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Gas detector problem
The gas detector we use from gas detector Sieger 780 for natural gas. Problem is some gas detection module which is from control equipment, UK show gas even though there is no gas.

I work in a fire & gas detection system of a power plant which is from Control Equipment, UK. The gas detector we use from gas detector Sieger 780 for natural gas.

Problem is some gas detection module which is from control equipment, UK show gas even though there is no gas. We check gas detector and find gas detector ok. The problem appearing repeatedly and my work value is going down.

Could anyone explain where is the problem?
Also how we can simulate a sieger 780 gas detector?

Depends what type of Gas detector you are using? Some gas detectors will appear to show gas level if the optics are dirty so you should give it a good clean. If the gas head is not one that can be cleaned then change the 780 card out for a known good one as it's not unheard of for these to fault. If the problem is still in the original circuit, you may need to recalibrate the card. Really depends on the type of detector you have though. How did you 'check' the gas detector? I presume its a 4-20mA device, check this signal into the card? If it's anything other than 4 - 4.5mA then change the gas head.

mat.bones@gmail.com

By Fred Graham on 7 March, 2005 - 5:37 pm

I am not familiar with Sieger, but there are a number of different techniques in gas detection. Some methods are subject to gas cross sensitivities. For example an NF3 electro-chem sensor is cross sensitive to flourocarbons due to the similar chemical compositions. You might check
with Sieger to see if they are cross sensitive to other compounds. Your equipment may be working just fine and it is just picking up other compounds.

let us have the contact details for getting sieger spares. I was unable to trace the sieger through the web.
can u guide me to their site.

sajeesh

Hi there!

I have experience on this issue.

The problem possibly comes from bad connection of the wiring. Try to check all the connection points.

Also to do the calibration carefully. The atmosphere around the sensor head must be fresh air during zero adjust.

By Tibor Cseszko on 20 March, 2008 - 10:47 pm

Check the 4-20mA output from sensor. If there is nothing registering then put span gas on sensor to "jack it up". If your 4-20mA shows gas, then your sensor is good. After that, ZERO card and calibrate sensor through controller. If that does not work, your controller is bad.