tome
Well-Known Member
Ongolo
If you like, I could put the drawings on my site with a link. I'll PM you my email address.
Cheers
Tom
If you like, I could put the drawings on my site with a link. I'll PM you my email address.
Cheers
Tom
Gas Alarm - worth it?
- Thread starter CharlesM
- Start date
CharlesM
Well-Known Member
Ongolo
PM'd you
2 weeks you are off the net? Are you going cruising then?
Charles
PM'd you
2 weeks you are off the net? Are you going cruising then?
Charles
meddite
Well-Known Member
I wouldn't bother. Our boat was commissioned in 1998 and a Pilot single station alarm fitted by the UK distributor as an optional extra. The sensor was fitted under the cooker, below the sole. The alarm went off within a week, and intermittently thereafter. Not good news, particularly at night!
Our commissioning electronics expert tried testing the system with a mini smoke generator, and other gismos but was unable to find a fault. All he could do was disconnect it. Not surprisingly, it disappeared from the distributors options list a year later, we assumed because of this being a general fault.
We wondered if the "fumes" from GRP resins in the new hull had been setting it off, but 10,000 miles later, and after several re-connection attempts between Hamble and Porto di Roma, "Ghastly Gordon the Gas Alarm" has had the snip and been permanently silenced.
Our commissioning electronics expert tried testing the system with a mini smoke generator, and other gismos but was unable to find a fault. All he could do was disconnect it. Not surprisingly, it disappeared from the distributors options list a year later, we assumed because of this being a general fault.
We wondered if the "fumes" from GRP resins in the new hull had been setting it off, but 10,000 miles later, and after several re-connection attempts between Hamble and Porto di Roma, "Ghastly Gordon the Gas Alarm" has had the snip and been permanently silenced.
charles_reed
Well-Known Member
The truth is
a) they were too pissed
b) they knew you were the most mechanically competent
c) they were engaged in an all-absorbing discussion
also
it's a long time ago since women established they were as good as men (if not better) and it's no good whinging if they treat you thus.
I know Germaine Greer is busy trying to put the clock back, having seen the error of her views....
a) they were too pissed
b) they knew you were the most mechanically competent
c) they were engaged in an all-absorbing discussion
also
it's a long time ago since women established they were as good as men (if not better) and it's no good whinging if they treat you thus.
I know Germaine Greer is busy trying to put the clock back, having seen the error of her views....
chops_uk
New Member
As long as it's not to the detriment of good practice and sensible manual checks I'd rather be woken up at 3am a few times because someone 'floated an air biscuit' or sprayed deodorant than having a 'Lord Trenchard' happen because of a miniscule leak somewhere.
my better half's an engineer and mentioned that she considers them unreliable and also mentioned the increased danger of people placing undue reliance on them (i believe that she now also does risk assessments on this sort of thing)...
..It's just crossed my mind reading this, that the gas alarm which regularly went off when the engine ran (on a boat i used to crew on), probably warranted more investigation into the exhaust system..
my better half's an engineer and mentioned that she considers them unreliable and also mentioned the increased danger of people placing undue reliance on them (i believe that she now also does risk assessments on this sort of thing)...
..It's just crossed my mind reading this, that the gas alarm which regularly went off when the engine ran (on a boat i used to crew on), probably warranted more investigation into the exhaust system..
Phoenix of Hamble
Well-Known Member
All interesting stuff.... general tone seems to be in favour of fitting...
However, nobody addressed the second question of how they are wired in?....
I've always been told that they need to be permantly wired in, as:
a] gas can leak at any time! (although as we all know, we should switch off the gas at the bottle when not on the boat)
b] the act of switching it on is dangerous if a gas leak has ocurred!
However if its using 2.5Ah petr day then we need a charging system I guess.... or do we work on the theory of gas alarm first, then gas when we get to the boat?
Comments?
However, nobody addressed the second question of how they are wired in?....
I've always been told that they need to be permantly wired in, as:
a] gas can leak at any time! (although as we all know, we should switch off the gas at the bottle when not on the boat)
b] the act of switching it on is dangerous if a gas leak has ocurred!
However if its using 2.5Ah petr day then we need a charging system I guess.... or do we work on the theory of gas alarm first, then gas when we get to the boat?
Comments?
ongolo
Well-Known Member
The only sensors I have come across in Conrad and RS components are a zinc something combination that is heated by a little heating element that use 5V 100mA, then when a gas is present, these sensors change resistance and thus current drastically. It is not neccessary to have the treshold of the amplifier set too critical. I made mine so, that if I open a can of petrol half a meter away from the sensor, the alarm goes off. It is easy to adjust, possibly the designer set the gain of the amplifier too high in the hope to make the device more sensitive, but the resistance changes with a gas present are rather drastic. I will post the designs on the website offered, but only friday onwards. Or the designer tried to cut down on the heating current to save battery life. The heating current must be constant or the sensitivity or treshold of the trigger will change. So no short cuts on consumption possible if you like reliability
regards ongolo
regards ongolo
ongolo
Well-Known Member
connect the alarm to 12 volt plus four wires going to the sensor, two wires for the heating coil, and two for the resistance changes. That is it.
regards ongolo
regards ongolo
Ships_Cat
Well-Known Member
the second question of how they are wired in?.... - and the blowing yourself up with it bit.
Ours is a Canadian one (forget the name) which is permanently wired in, and runs continually except when we leave the boat for a day or more (when we isolate all electrical). We are always on board for a couple of days a week and also spend 6-8 weeks cruising each year. Has been going over 8 years and still working ok (including near a year liveaboard).
Sensor is located in the bilge, a little in front of and below the engine at about mount level (there is a floor in between though), the electronics box mounts remotely (in the galley) and also controls a solenoid valve at the cylinders. There is a sensitivity adjustment in the box and we don't get false alrms unless from an obvious cause eg using hydrocarbon propellent spray cans in the boat.
Have also heard it said that if you turn them on when the bilge is full of gas you are likely to blow yourself up. Cannot see that, at least with ours, as the sensor only gets warm. Haven't really checked but it seems to have a warm up cycle of around 10-15 seconds before it initiates itself.
John
Ours is a Canadian one (forget the name) which is permanently wired in, and runs continually except when we leave the boat for a day or more (when we isolate all electrical). We are always on board for a couple of days a week and also spend 6-8 weeks cruising each year. Has been going over 8 years and still working ok (including near a year liveaboard).
Sensor is located in the bilge, a little in front of and below the engine at about mount level (there is a floor in between though), the electronics box mounts remotely (in the galley) and also controls a solenoid valve at the cylinders. There is a sensitivity adjustment in the box and we don't get false alrms unless from an obvious cause eg using hydrocarbon propellent spray cans in the boat.
Have also heard it said that if you turn them on when the bilge is full of gas you are likely to blow yourself up. Cannot see that, at least with ours, as the sensor only gets warm. Haven't really checked but it seems to have a warm up cycle of around 10-15 seconds before it initiates itself.
John
jerryat
Well-Known Member
Hi Tome!!
Got back home earlier than expected and have searched through everything boaty in the house (and that 's a hell of a lot!) but couldn't find the adjustable sensor receipt. However, I did find the company from whom I bought the original gas alarm system, and I'm virtually certain they also supplied the adjustable sensor so do try:
KM Electronics
25 Melrose Close
Lowestoft
Suffolk NR32 4QJ
Tel: 01502 569906
Mob: 0831 865277
As I mentioned earlier, I bought the thing a few years ago and don't know if this company even exists anymore, but it's the best I can do I'm afraid.
Hope it helps
Cheers Jerry
Got back home earlier than expected and have searched through everything boaty in the house (and that 's a hell of a lot!) but couldn't find the adjustable sensor receipt. However, I did find the company from whom I bought the original gas alarm system, and I'm virtually certain they also supplied the adjustable sensor so do try:
KM Electronics
25 Melrose Close
Lowestoft
Suffolk NR32 4QJ
Tel: 01502 569906
Mob: 0831 865277
As I mentioned earlier, I bought the thing a few years ago and don't know if this company even exists anymore, but it's the best I can do I'm afraid.
Hope it helps
Cheers Jerry
jerryat
Well-Known Member
Re: KM Electronics is Yachtbits...
Hi pvb,
Thanks for that!! Hopefully they'll be able to help Tom out with the sensor.
Cheers Jerry
Hi pvb,
Thanks for that!! Hopefully they'll be able to help Tom out with the sensor.
Cheers Jerry
tome
Well-Known Member
Re: KM Electronics is Yachtbits...
I couldn't find any gas sensors on the site, but will keep trying. Thanks anyway!
I couldn't find any gas sensors on the site, but will keep trying. Thanks anyway!
pvb
Well-Known Member
They used to make the \"Canary\" gas detector...
They used to make the "Canary" gas detector system, but I don't think they still offer it.
They used to make the "Canary" gas detector system, but I don't think they still offer it.
ongolo
Well-Known Member
Hi Charles, not yet cruising, but lying at mooring 5 miles from the nearest phone, near 5000 seals and about a 100 regular heaviside dolphines, with the occasional visit of some bottle nose.
regards ongolo
regards ongolo
jerryat
Well-Known Member
Re: They used to make the \"Canary\" gas detector...
Hi pvb,
Yes, it's the Canary system I've got and it's very good too. Tom, I'm not really surprised the sensor isn't shown on the website (would be difficult to show everything I suppose) but it may be worth ringing them to check if they've still any sensors in stock or, more importantly perhaps, put you in touch with their suppliers.
I hope you manage to sort something out anyway.
regards Jerry
Hi pvb,
Yes, it's the Canary system I've got and it's very good too. Tom, I'm not really surprised the sensor isn't shown on the website (would be difficult to show everything I suppose) but it may be worth ringing them to check if they've still any sensors in stock or, more importantly perhaps, put you in touch with their suppliers.
I hope you manage to sort something out anyway.
regards Jerry
30boat
N/A
I have a brand new plastimo gas alarm that was never installed because I went for a Wallas Parafin cooker wich obviously doesn't need one.It's yours cheap if you want it.