Automation software/hardware

[bernardgreen]

Relying on mobile phones just ringing could leave you literally in the slurry.

At the time you are connecting the pipe work there is a wrong cumber call to the pump's phone and the pump starts.

Or as you bend down to the pipes the buttons on the phone in your pocket get accidently pressed.

Include an SMS command would make it less hazardous.

Or the pump needs to be stopped but you cannot get a signal.

 

[SimonH2]

Agreed, it all depends on the risk factors. As pointed out, many remote control solutions would also have issues - range, interference, etc.

Another reasonably cheap, and long range (long enough for this) would be CB (or one of the licence free walkie talky frequencies) and some tone switches. It's fairly easy to put together a system where pressing a button on one unit, keys the transmitter and sends audio tone(s). At the receiving end, it's a fairly simple matter of taking the aurio out and listening for the tones.
DTMF is probably sufficiently reliable, especially if you setup a system that needs a code sequence rather than single code to start - false stops are not dangerous in this situation, just false starts.

PS - I know someone who disconnected a pipe with the pump running. In this case, it was a PTO (mechanical drive shaft) driven lift pump lifting the manure from a sump to either fill the tanker or recirculate to the store. The person in question was used to putting the tractor to idle - a speed where the pump couldn't lift the manure to the pipe connection while he swapped pipes over.
One day he was using a different tractor, one with multi-power and those who have driven them will know that MFs with multi-power idle at around 900RPM instead of 300. 3x the idle speed, pump output goes at something like square of speed, I think you can see what went wrong when said person flipped off the retaining collar.

Oh to have been there - at a safe distance of course

 

[bernardgreen]

I was working on a Thames Sludge Tanker, a floating tank that takes sewage from the London Sewage Treatment to be dumped at sea, when one of the high pressure delivery hoses detached from the manifold on the ship. The auto shut down was slow to react. Very messy.


Using DTMF sequences over PMR 446 would be a good way to go. ( provided the actual PMR unit is not modified, all connections via its ear., mic and remote PTT switch sockets ).

And once started the pump runs for a set time and then stops unless a continue message is received to restart the timer.

 

[JohnW2]

And once started the pump runs for a set time and then stops unless a continue message is received to restart the timer.

In the sort of applications we're talking about, one surely needs a 'fail safe' system such as that (even if that is regarded as 'safe enough')? Relying on a "stop" signal (however transmitted/conveyed) being received and properly acted upon is surely fraught with far too many possible modes of failure?

Kind Regards, John

 

[SimonH2]

I would go for a start-message, stop-message, and auto-stop if a start-message isn't received every so often.
One thing you must not do with these wireless systems is transmit continuously as that would, I believe, be considered abuse and outside the use permitted by the licence exemption. Put another way, don't hog the channel !

 

[Simon35]

And once started the pump runs for a set time and then stops unless a continue message is received to restart the timer.

In the sort of applications we're talking about, one surely needs a 'fail safe' system such as that (even if that is regarded as 'safe enough')? Relying on a "stop" signal (however transmitted/conveyed) being received and properly acted upon is surely fraught with far too many possible modes of failure?

Kind Regards, John

There are ways of deisgning safety related controls, detailed in the relevant standards, that need to be adhered to. Along with producing the relevant design documentation to show that the designed system meets the requirements identified by risk assessment. Along with testing the system to ensure it meets those requirements.

Talk of using a CB and listening for tones isn't going to cut it when it all goes wrong and the HSE have shut your business down, are reaming you, and wanting to fine you £10000's.

 

[SimonH2]

TBH, a radio system is probably no more (or less) risky than having a bored operator sat on a tractor - who probably can't see the active operations most of the time, and even when he can will have his mind (and eyes) on something else anyway.

 

[JohnW2]

I would go for a start-message, stop-message, and auto-stop if a start-message isn't received every so often.!

That's exactly what bernard (and I) were talking about - except that he called it (more correctly) a "continue" message, rather than a "start" one.

Kind Regards, John

 

[Simon35]

TBH, a radio system is probably no more (or less) risky than having a bored operator sat on a tractor - who probably can't see the active operations most of the time, and even when he can will have his mind (and eyes) on something else anyway.

The radio system is a non-starter, unless you can determine it's reliability, by which I mean attach some actual numbers based on evidence (mean time to failure etc etc).

If it's the job of the tractor driver to emergency stop the system, then the supplier of that emergency stop pushbutton will provide the figures, as will the supplier of the safety relay monitoring the pushbutton, and the supplier of the safety contactor to remove power.

 

[JohnW2]

TBH, a radio system is probably no more (or less) risky than having a bored operator sat on a tractor - who probably can't see the active operations most of the time, and even when he can will have his mind (and eyes) on something else anyway.

Indeed. One would hope that would be taken account in a (realistic, rather than 'idealistic') risk assessment.

Kind Regards, John

 

[SimonH2]

The radio system is a non-starter, unless you can determine it's reliability, by which I mean attach some actual numbers based on evidence (mean time to failure etc etc).

If it's the job of the tractor driver to emergency stop the system, then the supplier of that emergency stop pushbutton will provide the figures, as will the supplier of the safety relay monitoring the pushbutton, and the supplier of the safety contactor to remove power.

You have a strange idea of how agricultural systems work. There will be no e-stop button - just manual controls. So once the pump is set running, it'll run until it's either stopped (manually) or the tractor engine stops.
That's generally how most agricultural machinery works.

Manning the pump will be a really boring job - you just sit there, start it when needed, do nothing for <some period of time>, stop it, rinse and repeat ... - whoever gets that job isn't going to be the most alert and motivated person around. So you've got a human with a boring task and lots of free time. You can reasonably expect these days that their attention will mostly be on a mobile or something like that. So overall, I'd say a radio system stands a good chance of being more reliable - it'll be hard to make it less reliable

 

[deadshort]

Had a bit of a think. And memories of a burst slurry pipe remind me there is a need to ensure pump can be stopped when necessary.

Since there is a flexible pipe connecting the two tractors would it not be possible and maybe more reliable to run a cable with the pipe.

The cable could be taped onto pipe sections with connectors so it is laid out as the pipes are laid out..

Feed 12 or 24 volt DC from the spraying unit via the cable to the coil of a relay on the pump unit. The pump only runs when that relay is energised. Mr green, you are the man ! Information, facts, and advice ! A1 sir !

DS



If using radio then a "keep pumping" signal should be sent at regular intervals when pumping is needed. If communications fail then the pump will stop when there is a gap in the "keep pumping" messages.

 

[stillp]

If using radio then a "keep pumping" signal should be sent at regular intervals when pumping is needed. If communications fail then the pump will stop when there is a gap in the "keep pumping" messages.

This is a requirement of the Machinery Directive, implemented as the Supply of Machinery (Safety) Regulations. The maximum delay is determined by a risk assessment.

 

[ban-all-sheds]

Had a bit of a think. And memories of a burst slurry pipe remind me there is a need to ensure pump can be stopped when necessary.

Since there is a flexible pipe connecting the two tractors would it not be possible and maybe more reliable to run a cable with the pipe.

The cable could be taped onto pipe sections with connectors so it is laid out as the pipes are laid out..

Feed 12 or 24 volt DC from the spraying unit via the cable to the coil of a relay on the pump unit. The pump only runs when that relay is energised. Mr green, you are the man ! Information, facts, and advice ! A1 sir !

DS



If using radio then a "keep pumping" signal should be sent at regular intervals when pumping is needed. If communications fail then the pump will stop when there is a gap in the "keep pumping" messages.

No he didn't.

 

[bernardgreen]

To B A S

I did write most of that, D S got the quoting wrong.