lpg solenoid

[kbs]

Hi,

Having an LPG car and seeing how cheap the LPG solenoids are....

I would like to add a shut off solenoid to a gas bottle suppling (just) a cooker on a boat.

This would be immediately after the butane regulator on the (6 or 8mm) flexible gas pipe.

The car type are in the liquid stage - I would need to use something in the gas stage. Would a liquid stage valve be appropriate?

The gas bottle would still be isolated by the mechanical valve on the bottle when left unattended but would be useful to have an additional electronic isolator that could be controlled from near the cooker.

The proposed position for the valve would be in the gas locker as this can safely drain away any minor leaks. Leaks that make it into boat have no way of draining away (unlike a caravan) so have to be avoided if you want the boat to remain afloat.

Thanks Kbs

[rossko]

They have a substantial electrical current draw, an amp or so. Clever types could make a peak-n-hold driver to reduce long term draw.

Valves for liquid LPG have to rated to handle gas too, as that would be found under normal 'empty tank' conditions. Valves without filter do exist and would be appropriate here. The through channel is small though, compared to pipework bore - you may be better off using an "8mm" type for 1/4" vapour tubing.

[Tubbs]

Or just turn the gas bottle off when you are out ? Unless it's because the cooker is leaking. In which case you should really change it. All boats should have a stop tap on everything separately anyway.

[mat_fenwick]

This is in fact what I've done on my campervan - I have a vapour take-off tank underneath which is a pain to isolate with the tap (have to get down on my hands and knees, undo the cover etc.) As I had a spare liquid solenoid kicking around I just used that. It is installed in 8 mm pipe and runs a two burner hob, smaller heater and fridge, with no evident problems.

Whilst the coil is rated for 12 V operation, I've found that mine will operate reliably down to 4.5 V, which drops the current down to a liveable with 140 mA. As an aside I've wired it to cut the gas with the engine running (triggered by the voltage sensing relay for the leisure batteries) to avoid the possibility of driving off (and potentially pulling into a petrol station ) with the fridge still running on gas...

[LPGC]

I agree with others that a manual valve would be a better option but I suppose that comes down to specific application (we know it's for the boat cooker) and personal preference. Personal preference isn't a term I use very often, I maybe use it here because as a kid I once flattened the starter battery on dad's boat while out at see by connecting a spotlight to see better into a storage compartment and leaving it turned on all day! Was very happy we had an auxiliary battery to start the engine but was always a little dubious about even the ship to shore radio and echo sounder being left on when out at see after then

What is there in terms of manual valves? Inline and floor mount gas taps, both obviously rated for low pressure propane and made for purpose, at least used to be available from caravan suppliers, the floor mount type being standard fit on old caravans etc. I just looked at GasIt and TinleyTech and didn't see any, so surprised they didn't stock a manual valve I looked a bit further to see if anything like it was available and found this, looks suitable but is relatively expensive: http://www.force4.co.uk/4517/Force-4-Au ... Valve.html

I nearly didn't write this because I don't want to put ideas in anyone's head who may be reading this... Don't use a petrol shut-off solenoid with manual override, not sure but maybe the internals would turn into mush when exposed to LPG, not good

Simon
www.Lpgc.co.uk

[kbs]

Thank you everyone for your advice.

The reason for not having a conventional mechanical shut off valve is that there already is one on the bottle. This is operated when ever we remember.

Whilst adding one inside the boat would prevent the cooker accidentally being left on (or leaking if it developed a fault), it will not protect me from the valve itself (or hosing feeding it) failing.

Whilst no gas leak is good, if I mount an electric solenoid in the gas locker - any leak caused by the valve failing will drain overboard rather than into the (nearly water tight) boat.

Its laziness thats driving this, on a wet and cold night in a glorious UK marina - no one wants to go outside to the gas locker to shut the valve. We all know we should but there have been occasions when its been forgotten.

Its the same at sea, in traditional British weather - the gas locker and valve are not easy when bouncing through waves trying to keep your breakfast down.

So I'll look for a good value solenoid valve - if it has a filter then I'll remove it. I'll try running it on a bench supply and see what voltage it opens at. Like the idea of using a 5V reg next to the solenoid as (in my experience) such regs are better protection than a fuse alone. Just need a gas tight seal to pass the cabling through to the gas locker.

Thanks again guys - I would not of thought of running it below 12V.

[mat_fenwick]

If you're thinking of running it from something like a 7805 regulator, that won't be the most efficient as it merely dissipates the excess voltage as heat. I was going to build a circuit around a LM317T chip, using it for a switching power supply - then I realised I had several such circuits already in the form of plug-in cigarette lighter adaptors with 3/4.5/6/9 volt outputs!

It will hold open with only 3 V @ 70 mA, but won't actually open with such a low voltage. I do have the option to drop the current if we'll be stopped for a while, but in practice this hasn't been needed.

[kbs]

Thanks Mat,

Power consumption isn't a big issue, the engine is run most days and gas is only required for short periods.

Reason for the 5v reg is the neat inbuilt overheat/over current shut down. Might be a job for a 317 in current mode?

Intending to use via a 1hour timer (ptm - run for one hour - shuts itself off). Nice big bright LED showing when it is on.

Snubber diode (unless included in coil) & fuse - ready to go.

[LPGC]

If you're thinking of running it from something like a 7805 regulator, that won't be the most efficient as it merely dissipates the excess voltage as heat. I was going to build a circuit around a LM317T chip, using it for a switching power supply - then I realised I had several such circuits already in the form of plug-in cigarette lighter adaptors with 3/4.5/6/9 volt outputs!

It will hold open with only 3 V @ 70 mA, but won't actually open with such a low voltage. I do have the option to drop the current if we'll be stopped for a while, but in practice this hasn't been needed.

I very nearly included a bit about voltage regulators effectively just converting the excess voltage into heat (thus not lowering draw from battery) myself but then thought I'll leave that point alone for now because as a concept lowering the voltage isn't a bad idea, might just need to be done in a different way - If he wired say a few similar solenoid coils in series with the working coil then the current draw will be lowered. 12v into a 16ohm coil draws 750mA, if the solenoid holds at 3v then since 3v is a quarter of the 12v another 3 similar coils could be wired in series to divide the voltage to 3v across the coil. 4 Coils would total 64 ohms = 190mA battery draw at 12v (assuming the usual 16ohm coils, you did point out in your example that your coil drew only 70mA at 3v so your coil resistance must be higher?). Another thing that could be done, maybe not a great idea though...(!) The solenoid is designed to shut off a high pressure liquid gas feed, so maybe fitting a softer spring would allow the hold current to be reduced further whilst still effectively cutting off the low pressure vapour feed - Maybe leaving a nagging doubt over reliability though?

Simon
www.Lpgc.co.uk

Simon
www.Lpgc.co.uk

[mat_fenwick]

Just for clarification, as the OP isn't that worried about current consumption (whereas mine could be running a fridge constantly), the 70 mA was the current drawn in the 12 V side of the circuit. I didn't measure the actual current through the solenoid, just wanted to know the battery drain. The solenoid is a BRC blue top, and I think I measured it at just under an amp consumption at a nominal 12 V.

[rossko]

If you want to be a bit cleverer, build a 555 style astable with transistor output to drive the coil. Run a simple square wave output at say 500Hz driving the full 12V, experiment with mark/space ratio and freq. I expect a 10% on-time will be plenty to initially snap open the valve, repeat rate enough to hold it against spring closure without buzzing, while the 90% off-time will conserve current.

[kbs]

Wow, a lot of great ideas!

Would rather avoid driving via a 555 (or full blown switch mode) - noise is an issue to the instruments and I would need to run the cabling close to several of them.

I have previously improvised peak and hold circuits using a current limiting IC (again wasting energy as heat) with an electrolitic across the output. Post electrolitic is the relay needed to switch the coil. Providing the reg is powered up before the relay is thrown - you get a nice high current burst to open the solenoid then just the hold current via the analog current limiter and no real noise. A low value resistor is required to prevent the electrolitic overloading the reg and a couple of low val ceramics as per the regs data sheet to keep it all quiet.

My real reason for liking the regulator approach is the built in overheat shut down features as these give me extra confidence. Also I have had two Valtek coils failing on my car, as they fail they draw much higher current and get very hot. Once failed they are not a problem but fed on thin wiring (as they are) even the cabling gets worryingly hot whilst trying to pass enough current to blow the 10A fuse. I may use my DIY 'peak and hold' circuit so I can be aware of the problem before the wiring cooks.

If power consumtion was a concern then I would consider a quality switch mode supply - cheap ones are horrible - several occasions of 'guests' bringing mobile phone chargers that obliterate the VHF and dent the GPS signal - even though the transciever and GPS have decent filtering.

If this was a serious boat, we would be concerned about energy consumption but as the engine is run most days and Laptops are used......

Thanks again for all your help.

[LPGC]

Wow, a lot of great ideas!

Would rather avoid driving via a 555 (or full blown switch mode) - noise is an issue to the instruments and I would need to run the cabling close to several of them.

I did wonder about interference but thought there'd been 'nuff said, many of us seem to be into electronics here

Maybe it's a bit harsh of me but I still smile when I remember the old radio ham tale about the person who did themselves some harm when, after drinking, their ironing board started talking to them because the guy over the road was transmitting powerfully on ssb...

Simon
www.Lpgc.co.uk

[Gilbertd]

I'm an engineer for Ofcom (nee, BT, DTI, Radiocommunications Agency) so get called out to deal with the interference problems. I once got called out to one job where a little old lady was complaining that she could hear voices from her gas fire. Having read through the complaint and declaring her a nutter, I went to have a look anyway. Two doors down was a ham and, as it was a few years ago, he was running AM on 2m VHF. Got to the house and she insisted it was happening at the time. Went in a sure enough, there was a perfectly clear voice coming from the gas fire. It was one of the old style ones that has a chromed parabolic reflector with a central mantle. At some time the brass fitting to the copper pipe had got wet so had a nice layer of green on it. This had formed a diode so she had a crystal set with a length of copper pipe that was an almost exact quarter wavelength at 145 MHz. Cleaned the green off with a bit of vinegar and the voices went away......

Damn hams, more trouble than they are worth!

[Tubbs]

That's made me chuckle.

[LPGC]

Funny story Gilbert - Wonder if the lady considered her own sanity

I've only recently learned of some people's other interests being similar to my own so I wonder what other interests people have besides LPG. I was never a proper ham but years ago in my teens was known for modifying American CB's that featured SB to increase frequency range etc.. I know a few hams who now only use UHF to connect to local relay stations, they boast of talking to people all over the world via the relays... I've pointed out to them that we can all do the same using mobile phones these days and that relay stations seem a bit contrary to the point of being into radio but not much chance of interference at least. Hmm, I wonder how the skip and ionisation are doing, whether to fit my old full wave 30 footer on the house and/or fit the K40 on the car roof, see if people in the US and Italy I knew still get on the air Just kidding Gilbert

Simon
www.Lpgc.co.uk

[kbs]

Funny story Gilbert - Wonder if the lady considered her own sanity

I was never a proper ham but years ago in my teens was known for modifying American CB's that featured SB to increase frequency range etc..

Would that be attaching small caps to the crystals in order to transmit on the RC frequencies? Or bigger stuff to hop on to 10m? I remember looking up call signs from the other end of the country and using those with a modified CB from hilltops - didn't appreciate the importance of the time of day back then.

These days ham stuff is almost deregulated - no need to understand ohms law to get the basic licence which allows you most frequencies (max 10w). Still need to do a little bit of work to get the 400w licence.

Interesting what you were saying about hams using vhf/uhf via repeaters. Some lift conditions early this year where a local VHF repeator was reaching 100's miles when it normally covers about 40. Lots of guys very close to the repeater were shouting each other down in order to 'work' the distant station through it. Odd thing was, when the lift cleared, the repeator keeper moaned about the distant station hogging the air! No moans about the locals and the distant guy was being called, he was not the one doing the calling.

I only came across this after buying one of these £30 handhelds covering an unbeleiveable frequency range - any one intersted in radio who hasn't looked for a while - please see
http://www.ebay.co.uk/itm/New-Version-B ... 3cd71b473c

[Gilbertd]

Oh no, not the dreaded Baofeng!! We were all supplied with a Yaesu VX-5 a few years ago. Absolutely beautiful little piece of kit. Covers the 70, 145 and 430 MHz bands (or 4m, 2m and 70cms for any closet hams reading) with continuous receive from 50 to 500 MHz (and, if you know how to do it, can be made to transmit over that range too). Over the years a number of these have been lost, broken or died so last year a cheap and cheerful replacement was supplied, a Baofeng. Now, they aren't ever intended for serious work, just as a handy thing to stick in your pocket when you need to and cheap enough to not have to be put on the asset register so are regarded as disposable. But they are Rubbish! The front end is barn door wide so you'll hear things at least two channels either side of where you think they are and if you transmit for more than a couple of minutes so it gets hot, the frequency decides to drift up the band. Thankfully, I've still got my VX-5 so don't ever have to use the horrible little thing. As well as that, I've got a van parked outside with equipment installed in it that is worth about 4 times the value of the van (even secondhand, the Rohde & Swartz EB200 receiver in my van would cost you over £10k) and I'll use that any day!

I wasn't aware until recently that you can't do a proper exam and go straight to a full amateur licence these days, you had to go through the ladder climbing route. The original idea was to try to encourage schoolkids into radio. Lets face it, everything uses radio these days and the trade are crying out for people but there are very few that even have an understanding of what it is. It was envisaged that schools could run the Novice courses to help supply the demands of the mobile network operators, but it didn't happen.

And yes, i have a licence myself...... Whenever I am asked if I am an amateur, which is usually every time I have any dealings with one, I will reply that I hold a licence. I've held what used to be called a Class B licence (with a G8 call) since 1979 and, because of that I was accepted onto the BT Radio Interference Service in 1983. Since then, when I'm working with radio during the day, the last thing I want to do in the evenings is play with radio. That's what other things are for (it used to be women, then computers and these days it's a bit of electronics, motorcycles, Range Rovers and LPG). In fact, 3 years ago I moved house and now have a 100m long back garden. I thought about putting a wire antenna up so I could try HF (as my Class B has now become a full licence since they did away with the Morse requirement) but very quickly realised that would be as far as it went. Try it for a couple of hours and then not bother again.

However Simon, a word of advice. I know the man that covers your area and he's never got over the fun we all used to have in knocking off illegal CB'ers in the old days (2 or 3 sidebanders a night was quite common). I'm sure he'd be round like a shot if 30 feet of aluminium appeared on your house. Mind you, you'd probably put it up properly with clamps and brackets not chewing gum, wet string and the odd Jubilee clip like the CB'ers always used to do so he might mistake you for an impoverished ham.

Now this must be a first. It's not uncommon for threads to get a bit off topic, but LPG solenoids to cheap 'n' nasty Chinese radios in only 2 pages must be some sort of a record!

[LPGC]

Funny story Gilbert - Wonder if the lady considered her own sanity

I was never a proper ham but years ago in my teens was known for modifying American CB's that featured SB to increase frequency range etc..

Would that be attaching small caps to the crystals in order to transmit on the RC frequencies? Or bigger stuff to hop on to 10m? I remember looking up call signs from the other end of the country and using those with a modified CB from hilltops - didn't appreciate the importance of the time of day back then.

From memory (27 years ago!) small caps maybe in some cases but usually bigger mods like a full extra crystal board (with different crystals), switch and circuity to select the crystals on the second board, usually different ferrite rods or at least a bit of screwing in/out in their coils to get the rig to stretch to the new frequencies, sometimes different coils if that still failed to get the frequency range required. Some were more successfully converted than others of the exact same model... You couldn't get every rig to go 'super low' or 'super high' (frequencies) and rigs that would go to both extremes were rare - so you could only say 'I'll try to get the frequency range you want but is super high or super low most important to you?'. The holy grail was a rig that would go super super low to super super high Also used to modify with switchable 'roger beeps' and wider kc shift to effectively reach any frequency in the band (except for missing frequencies due to channel spacing in each range of 40 channels - or was that the legal FM stuff ). Cybernet boards usually, the Unidem boards were more respected for selectivity but harder to mod, with Cybernet USB/LSB always sounded like people were on helium no matter what you did with the clarifier. I modded one Cybernet by connecting it to the user port on a BBC computer to switch the PLL inputs and bands, the computer then switched channels and monitored signal strength on each channel via the A/D games port so I could see which channels were active etc. The internet, mobile phones and 80 channel legal stuff pretty much killed off the illegal CB and very illegal sideband scene. Still may have a HighGain 5 and Stalker 9 somewhere gathering dust but was only kidding about getting into it again Gilbert!

Simon

[kbs]

Hi Simon,

Ah, I never got as far as that. Small caps were used to lift us just out of legal band. We would do the same to enter the 'gaps' in the old US channels (RC frequincies?). None of the other School kids had communications receivers - just basic CBs therefore we could have almost private (as in no other Kids listening) chats using very low power to avoid attracting the attention of the gray beards.

Hi Gilb,
You’ve missed the important faults of the UV5R – leaking RF from rear exposed battery terminal and low TX audio. Not sure which BeoFeng you tried – but the UV5-R is reasonably selective – easily out performs my IC-R20 @70cm. There are a few reports of adjacent channel problems but I suspect this is in narrow band setting. The manual tells you the RX is always wide band regardless of software settings (they don’t explain why but the £20 - £30 price tag could be a clue).
A big part of the ‘fun’ is discovering which settings in the software do what – often not quite what is says in the menu or manual.
Thanks for the suggestion of the £10 Chinese fuel pump in the other thread , thinking of asking if they can bundle some beoFeng stuff with it to save me on postage.
Cross threading from LPG solenoids to Chinese Radios to Chinese Fuel pumps? Def off-topic.
Thanks for all the great info/stories everyone – had fun reading.

Keith