Mechnical Sealing on CO2 Integral Gear Compressor

[planck121]

Hello,
I am in the process of selecting/deciding on a mechnical sealing arragnement (single versus dual/tandem) arragnment for a CO2 integral gear machine with the EPC firm. While selecting seals (dual versus single) is highly dependent on the nature of the process. What is the general consensus out in the engineering world regarding the seal on such a machine. The process does not contain H2S or other toxic/flam or dangerous process. Will be located in a building. My personal preference inspite is towards a dual mechanical seal arragnemenent as opposed to single seal. However, is there anything that the single seal provides (i.e reliability or other technical advantage) over a dual seal system. In any case if we fail the seal the machine will have to be pulled apart.

Thanks for the input in Advance

 

[RotaryG]

planck121,

CO2 is heavier than air and you are locating the compressors in a building. You need to provide best sealing money can buy.

 

[flexibox]

If you use a single seal then in the event of a seal failure CO2 leakage will be in the building. If you can live with that then it's ok. As there is no specific information on the duty conditions it's a little hard to make an informed recommendation. Having said that my preference is dual pressurised because you guarantee a stable fluid film at the seal faces, and as a result should be more reliable than single seals. Secondly you can monitor what's happening with the seals and can guarantee zero CO2 leakage to atmosphere or in the building.
Only problem is cost of systems and level of instrumentation. I would recommend API Plan 53B. I am sure thre may be a single seal available but if you want reliability then I would vote for dual seals!

Trust this helps