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BudPiffo
Total Likes: 26 likes
| | | Re: gas detectors \ safety in mines < Reply # 9 on 1/18/2021 7:03 PM > | Reply with Quote
| | | No joke, you can fart on a H2S detector to test it if its an "eggy" fart. Not good for calibration but good for lols / checking the alarm works. For better calibration: Sodium sulfide (Na2S, NOT sulfate Na2S04) reacts with most acids to produce H2S. It's pretty available on the internet. You can make a volume of known H2S concentration: Let's assume H2S is an ideal gas; then 1 liter H2S = 0.0414 mole H2S 1 mole H2S <-> 1 mole Na2S + excess acid 0.0414 mole Na2S = 3.23 gram Na2S Put 3.23g Na2S in a 1L container with a loose fitting lid, add concentrated acid (12M HCl) in excess (until it stops fizzing) Collect it by water displacement: https://chem.libre...Water_Displacement NOTE: You do not actually want pure H2S. Look up the range of the detector and dilute the gas to the correct concentration. One way to do this is in the water displacement part - Let's say you want 1 liter of 10% H2S (still way too high!), then you get a 1L bottle, put 100mL water in it so there's 900mL air in the bottle, then do the water displacement just until the water is fully displaced. OR, collect pure H2S in a syringe (pressure pushes out the plunger) and squirt it into the test container. This way you can do a range of concentrations with minimal effort. Just make sure everything's sealed properly. Should calibrate at least 2 points (probably 3) - One near the middle of the detection range, and one at the bottom of the detection range. Note also: The numbers I gave here are totally ridiculous for real world scenarios but you get the idea - The "danger" level for H2S is 15ppm = 15 MICROliters of H2S per liter of air. Adjust accordingly. You can "serial dilute" to accurately measure such small volumes (1:10 H2S:air dilute that 1:10 in air becomes 1:100 H2S:air, you get the idea) Also, pre-mixed 15ppm H2S gas cylinders are readily available as "calibration gas" precisely for this purpose. Also "Multi calibration gas" cylinders. If you dropped $500 on a monitor then $100 on cas might not be a big deal, search for "calibration gas" on Amazon / your favorite retailer ON ANOTHER NOTE: O2 monitor is also a good idea. Any confined / unventilated spaces that have iron in them will slowly rust, eating up all the oxygen in the space. This seems to be like the #1 cause of death on merchant marine ships https://maritimeac...pace&searchsubmit=
[last edit 1/18/2021 7:07 PM by BudPiffo - edited 2 times]
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| plight
Location: Bay Area, CA Total Likes: 108 likes
| | | Re: gas detectors \ safety in mines < Reply # 13 on 1/23/2021 12:01 AM > | Reply with Quote
| | | Posted by entropy Do you think it's right to think it should be Ok with only O2 and H2S detector since LEL and CO are a risk in active place were machinery is used but not so much in a abandoned place ? If CO is still a risk, I could grab a 25$ battery powered detector like I have in my camper van.
| I’m currently wondering the exact same thing. For sewers: the main gases are H2S CO SO2 and Methane. Methane is non toxic, the risk comes from too much methane causing a lack of oxygen. The majority of 4 gas meters don’t include SO2, and since you can smell SO2 between 0.3 and 1ppm and the lethal levels are significantly higher I’m less concerned. If a lack of oxygen can be detected by troubled breathing, and an oxygen sensor, I don’t really need a methane sensor. (LEL/Combustibles). So if the BW Clip covers H2S and O2 for under $200, and the occurrence of CO is unlikely, do I really need a fancier 4-5 gas meter? I know nothing about mines or the gases that occur in them so I can’t help specifically for that. A CO detector is going to alert you if there’s any presence of CO. I would honestly prefer a meter which is going to tell me the exact level of concentration. The BW Clip equivalent of a Clip 4 that doesn’t require testing would be 3 individual units. One for O2, one for H2S, and one for CO. Around $300. It’s certainly a hard decision, the BW Clip is essentially an expendable. I don’t know how I feel about disposable equipment but it can reportedly last for 2-3 years. If your going to be in this for way longer, maybe purchase a 4 or 5 gas meter and send it out for calibration each time you go out. I’ve looked at used versions of the MSA Altair 4/5X, the MSA Orion, Dräger x-aM 2000 and 5000 as well as some QRAE detectors. It’s hard to skimp out on life safety equipment.
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| entropy
Location: Montreal\Sherbrooke généralement Total Likes: 34 likes
| | | | Re: gas detectors \ safety in mines < Reply # 14 on 1/24/2021 4:32 AM > | Reply with Quote
| | | Posted by plight
I know nothing about mines or the gases that occur in them so I can’t help specifically for that. A CO detector is going to alert you if there’s any presence of CO. I would honestly prefer a meter which is going to tell me the exact level of concentration.
| Good point, I'm lucky, there's a meter on my CO detector, its a Kidde C3010D. It refresh every 15sec and keep a track of the Highest level since last reset. It start beeping at 30ppm. It's kind of clumsy but for what I need it could be ok. I'll just have to make sure I don't drop it in a puddle. Posted by plight
The BW Clip equivalent of a Clip 4 that doesn’t require testing would be 3 individual units. One for O2, one for H2S, and one for CO. Around $300. It’s certainly a hard decision, the BW Clip is essentially an expendable. I don’t know how I feel about disposable equipment but it can reportedly last for 2-3 years. If your going to be in this for way longer, maybe purchase a 4 or 5 gas meter and send it out for calibration each time you go out. I’ve looked at used versions of the MSA Altair 4/5X, the MSA Orion, Dräger x-aM 2000 and 5000 as well as some QRAE detectors. It’s hard to skimp out on life safety equipment.
| Exactly, that's not where I want to skimp. Thank you for all the info. I'm probably going to buy a BW O2 and a BW H2S. I'm canadian, all this equipment is pricier up here so unless I find something serviceable locally at a fair price, I will have to choose the expendable option.
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| Samurai Vehicular Lord Rick
Location: northeastern New York Total Likes: 1900 likes
No matter where you go, there you are...
| | | Re: gas detectors \ safety in mines < Reply # 16 on 1/26/2021 11:48 AM > | Reply with Quote
| | | Posted by BudPiffo No joke, you can fart on a H2S detector to test it if its an "eggy" fart. Not good for calibration but good for lols / checking the alarm works. For better calibration: Sodium sulfide (Na2S, NOT sulfate Na2S04) reacts with most acids to produce H2S. It's pretty available on the internet. You can make a volume of known H2S concentration: Let's assume H2S is an ideal gas; then 1 liter H2S = 0.0414 mole H2S 1 mole H2S <-> 1 mole Na2S + excess acid 0.0414 mole Na2S = 3.23 gram Na2S Put 3.23g Na2S in a 1L container with a loose fitting lid, add concentrated acid (12M HCl) in excess (until it stops fizzing) Collect it by water displacement: https://chem.libre...Water_Displacement NOTE: You do not actually want pure H2S. Look up the range of the detector and dilute the gas to the correct concentration. One way to do this is in the water displacement part - Let's say you want 1 liter of 10% H2S (still way too high!), then you get a 1L bottle, put 100mL water in it so there's 900mL air in the bottle, then do the water displacement just until the water is fully displaced. OR, collect pure H2S in a syringe (pressure pushes out the plunger) and squirt it into the test container. This way you can do a range of concentrations with minimal effort. Just make sure everything's sealed properly. Should calibrate at least 2 points (probably 3) - One near the middle of the detection range, and one at the bottom of the detection range. Note also: The numbers I gave here are totally ridiculous for real world scenarios but you get the idea - The "danger" level for H2S is 15ppm = 15 MICROliters of H2S per liter of air. Adjust accordingly. You can "serial dilute" to accurately measure such small volumes (1:10 H2S:air dilute that 1:10 in air becomes 1:100 H2S:air, you get the idea) Also, pre-mixed 15ppm H2S gas cylinders are readily available as "calibration gas" precisely for this purpose. Also "Multi calibration gas" cylinders. If you dropped $500 on a monitor then $100 on cas might not be a big deal, search for "calibration gas" on Amazon / your favorite retailer
ON ANOTHER NOTE: O2 monitor is also a good idea. Any confined / unventilated spaces that have iron in them will slowly rust, eating up all the oxygen in the space. This seems to be like the #1 cause of death on merchant marine ships https://maritimeac...pace&searchsubmit=
| we tried the fart thing with our H2S crickets and sniffers when I worked ata paper mill (I worked in the pulp mill/recausticizing section)... it didn't work.
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