raw water sensor/heat sensor for exhaust alarm

[colvic987]

I am looking for a raw water sensor or a heat sensor for exhaust alarm.

prefer a strap on to exhaust hose type and a sensor alarm

What is out there to buy as a kit.

 

[lenseman]

What sort of temperatures are you looking at as the temperature sensor/alarm can be easily custom designed and built to suit your requirements?

 

[colvic987]

all i know is that the thermostat is fully open at 74c, but dont know any of the high/low temp for exhaust elbow output and exhaust hose parameters. That is why i was looking on getting a kit, as all parameter stuff would be sorted already.

The engine is a md7a, do you know the parameters for it at exhaust elbow/exhaust hose limits.

 

[lenseman]

all i know is that the thermostat is fully open at 74c, but dont know any of the high/low temp for exhaust elbow output and exhaust hose parameters. That is why i was looking on getting a kit, as all parameter stuff would be sorted already.

The engine is a md7a, do you know the parameters for it at exhaust elbow/exhaust hose limits.

I am not sure I follow your reason for requiing a temperature kit? If the stat is fully open at 74°C, then I take it that it operates correctly and that you have measured the operating rang of the stat and that it is supposed to open at this temperature, which seems a little low?

Using a similar situation with diesel and petrol car engines, the thermostats run with pressurised (2 bar) systems and often open at temperatures closer to 100°C (the stats have the temperature marked on its base often they are 87°C or 92°C).

Can you be a bit more explicit with exactly why you need at temperature kit?

 

[colvic987]

I am looking for an alarm that will indicate that i have either no water going thru exhaust and the exhaust hose is starting to reach an overheating temperature, i know you can get alarms to strap on to the exhaust hose or elbow, or screw a sensor into the hose itself.
But i dont know which type to get and who makes them. Any one have advice on one they have fitted and was it easy to fit.
I also don't want to pay hundreds of pounds for one.

The thermostat measurement was taken from the engine manual, as thats all i have at the mo.

the boat has just been lifted out, and this is one of the winter maintenance projects.

 

[earlybird]

This could form the basis of an overheat alarm. Other temperatures are available. A buzzer and power supply would be needed as well.
uk.farnell.com/multicomp/t23a090asr2-20/thermal-switch-nc-90-c/dp/1006844?crosssellid=1006844&crosssell=true&in_merch=true&

Apologies, I've linked to a normally closed type of switch, which would complicate the alarm circuit. Farnell also do NO types.
Here's one
http://uk.farnell.com/honeywell-s-c/2455r-01000092/thermal-switch-no-65-c-80-c-reset/dp/1082204

 

[mattnj]

i have one of these:-

http://cpc.farnell.com/honeywell-s-...itch-n-0-60c-45c-reset/dp/SN36002?Ntt=sn36002

held on the exhaust elbow with a metal cable tie, then connect one end to earth, and the other is piggybacked onto the existing temperature sensor on the engine....(you need to check your existing engine overheat sensor works that way first) so it triggers the same alarm....very simple, very cheap, and it have the added benefit of tripping off generally when you turn the engine off (a bit of heat soak into the elbow) so it tests itself almost every time you restart the engine for the first say 20seconds...

couldnt be simpler and works a treat!

 

[pampas]

PBO did a flow alarm circuit no 474 June 2006

SN356000 flow switch
SC00990 12v red led
SR00143 100dB buzzer
CNO terminal block
?EW 211000R 100 ohmn 3watt resistor
? page torn

WWW.cpc.co.uk

Two sizes of flow switch to suit hoses best fitted I find to the exhuast injestion line.

 

[nimbusgb]

I've got a couple of the smaller flow switches knocking about and one of the larger ones if anyone is interested.

 

[rjp]

I bought one of these last year: http://www.trickettmarineproducts.co.uk/rawwater.html and it provides a neat though slightly expensive solution. The only problem I had fitting it was that I found it had American NPT threads and although the supplier said you could force an Imperial fitting into it I decided I didn't fancy the risk of a leak or cracking the plastic. I eventually found that you could buy NPT fittings from Aquafax.

I'm really pleased with it, not only would it warn me if my intake blocked or my impellor failed, it also reminds me to turn the key off after I stop the engine (which I was often forgetting to do). You can also select to wire it as a continuous or intermittent alarm. I've used the latter and with a regular 1 second beep of the very loud alarm I use it to time the engine preheat on my Perkins Perama - just count the beeps!

John

 

[pete]

I bought mine from here http://www.borelmfg.com/products_alarm.htm
around 4 years ago and have been very pleased with it.
I have also incorporated a flow switch in to the system as well.

pete

 

[Leighb]

I bought mine from here http://www.borelmfg.com/products_alarm.htm
around 4 years ago and have been very pleased with it.
I have also incorporated a flow switch in to the system as well.

pete

Can you advise which flow switch please? I am looking for a metal flow switch to go with a circuit posted here some time ago. The flow switch shown was all plastic and had a flap valve which would restrict water flow. I am hoping to find a metal one which is full bore.

 

[TNT]

over heat sensor

Hi, its your lucky day, take a look at PBO this month in the practical tips section, a guy has designed one out of simple components for less than £10.00 and it clamps to the exhaust elbow. Its self assembly but its only simple soldering and can be made to suit your own requirements.
Worth the cost of the magazine or you can log onto their web site.

 

[claudio]

Hi, its your lucky day, take a look at PBO this month in the practical tips section, a guy has designed one out of simple components for less than £10.00 and it clamps to the exhaust elbow. Its self assembly but its only simple soldering and can be made to suit your own requirements.
Worth the cost of the magazine or you can log onto their web site.

Can't get much simpler than this http://www.trickettmarineproducts.co.uk/scan0001[1].pdf

Website
http://www.trickettmarineproducts.co.uk/exhaustalarm.html

 

[TNT]

Temp Sensor

Sorry, by simple I meant easy to make for the cost of the components and probably a couple of hours max to make.
..............as always with sailing cost is the main driver.

 

[yerffoeg]

I agree with John that a raw water flow sensor may be a better option. I fitted one to my boat and I am very happy with it. As has been stated in previous threads on this subject, once a heat sensor sounds you are probably in deep trouble already.

 

[claudio]

I agree with John that a raw water flow sensor may be a better option. I fitted one to my boat and I am very happy with it. As has been stated in previous threads on this subject, once a heat sensor sounds you are probably in deep trouble already.

It's a bit horses for courses really you need both. If the flow sensor doesn't alarm out at idle speed (which it shouldn't) it will not detect a blockage that supplies the same volume of water whilst cruising. In this instance the temperature sensor will activate and warn you of the blockage.

 

[richardsnowstar]

I bought one of these on ebay;

http://cgi.ebay.co.uk/MARINE-EXHAUS...cessories_SM&hash=item19bcce6059#ht_500wt_721

it is pretty much the same as the PBO project but you get a neat panel for the warning lights and buzzer.

 

[Leighb]

It's a bit horses for courses really you need both. If the flow sensor doesn't alarm out at idle speed (which it shouldn't) it will not detect a blockage that supplies the same volume of water whilst cruising. In this instance the temperature sensor will activate and warn you of the blockage.

There is a good case for both I would think.

The water flow will alarm should you get a total blockage due to plastic bag/weed etc. In this case the impellor will have been wrecked before your exhaust alarm sounds.

However as claudio says above it may not go off when you have restricted flow possibly elsewhere in the system. In this instance the exhaust alarm would be better.