Posted By Chris Kelly Assuming I am understanding you correctly, you need to be careful here as, although the gas is asphyxiant rather than toxic, the sudden change in oxygen content can lead to sudden loss of consciousness. Accordingly it is safest to consider the atmosphere as if it contained toxic gas. You need to consider 'lack of oxygen' rather than the quantity of the gas. Get a gas meter and test your oxygen level - if it is below (or above) the % then it is dangerous. Regards, Chris

Posted By Neil Pettitt Not my field but suspect that the F Gas Regs might apply.

Posted By D. Hilton Assuming no ventilation and instantaneous homogeneous mixing a concentration of 6.8% or 291.7 m3 of R410A is required to reduce the Oxygen concentration to 19.49%. Room Vol 40 m3 Oxygen in room 836 m3 Nitrogen etc 3160 m3

Posted By Phil Rose I have got to admit that I am impressed with the calculations. I suggest that confined spaces regs apply and also suggest that a reasonably simple precaution would be to use gas monitoring.

Posted By CFT Why is the system leaking, or why is the gas present? Specifically F-gas regs are responsible for the blended gas, and CS as stated for the situation. This is usually for AC equipment. It is also incredibly quick to clear. More concerned why it is happening though. Curious.

Posted By D. Hilton Ronofcam Use of Ideal Gas Law and Dalton's Law ;] or in other terms: The Oxygen concentration in air is 20.9% If we take 19.5% Oxygen as the safe minimum limit then we know that 1.42% of Oxygen must be displaced. to displace 1.42% of Oxygen we must displace an amount of air containing that Oxygen. In other words 1.42/20.9*100 = 6.83%. As we are displacing the 6.83% of Air with R410A we can say that the concentration required to deplete the Oxygen content within the room is 6.83%. Simples Obviously if you want to calculate the conc of the chemical of concern required to result in an Oxygen concentration of 18% then 2.9/20.9*100 = 13.8% Regards D

Posted By D. Hilton Also, it's handy to know that 6.83%, 68300 ppm, 203922 mg/m3, 203 g/m3 is the concentration of any asphyxiate that will result in oxygen depletion below 19.5% regardless of the size of enclosure.

Posted By D. Hilton It's not as simple as that Bob, it depends on the level of physical activity in conjunction with the ambient concentration of oxygen inhaled. The ambient O2 concentration effects the level of saturated blood within the body. A decrease in the saturated blood concentration (SaO2) of 10% provides a reasonable chance of recovery without physical harm or fatality. A decrease of 15% SaO2 will lead to physical harm and or fatality. At rest ambient O2 levels will be lower than during moderate physical effort. So during escape or carrying out moderate work, an ambient O2 conc of 18% will result in a reduction of SaO2 of 10%. While an ambient O2 conc of 17% during the same scenario will result in a reduction of SaO2 of 15%. a difference of 1% conc would make the difference between life or death in such a situation. For the above reason 19.5% O2 conc is selected as a safe limit. NB Decrease in SaO2 can be calculated as EXP(10.5-0.455*(Amb O2 Conc Inh). Please note this does not include the effects of inhalation of CO or other fire effluent. Regards D

Posted By D. Hilton 8.66 litres or 8.73 Kg liquefied gas expansion factor at 293K = 336 (Rho Liquid/Rho Gas) 2910 litres gas in room to give 6.83 % conc

Posted By D. Hilton Good thing you asked. The 2.91 m3 is based on the sum of the partial pressure of 3 gases into a theoretical sealed box which results in a slightly higher volume of gas required to provide the 6.83% concentration within the room. So to clarify: Room volume 40 m3 Concentration of gas required is 6.83% of 40 m3 (2.73 m3) From BOC data: Liquid density 1.09 water @1000 kg/m3 gives (1090 kg/m3) Gas density 2.5 Air @ 1.2 kg/m3 gives (3 kg/m3) Liquid to gas expansion calculated as Rho liquid/Rho gas (1090/3)giving an expansion factor of 363.3 (note error in previous reply) We know that 2730 litres of R410a is required to result in 6.83% concentration. 2730 litres gas / 363.3 expansion factor gives 7.51 litres of liquified gas within cylinder. 7.51 litres of liquid x liquid density 1.09 kg/litre gives 8.19 kg liquid gas. Regards D

Posted By D. Hilton happy to help

Posted By D. Hilton Bob :}