3 replies to this topic

[mona1380]

Hello,

 

I need to fina a Nitrogen blanketing valve for a small PFA 55 galon drum with dip tubes.

The solvent in the drum has a flash point of approximately 30 C and the discharge rate is 0.3 LPM.

I am looking for a small blanketing valve, but I can not find anything in small size.

 

I really appreciate your help and guidance. I like to maintain the pressure at 7 psi during the priming.

 

Thanks,

Mona

[Art Montemayor]

Mona:

 

Please refer to the attached Excel workbook sketch and tell us if that is what you are proposing to do.  If not, then supply a corrected or revised drawing.

 

Before applying such an inerting design, you should establish the correct MAWP of your 55-gallon drum.  You should not just assume that the drum will safely sustain the proposed 7 psig pressure indefinitely.  You need to identify the correct, true MAWP of the drum.  The flat drum heads will be the weakest parts and these must be confirmed as safe for the proposed pressure.

 

The nitrogen feed control valve is easy to find.  I have used conventional, readily available 2-stage regulators for compressed gas cylinders such as Oxygen, Nitrogen, Argon, and CO₂ on similar applications in the past without any problems.  These are the common gas regulators found on Oxy-Acetylene cutting torches, for example, and can be furnished in most retail hardware stores or even Sears & Roebuck.  I would try a near-by industrial gas outlet company or store.  These regulators are field-proven, reliable, and very inexpensive.  I show a picture of a typical, 2-stage model.

 

The PVSV relief valve is another problem.  You should consult with such suppliers as ProtectoSeal, and others.  You may have to settle for a very over-capacity valve (like 2" +), but it will work.  Don't forget to allow for fail-open condition on the N₂ feed regulator.

 

 55-Gallon Drum Blanketing.xlsx   149.36KB   45 downloads

 

[mona1380]

Hi Art,
 
Thank you for your reply.
I have checked MAWP and  the drum and fittings can sustain the pressure of 7 psi.
 
I am looking for a blanketing valve similar to protektoseal, in the below link but in samller size.
http://www.protectos...me/series10.cfm
 
I searched different vendors, but I did not find a smaler size.
 
I have added the drawing to the spreadsheet.
 
thanks,
Mona  55-Gallon Drum Blanketing V2.xlsx   216.74KB   32 downloads

[Art Montemayor]

Mona:

 

I doubt if you will find any nitrogen feed control valve smaller than 2" for this service.  That's why I resorted to using the 2-stage regulator that I suggested you follow up on.  The model you show is an overkill for such a small application.

 

You will also find that the smallest pressure-vacuum relief valve on the market is probably 2" also.  If you cannot generate a vacuum in the 55-gallon drum, then I would just use a simple, home-made weighted emergency relief valve - similar to the ones offered by ProtectoSeal.

 

This is such a small application of blanketing techniques, that you are left to use what engineers are paid to do: use your ingenuity - as long as it is done in a safe and operable manner.