Ethylene Oxide PPM conversion

[AlCivic]

Hello, I have a problem at work which I could do with some help with. I am from a mechanical discipline so any help appreciated.

I have some medical parts which have been sterilized using Ethylene Oxide gas. The parts still have EtO residuals trapped in them. To accelerate the degassing of the product the product is heated for 24 hours.

The parts are placed in a chamber and heated to 43 degrees C.
What I need to work out is EtO gas ppm from 0.267 mg per litre.

The 0.267mg/l figure was calculated by taking the total measured EtO gas remaining in the product and the volume of the chamber.

Any help appreciated.

Al

 

[dcasto]

is that ppmv or ppmwt?

ppmv .267 mg/liter, MW air 28.8503 MW EtO 44.0520

density of air 1.222 KG/M^3

density of EtO at 43 C and 1 atm = 1.222 * 44.052/28.8503 = 1.8659 KG/M^3

1 liter of air weighs 1.222 grams

there is .267/1000 grams EtO per 1.22 grams air or .00022 per 1 or 218 ppm by weight

or .267 mg occupies .267/1000/1.8659 or .000143 liters so the EtO is .00498 per 1 which is 143 per million by by volume.

 

[mbeychok]

dcasto:

I have not checked your calculations, so I have no comment on them.

However, I think that you should also specify at what temperature and pressure your air density was calculated. I assume it was the same 43 deg C and 1 atm at which you calculated the EtO gas density.

Regards,

Milt Beychok

Milton Beychok
(Visit me at www.air-dispersion.com)
.

 

[25362]

I also assume the calculations were done on dry air, moist saturated air would give higher ppm values on a weight basis.

Anyway, these concentrations are way above the recommended TWA and TVA limits.