a Thomas rated to -21inHg.
Maybe for a bigger capacity system it would be worth enlarging to give it more capacity.

Mick

Re: Vacuum Pump Control

Posted: 16 Dec 2021, 15:21
by Peter Balcombe
Having now found a scrap length of 4” soil pipe, I see that the standard stop ends are £4.50 a throw at the local Master Plastics store! A clubmate has donated an old aluminium gas (may have been CO2) tank which is 110mm diameter & 300mm or so long & another has suggested old (empty) fire extinguisher tanks.

Looking on the web, I see that a 1L capacity dry power extinguisher tank is a similar size & can be bought new for £12 or so. A 0.6L tank is not much bigger than the sub-reservoir.
https://www.firesafety.uk.com/fire-ext ... inguisher/

Thus fire extinguisher type tanks may be a possible alternative to PVC pipe - although converting the outlet size may be more of a challenge!

Re: Vacuum Pump Control

Posted: 16 Dec 2021, 17:07
by Peter Balcombe
A quick calc shows that a 4” pipe 15” long is approx. 3L capacity.

Re: Vacuum Pump Control

Posted: 16 Dec 2021, 17:56
by Mick Tomlin
Peter

The total length of the two 4in. pipes on the system I constructed is 24.
2mt. wings have been done without any problems holding vacuum, that is after chasing and curing any leaks.
Personally I would go the pipe reservoir route as the unit will be a lot lighter and more compact for storage and moving about.

Mick

Re: Vacuum Pump Control

Posted: 16 Dec 2021, 20:03
by Peter Balcombe
Mick, I got hold of an Aluminium cylinder approx. 4” diameter & 300mm or so high at the neck which started me looking at gas cylinders as a possibility.
You’re probably right in that most extinguisher cylinders are steel & heavier. However, I’ve just found a possible source of 110mm x 400mm ish ones, so am hopefully getting a couple to try for <£10.
The PVC end caps alone were going to cost £20!, but I could still go that route.

I will report back in due course - maybe with a bad back :o
Peter

Re: Vacuum Pump Control

Posted: 17 Dec 2021, 09:33
by Mick Tomlin
Peter
If you want to go the metal cylinder route how about one of the 7Kg capacity lightweight propane cylinders.
These are being fazed out and no longer eligible for refill.
It may be possible to pick one up for scrap price or free from a local bottled gas supplier.
Ally construction and very light.
Mick

Re: Vacuum Pump Control

Posted: 18 Dec 2021, 02:25
by Philkiteflyer
Peter Balcombe wrote: 16 Dec 2021, 20:03 Mick, I got hold of an Aluminium cylinder approx. 4” diameter & 300mm or so high at the neck which started me looking at gas cylinders as a possibility.
You’re probably right in that most extinguisher cylinders are steel & heavier. However, I’ve just found a possible source of 110mm x 400mm ish ones, so am hopefully getting a couple to try for <£10.
The PVC end caps alone were going to cost £20!, but I could still go that route.
This option brings to mind 'Failed' Aluminuim skuba tanks. They would be lighter than steel for sure but I know nothing about volume / weight etc.
If you have a dive shop close by, maybe worth a try ? ? A quick google found this add in NZ https://divedoctor.co.nz/product/catali ... ith-valve/ I'm sure they would last longer than plastic.

Cheers from NZ,
Phillip C
Invercargill

Re: Vacuum Pump Control

Posted: 25 Nov 2022, 21:54
by mjcp
Its been *almost* a year since I ordered parts for the controller, so I guess I ought to use them...

My controller will be portrait so the innards fit a little easier.
IMG_4491.JPEG
IMG_4492.JPEG


Time for some very satisfying time with one of my favourite toys, erm, tools and a bit of hand filing to fine tune.
IMG_4498.JPEG
IMG_4502.JPEG


The stand-offs used and the screen is mounted.
IMG_4507.JPEG
IMG_4506.JPEG

Re: Vacuum Pump Control

Posted: 25 Nov 2022, 22:06
by mjcp
Next up, the controls, checking they don't conflict with the innards.
IMG_4514.JPEG
IMG_4517.JPEG
IMG_4520.JPEG


Once drilled, the rotary dials needed an additional rebate to locate them flush.
IMG_4521.JPEG
IMG_4522.JPEG
IMG_4524.JPEG


All good. On to the innards next. (with luck, it wont be another year!)
IMG_4530.JPEG
IMG_4532.JPEG

Re: Vacuum Pump Control

Posted: 26 Nov 2022, 22:57
by mjcp
Progress.

Are these values expected on boot? (nothing attached to the two sensor tubes, they're exposed to ambient)

Vacuum: 000 mBar

Threshold -500 / -600 (both knobs fully /down)
(and -930 / -950 with both knobs turned full /up)

Pump timer 24:00:00

(need to source a switch, I missed that from the original order!)
IMG_4543.jpeg

Re: Vacuum Pump Control

Posted: 30 Nov 2022, 11:27
by Mick Tomlin
Hi Mark
Very neat looking construction.
The reading that you are getting are correct if taken on open tube lines.
The vacuum thresholds, high and low, can be adjusted with the pots.
It is also possible to adjust to actual atmospheric pressure when all connected up.
I incorporated a vacuum gauge into the one that I built to give a cross reverence to the vacuum being pulled.
What are you going to use for the tanks.

Mick

Re: Vacuum Pump Control

Posted: 01 Dec 2022, 16:59
by mjcp
Thanks for the positivity, Mick!

I've had a quick look on gumtree and there's no free fire extinguishers locally, so "plan b" will be to follow your method and use 4" pipe. Was yours just the standard grey soil pipe? (I saw a nice looking DIY pump on a YT video where the pipes had nice domed caps, but I can't see those in the UK :( )

M

Re: Vacuum Pump Control

Posted: 02 Dec 2022, 17:22
by Mick Tomlin
Hi Mark
The pipe that I used is standard solid wall 4 inch waste pipe with suitable cap ends that fit. Beware that not all 4 inch cap ends are the same. Must be solid wall and not the egg box inner wall type pipe.
An alternative method would be a lightweight propane gas cylinder. These are being phased out and scrapped and it may be possible to get one from a local dealer.
You will have to be very careful and make sure that you purge it of all vapour before converting it.
Carefully remove the top fitting and fill and flush with water is one method, the other method could well singe your eyebrows
A 7kg bottle will be more than ample for your requirements and weighs next to nothing being aluminium.
Mick

Re: Vacuum Pump Control

Posted: 05 Dec 2022, 16:12
by mjcp
I've noticed a slightly odd symptom:


When the toggle button for the pump is triggered, the pump run time counts as expected and the pump relay works is /ON solid.

So far so good...

But, with the toggle UN-triggered, the pump LED (and the relay / pump control) flashes on/off together with the warning LED. Additionally, the counters count down 1 second and then flash / reset back to their starting points.


Any ideas anyone?

M

Re: Vacuum Pump Control

Posted: 05 Dec 2022, 18:21
by Mick Tomlin
Hi Mark
Are you pulling a vacuum when this happening ??
Mick

Re: Vacuum Pump Control

Posted: 21 Dec 2022, 12:14
by mjcp
Mick Tomlin wrote: 05 Dec 2022, 18:21 Hi Mark
Are you pulling a vacuum when this happening ??
Mick

Sorry for the delay!

No, just bench running with nothing else attached.

Marc