Duomo gas detector panel

[Wangerman]

Hi guys

having a few problems with the above at our main boiler room

I have 3 Duomo gas analysers linked to a gas analysis panel and the trend bms

Recently two out of the 3 gas sensors have been showing a red gas warning light and shutting down the boiler interlocks thus we lose the boilers

I can always cure this by resetting the panel and the problem goes away for a few weeks

I am happy there are no leaks the incoming supply is 12" iron and all is well and I have had a tightness test performed

The boilers are Ideal 550 kw x 3 with Riello burners feeding 12 heating zones 2 hamworthy chlorifiers and running round a 18" iron coil (header?)

anyone got any ideas ?

I have had the trend checked over and all is ok there so maybe the sensors ????????

 

[Onetap]

I have had the trend checked over and all is ok there so maybe the sensors ????????

I think you'd need to get the gas alarm system inspected and re-calibrated by the manufacturers. It is a safety related device and it would be very inadvisable to allow anyone other than a specialist to confirm that it is working as intended. ISTR that combustible gas detectors have a limited life and have to be replaced when their life has expired.

How are the red lights operated?

Are the gas sensors wired directly into the Trend outstation (i.e., analogue inputs) and the Trend operates the lights, via a relay, when the sensor either goes above the alarm setting or goes out of limits (i.e., a defective sensor) ?

Or, are the sensors wired to a separate gas alarm panel with the red lights and there is merely a digital input from this to the Trend BMS outstation?

Is it possible that the system is working as intended and one of the boilers is leaking gas during the start-up cycle?

If so, is it possible to monitor the boiler operation (start-up or hi/lo fire) with the Trend system to see what the boilers are doing when the alarm is triggered?

PS I just looked up Duomo since I haven't seen them before. The manual says "This detector must be function checked as described above using calibrated test gas every 6 months. To arrange for a
Duomo engineer to conduct this work or to arrange a service contract....."

I think you're going to have to get them in to check it.

 

[Wangerman]

Thanks for your reply

The sensors are wired to a Duomo gas panel and then linked to the bms which I assume controls the interlock. The only other things which can hold the boilers off are the Grundfos twin head pumpset for the header and the Mikrofil.

This only seems to happen overnight so when I get there in the morning the boilers are stone cold. They go through their cycle as normal once reset and modulate from low to high fire fine on manual and auto.

The gas detection panel show a readout for all three detectors and have a green orange and red led to indicate the status of each sensor

Off memory the green indicates < 5% orange < 10% and honestly can't remember the red one

I am assuming this is PPM ?

sorry I am not a heating engineer and to be honest was not expecting much help on here with it as this is big boys stuff ( no offence).

Was wondering whether these sensors have a shelf life or maybe dust contamination can affect them they are about ten years old and have never given a problem until recently

You must be a clever guy thanks

 

[Wangerman]

Just read your post edit and to my knowledge they have never been checked

I will get the guys in to change them for new calibrate and then set up a service contract

thanks again you are a genius

 

[Onetap]

I looked up a Duomo gas sensor data sheet here;
http://www.duomo.co.uk/SGM595_Sensor.pdf

It says the engineer can plug in a data reader which will tell him, amongst other things, how many days of life the sensor has left.

I think they have a limited life, but the data sheet doesn't say how long that might be; presumably it depends on how much flammable gas they've been exposed to. You should be checking them every 6 months anyway. if they're 10 years old, I'd think they're knackered and replacement seems to be a specialist job.

1650kW? A small installation. 18" headers sound a bit OTT.

 

[Wangerman]

Sorry didn't mean to insult you it looks big and impressive to me didn't realise that kind of btu is small fry to some hope I didn't upset you

 

[Onetap]

hope I didn't upset you

Not in the slightest.

A long time ago I was involved in a lot of amendments in a plant room in that part of the world that had 3 boilers totalling 3,750 kW, I just looked up the details. The existing headers were 8". It was fun, mostly when it was finished.

 

[Wangerman]

It looked like a lot of fun to install I as there when it was all put together didn't look fun carrying cast iron boiler sections down the stairs though seems like my header is a little on the large size then

Still all works lovely most of the time so can't be too much wrong except the heating bills

Still preferred the old Allen ignis oil boilers though somehow they had a soul the shiny new boiler room doesn't

 

[Biggles..]

hope I didn't upset you

Not in the slightest.

A long time ago I was involved in a lot of amendments in a plant room in that part of the world that had 3 boilers totalling 3,750 kW, I just looked up the details. The existing headers were 8". It was fun, mostly when it was finished.

worst case id have the header for 1650Kw at 12inch.