[Tim S]

This looks very interesting:

http://www.floodcheck.co.uk/store/in...d&productId=29

Haven't managed to contact them yet (no answer) but it did make me wonder:

I wonder where they got their water valve/actuator from...

Reading around the website, it's a 9v MOMO valve (ie needs power only when
changing state) - I suspect therefore it's a motorised ball valve rather
than a solenoid.

I could see a use for the valve alone. If the whole thing costs 42 quid, the
valve must be in the region of 30 quid.

Any ideas?

Cheers

Tim

[Tim S]

Tim S coughed up some electrons that declared:

This looks very interesting:

http://www.floodcheck.co.uk/store/in...d&productId=29

Haven't managed to contact them yet (no answer) but it did make me wonder:

I wonder where they got their water valve/actuator from...

Reading around the website, it's a 9v MOMO valve (ie needs power only when
changing state) - I suspect therefore it's a motorised ball valve rather
than a solenoid.

I could see a use for the valve alone. If the whole thing costs 42 quid,
the valve must be in the region of 30 quid.

Any ideas?

Cheers

Tim


To answer my own question:

Just had a call back from the designer (who I guess is also the owner). Very
interesting... They use a custom design latching solenoid valve, driveable
by pulse in the range of 6-24v. And he seems happy to sell the valves on
their own.

So I'd need a little interface timer that can apply the pulses based on a
general demand input (sounds like either a job for a 555 or an AVR/PIC
depending on your bent).

Low power (obviously), can handle low pressure at high temps too so good for
rads and the price indication I had is lower than my original guess.

0.5bar to 10bar, WRAS, 40l/min max flow - I can see a lot of applications
for this...

Like a PIR in the bathroom to operate the extract fan, but at teh sam etime
cut off the water to prevent flooding.

Or to stop the kids spending 20 hours in the shower

Cheers

Tim

[NT[_2_]]

On Jun 22, 9:54*am, Tim S wrote:
Tim S coughed up some electrons that declared:



This looks very interesting:

http://www.floodcheck.co.uk/store/in...d&productId=29

Haven't managed to contact them yet (no answer) but it did make me wonder:

I wonder where they got their water valve/actuator from...

Reading around the website, it's a 9v MOMO valve (ie needs power only when
changing state) - I suspect therefore it's a motorised ball valve rather
than a solenoid.

I could see a use for the valve alone. If the whole thing costs 42 quid,
the valve must be in the region of 30 quid.

Any ideas?

Cheers

Tim

To answer my own question:

Just had a call back from the designer (who I guess is also the owner). Very
interesting... They use a custom design latching solenoid valve, driveable
by pulse in the range of 6-24v. And he seems happy to sell the valves on
their own.

So I'd need a little interface timer that can apply the pulses based on a
general demand input (sounds like either a job for a 555 or an AVR/PIC
depending on your bent).

just wondering why a 555. All ac solenoids will run off dc, at IIRC
about half or 2/3 the voltage.


NT

[Tim S]

NT coughed up some electrons that declared:


Just had a call back from the designer (who I guess is also the owner).
Very interesting... They use a custom design latching solenoid valve,
driveable by pulse in the range of 6-24v. And he seems happy to sell the
valves on their own.

So I'd need a little interface timer that can apply the pulses based on a
general demand input (sounds like either a job for a 555 or an AVR/PIC
depending on your bent).

just wondering why a 555. All ac solenoids will run off dc, at IIRC
about half or 2/3 the voltage.


NT

Because it's a pulse driven latching jobbie.

The bloke said any attempt to continuously feed it will burn the coil out.

OK, 555 may be overkill, could probably do it by dumping a charged capacitor
into it using transistors to pump the charge through it.

I think this may be how the company use it - he mentioned using a 6.8mF
capacitor.

Anyway, with these valves, you bang a charge pulse through them one way to
turn on and the same charge through the opposite way to turn off. Do
nothing and they maintain their current state.

Me - it'd probably use a little 14 pin AVR microcontroller and as few
transistors as possible. They're like a quid, I'm setup to program them, I
can add a few failsafes (like if "call for water" is held high,
periodically send a refresher pulse to the valve every 10 minutes, just in
case it got stuck the first time (don't know if that ever happens), make
the valve "network" addressable too - RS485 being an easy choice) and any
other random funky stuff - probably all for a fiver, a bit of veroboard and
a little box all running off the 12V SELV supply that I need for other
things anyway.

Probably take a day or two to bang up a prototype that works.
And energy efficient to boot.

The only thing lacking is positive feedback that the valve is open or
closed,which is something you can of course have with a motorised zone
valve (mains operated at more cost too).
Cheers

Tim

[Jules[_2_]]

On Mon, 22 Jun 2009 09:54:21 +0100, Tim S wrote:
Just had a call back from the designer (who I guess is also the owner). Very
interesting... They use a custom design latching solenoid valve, driveable
by pulse in the range of 6-24v. And he seems happy to sell the valves on
their own.

Nifty. It's probably worth checking what testing's been done in terms of
estimating the number of cycles it'll stand before failing, as that'll
dictate what applications it can be used for.

Like a PIR in the bathroom to operate the extract fan, but at teh sam
etime cut off the water to prevent flooding.

Stuff like that makes me nervous in case the valve fails - it doesn't look
like it has any feedback as to current state, so you really need extra
gubbins 'downstream' to check that the valve has actually done what
you've asked it to.

cheers

Jules

[Tim S]

Jules coughed up some electrons that declared:

On Mon, 22 Jun 2009 09:54:21 +0100, Tim S wrote:
Just had a call back from the designer (who I guess is also the owner).
Very interesting... They use a custom design latching solenoid valve,
driveable by pulse in the range of 6-24v. And he seems happy to sell the
valves on their own.

Nifty. It's probably worth checking what testing's been done in terms of
estimating the number of cycles it'll stand before failing, as that'll
dictate what applications it can be used for.

This is a good point.

Like a PIR in the bathroom to operate the extract fan, but at teh sam
etime cut off the water to prevent flooding.

Stuff like that makes me nervous in case the valve fails - it doesn't look
like it has any feedback as to current state, so you really need extra
gubbins 'downstream' to check that the valve has actually done what
you've asked it to.

Indeed. Regarding the "flood prevention" - my view is that it doesn't make
the situation any worse than not having a valve (unless the valve itself
suffers catastrophic failure and ****es water everywhere - which hopefully
is a very unlikely scenario compared to "fails to control the water" mode
of failure[1]). So it's a net win.

[1] I'm expecting to see something loosely based on a washing machine valve
design with a clever drive mechanism - but I might be wrong.

However the lack of positive feedback is a pain, especially for diagnosing
problems - lack of control on a radiator (my main intended application)
will result in the room beiong either too hot or too cold.

I was thinking about this in the car this evening... The obvious solution is
to put a flow switch in.

This however is expensive and also prone to fail being a mechanical part.

So, I thought - seeing as I'm going to whack an AVR microcontroller next to
the valve, why not stick a temperature sensor on the output pipe next to
the valve? Could be a Dallas 1-wire jobbie (I like them and have driven
them from AVRs with excellent success) - or even a thermistor and use the
AVR's A/D converter.

In any case, one would expect 2 things of the temperature on a pipe:

a) When valve is closed, output pipe temperature should tend towards room
temperature over time, where I might expect a time constant of minutes;

b) When open *and* downstream is accepting flow (always with a rad,
intermittently with taps/shower/etc) then the pipe temperature is either
going to hit perhaps 10C or less (mains cold) or 50C+ (hot water). These
are pretty extreme temparture changes to be looking for and I think should
give a reliable indication of the radiator valve working. For flood
prevention, one should expect a reliable indication that there is no flood,
but one will never be sure *all the time* if the valve is opening
correctly, but you will get indications *some of the time* (tap on) so
could do long term analysis and flag up a failed valve.

SMWBO taking a cheesegrater to my nuts after the shower lost hot water of
course is the 100% reliable indicator the valve died(!)

I'll ask the bloke if I can buy one for a sample and test it...

Cheers

Tim

[NT[_2_]]

On Jun 22, 1:54*pm, Tim S wrote:
NT coughed up some electrons that declared:

Just had a call back from the designer (who I guess is also the owner)..
Very interesting... They use a custom design latching solenoid valve,
driveable by pulse in the range of 6-24v. And he seems happy to sell the
valves on their own.

So I'd need a little interface timer that can apply the pulses based on a
general demand input (sounds like either a job for a 555 or an AVR/PIC
depending on your bent).

just wondering why a 555. All ac solenoids will run off dc, at IIRC
about half or 2/3 the voltage.

NT

Because it's a pulse driven latching jobbie.

The bloke said any attempt to continuously feed it will burn the coil out..

OK, 555 may be overkill, could probably do it by dumping a charged capacitor
into it using transistors to pump the charge through it.

I think this may be how the company use it - he mentioned using a 6.8mF
capacitor.

Simplest way is to dump a big cap into them via a relay. Exact
capacitance will depend on the mechanics, I cant really remember what
I used for another solenoid + small load app, it was long ago. But I
do remember it never missed a beat, which I wasnt sure about when I
designed it.


Anyway, with these valves, you bang a charge pulse through them one way to
turn on and the same charge through the opposite way to turn off. Do
nothing and they maintain their current state.

Me - it'd probably use a little 14 pin AVR microcontroller and as few
transistors as possible. They're like a quid, I'm setup to program them, I
can add a few failsafes (like if "call for water" is held high,
periodically send a refresher pulse to the valve every 10 minutes, just in
case it got stuck the first time (don't know if that ever happens), make
the valve "network" addressable too - RS485 being an easy choice) and any
other random funky stuff - probably all for a fiver, a bit of veroboard and
a little box all running off the 12V SELV supply that I need for other
things anyway.

Probably take a day or two to bang up a prototype that works.
And energy efficient to boot.

A whole day is a significant cost. The relay cap arrangement may be
primitive but its very quick and I had no failures. For best result
use a 2 pole relay and parallel the contacts, and of course check the
relay life ratings before purchase. The solenoid coil itself will act
to limit peak i, so no contact side suppression needed.

BTW this method works fine on voltages significantly above coil
rating.


The only thing lacking is positive feedback that the valve is open or
closed,which is something you can of course have with a motorised zone
valve (mains operated at more cost too).
Cheers

Tim

[NT[_2_]]

On Jun 22, 9:39*pm, Tim S wrote:
Jules coughed up some electrons that declared:
On Mon, 22 Jun 2009 09:54:21 +0100, Tim S wrote:

Just had a call back from the designer (who I guess is also the owner)..
Very interesting... They use a custom design latching solenoid valve,
driveable by pulse in the range of 6-24v. And he seems happy to sell the
valves on their own.

Nifty. It's probably worth checking what testing's been done in terms of
estimating the number of cycles it'll stand before failing, as that'll
dictate what applications it can be used for.

This is a good point.

Like a PIR in the bathroom to operate the extract fan, but at teh sam
etime cut off the water to prevent flooding.

Stuff like that makes me nervous in case the valve fails - it doesn't look
like it has any feedback as to current state, so you really need extra
gubbins 'downstream' to check that the valve has actually done what
you've asked it to.

Indeed. Regarding the "flood prevention" - my view is that it doesn't make
the situation any worse than not having a valve (unless the valve itself
suffers catastrophic failure and ****es water everywhere - which hopefully
is a very unlikely scenario compared to "fails to control the water" mode
of failure[1]). So it's a net win.

[1] I'm expecting to see something loosely based on a washing machine valve
design with a clever drive mechanism - but I might be wrong.

However the lack of positive feedback is a pain, especially for diagnosing
problems - lack of control on a radiator (my main intended application)
will result in the room beiong either too hot or too cold.

I was thinking about this in the car this evening... The obvious solution is
to put a flow switch in.

This however is expensive and also prone to fail being a mechanical part.

So, I thought - seeing as I'm going to whack an AVR microcontroller next to
the valve, why not stick a temperature sensor on the output pipe next to
the valve? Could be a Dallas 1-wire jobbie (I like them and have driven
them from AVRs with excellent success) - or even a thermistor and use the
AVR's A/D converter.

In any case, one would expect 2 things of the temperature on a pipe:

a) When valve is closed, output pipe temperature should tend towards room
temperature over time, where I might expect a time constant of minutes;

b) When open *and* downstream is accepting flow (always with a rad,
intermittently with taps/shower/etc) then the pipe temperature is either
going to hit perhaps 10C or less (mains cold) or 50C+ (hot water). These
are pretty extreme temparture changes to be looking for and I think should
give *a reliable indication of the radiator valve working. For flood
prevention, one should expect a reliable indication that there is no flood,
but one will never be sure *all the time* if the valve is opening
correctly, but you will get indications *some of the time* (tap on) so
could do long term analysis and flag up a failed valve.

SMWBO taking a cheesegrater to my nuts after the shower lost hot water of
course is the 100% reliable indicator the valve died(!)

I'll ask the bloke if I can buy one for a sample and test it...

Cheers

Tim

lol, maybe thats where you should put the thermistor

Thermistors are very simple. A more basic option is to repeat the
drive pulse a bit later, which is trivial in software. A mechanical
flow meter is just one more relatively vulnerable failure point.

And ultimately some failures are easier to let happen than get into
complex solutions, depending on your app and control method.

And of course sometimes software can deduce failures from system
behaviour.


NT

[Dave Liquorice[_2_]]

On Mon, 22 Jun 2009 21:39:48 +0100, Tim S wrote:

However the lack of positive feedback is a pain, especially for
diagnosing problems
snip - complex things with temp sensors or flow switches

Something must move when the valve opens and closes. Get one and see
if you can position the arm of a microswitch in a suitable place or
attach a linkage to operate a microswitch.

--
Cheers
Dave.

[Tim S]

Jules coughed up some electrons that declared:

On Mon, 22 Jun 2009 09:54:21 +0100, Tim S wrote:
Just had a call back from the designer (who I guess is also the owner).
Very interesting... They use a custom design latching solenoid valve,
driveable by pulse in the range of 6-24v. And he seems happy to sell the
valves on their own.

Nifty. It's probably worth checking what testing's been done in terms of
estimating the number of cycles it'll stand before failing, as that'll
dictate what applications it can be used for.


Apparently, 200,000 operating cycles as required to get WRAS certification,
so he said.

I've ordered a sample of one to play with - I'll let you know what I think.

Cheers

Tim

[Jules[_2_]]

On Mon, 22 Jun 2009 23:31:06 +0100, Dave Liquorice wrote:

On Mon, 22 Jun 2009 21:39:48 +0100, Tim S wrote:

However the lack of positive feedback is a pain, especially for
diagnosing problems
snip - complex things with temp sensors or flow switches

Something must move when the valve opens and closes. Get one and see
if you can position the arm of a microswitch in a suitable place or
attach a linkage to operate a microswitch.

That was my thought, too - there must either be a sliding or rotating part
which acts as the actual valve, and this must have *something* going to
the outside of the valve body so that it can be driven by the solenoid
actuator mechanism.

Hopefully there's a spot where either a mechanical switch or some sort of
optical switch can be attached in order to sense the position of the valve
itself (regardless of whatever the drive mechanism is doing).

Of course the sense switch could also fail - but I suspect this doesn't
matter as it can still be detected as a fault condition and a real human
being can be alterted.

cheers

Jules

[Bob Minchin[_2_]]

Jules wrote:
On Mon, 22 Jun 2009 23:31:06 +0100, Dave Liquorice wrote:

On Mon, 22 Jun 2009 21:39:48 +0100, Tim S wrote:

However the lack of positive feedback is a pain, especially for
diagnosing problems
snip - complex things with temp sensors or flow switches

Something must move when the valve opens and closes. Get one and see
if you can position the arm of a microswitch in a suitable place or
attach a linkage to operate a microswitch.

That was my thought, too - there must either be a sliding or rotating part
which acts as the actual valve, and this must have *something* going to
the outside of the valve body so that it can be driven by the solenoid
actuator mechanism.

Hopefully there's a spot where either a mechanical switch or some sort of
optical switch can be attached in order to sense the position of the valve
itself (regardless of whatever the drive mechanism is doing).

Of course the sense switch could also fail - but I suspect this doesn't
matter as it can still be detected as a fault condition and a real human
being can be alterted.

cheers

Jules

Why should anything moving outside the valve body? Normal solenoid
valves don't; they use magnetic coupling to operate the valve.

Bob

[Jules[_2_]]

On Tue, 23 Jun 2009 16:44:53 +0100, Bob Minchin wrote:
Why should anything moving outside the valve body? Normal solenoid
valves don't; they use magnetic coupling to operate the valve.

.... and today I learnt something new :-)

Seriously, I didn't know that. Many years ago in early teens (I think
whilst futzing with solenoids in school science lessons) I remember
thinking 'wouldn't it be nice if valves were magnetically operated', but
I'd always assumed that a large enough field would just use too much
power to be sensible except for only a few applications.

cheers

Jules