MSA detector

[vinaydeep]

In our facility we use MSA orion multigas detector. The literature of the detector does not tell anything about bump test. There is what is called auto calibration

We never do bump test
What is a bump test and the difference between bump test and calibration?

Secondly, if a %LEL sensor is defective ;will the detector give a alarm or will it only indicate zero in a clean atmosphere
any person with experience with MSA Orion can shed some light

Thanks

Vinay

[Richardl]

Hi,
MSA seems to call the bump test a "calibration check", and their procedure reflects the best practice short of an electronic docking station.
Flowing calibration gas across, the display should be very close (+/- 10% is typical for all but O2) to what the cylinder contains. If the readings are too far off, it's time to calibrate.
An LEL sensor that is failing could do either. As the sensor "ages", the readings will tend to become more inaccurate and may result in alarms. If the sensor has been affected by a sensor poison (refer to the instructions) the Orion could very well indicate 0 as the sensor may have stopped working altogether.

[JamesIdealCal]

Orion Info

Hey Vinay,

The functional bump test is basically a quick check before you go out in the field to make sure the sensors are functioning and alarms ready. On the Orion, it's pretty easy to do. I'm assuming you're using a pumped version, but if not it's very similar. Start the unit up, get everything into normal use mode. While it's starting, get your calibration gas bottle setup (put the regulator in, attach the hose, etc). Once everything is ready, and the gas detector is in normal use mode, attach the hose and let the gas flow for 5-10 seconds, then take the gas off. Watch your readings to make sure all the alarms hit and that the values you're seeing are fairly close to what you're seeing on the bottle.

For writing reports, saying +/- 10% is fine, but you're going to waste a ton of gas doing a 2 minute gas flow with calculated values, and if you institute a policy where it needs to be bumped before every use (using the 1-2 minute 10% method), people are going to pick it up and just not bump it because it takes too much time.

http://ohsonline.com/articles/2010/0...libration.aspx

The above is an article that describes the difference between a bump and a calibration, and I also really like this article: http://safetyequipment.org/userfiles...-2010-Mar4.pdf by the ISEA which gives a good description. (The ISEA are the people who OSHA take their "calibration guidelines" from)

Sorry for being long winded, but detector calibrations are really important to me.

As for your second question:

Richardl is exactly right, the sensor can do either. The getting stuck at zero is the most dangerous one for certain. The two biggest offenders are Armor-All and WD40, both of which will turn LEL sensors to instant paperweights. Basically anything which vaporizes and contains sulfides or silicon compounds are bad. LEL sensors have more of a tendency to fail down, which means they almost always err on the less sensitive side (at least in my experience). So watch your values during calibration and make sure you do those bump tests before you take it out for the day.

A quick check to make sure it goes into alarm will really make a difference and could potentially save a life, it only takes about 30 seconds overall.

If there are any other questions I can answer (I work with these things all day) let me know, my cell is 734-560-7481.

Best regards,

James Moore

[vinaydeep]

H2S detectors

Thanks James for the information.

I read your article as well it was great source of information.

I can therefore conclude that the ORION MSA brand need to be bump tested to check the sensors respond ?

auto calibration by the instrument itself by not passing any gas over the sensors is not a conclusive test method to prove the instrument functionality?


We also have H2S detectors MSA altair which have a 24 month display and decreases to zero. WHen the display hits zero what do we do?
Do these detectors also need bump test with H2S?

Thanking you very much for your information

Cheers!

[JamesIdealCal]

Sorry!

Hey Vinaydeep,

Sorry it took me so long to get back to you on this, somehow it fell under the radar for me and I didn't get an email.

"auto calibration by the instrument itself by not passing any gas over the sensors is not a conclusive test method to prove the instrument functionality?"

There's no device out there that can calibrate a gas detector without the actual gas. The "auto calibration" is really a way of saying "when you pass gas (I wish I could avoid the jokes at this point) over the instrument, instead of needing to turn little potentiometers with a screwdriver for each sensor one at a time, we'll have the software recognize the change in voltage and change the sensitivity automatically for you when you're in calibration mode" if that makes sense. It does not mean "automatically calibrating without any gas."

The H2S Altair single gas units also need to be bump checked daily. They might say "don't need to be calibrated" but it's patently false. They're using the same sensor technology as their other units. The only difference is that once you're done with the 24 months, you're out of warranty. If the battery dies or the sensor won't pass the bump check, it has to be thrown away.

Hope that helps! Sorry for taking so long!

James Moore
http://www.idealcalibrations.com/