6 replies to this topic

[Archaic]

I am a chemical process engineer with 45+ years experience and have never before come across a fire relief problem that has me completely stumped.

Client has asked me to size an emergency fire relief for a resin holding tank.

Information provided by the client.

 

Material is a proprietary terpene resin,

It is an NFPA Class IIIB combustible liquid

Molecular weight ~575-600

It has no melting or freezing point.

Has no boiling point.

Flash point 399.2 F

Softening point ~245 F

Specific gravity 1.05

Viscosity, 3765 cp at 150 C.(302 F)

Negligible vapor pressure, <0.001 mm Hg @ 20C

Auto ignition temp. 460 C (860 F)

Decomposes on “high” temperature, producing CO, CO2, light hydrocarbons. And a carbon char.

May contain volatiles, up to 0.15% volatiles, xylene/naphtha volatiles  

 

Additional information:

Tank size 12,000+ gallons

Tank located in same containment area with lower class flammables and combustibles.

NFPA 30 default is hexane which requires a rather large vent and client has already stated that as not acceptable.

 

Any suggestions will be greatly appreciated.

Thank you in advance.

 

[breizh]

Hi,

Consider the resource attached ( Protectoseal ). You may contact them to confirm your calculation .

Note : Can you ask your client to supply the data related to their product , in particular the latent heat of vaporization to avoid to use Hexane ,boiling point ,...? They should have a MSDS !

 

my 2 cents .

Breizh

Edited by breizh, 22 March 2021 - 05:42 AM.

[Archaic]

Thank you for the quick response Breizh.

Unfortunately, the only properties in the SDS are the ones I listed above.  Everything else is listed as not available.

Have asked client for heat of vaporization. Client doesn't have it. Says material will decompose before it boils.

The previous study, performed by a different engineering firm lists the relieving pressure at 1973 mm HG at relieving temperature of 1300 C which is why the client is asking for an independent review. 

Under the given constraints, I feel that this problem does not have a practical solution.

[fallah]

Thank you for the quick response Breizh.

Unfortunately, the only properties in the SDS are the ones I listed above.  Everything else is listed as not available.

Have asked client for heat of vaporization. Client doesn't have it. Says material will decompose before it boils.

The previous study, performed by a different engineering firm lists the relieving pressure at 1973 mm HG at relieving temperature of 1300 C which is why the client is asking for an independent review. 

Under the given constraints, I feel that this problem does not have a practical solution.

 

Then a rough estimation for EV sizing will be as follows

 

First you should calculate sonic velocity of the relieving vapor by:

v_s =sqrt(kgRT)

 

Then having the vapor velocity, delta p (1973 mm HG) you can obtain the EV diameter...

[breizh]

Hi ,

To me you should talk to vendor with the limited info on hands . What was the size of the EV from  the engineering contractor who performed the study ? 

Consider the link underneath to support your work ( tables) 

 

https://www.beamer-a... Vent Guide.pdf

 

To me  the money spent to protect the tank should not be the driver !  

 

Good luck

Breizh 

[Archaic]

Thank you gentlemen,

I don't have the details of the previous calculations. Summary is 161,000 CFH through a 3" vent with a 4 ounce set pressure.

At this point I am thinking to recommend a either a 24"  emergency accessway vent  which is inexpensive to install, or to provide separate containment areas and per NFPA 30, para. 22.7.1.1.3 not required to provide emergency venting.

[horatorres]

Terpene resin is a well know product for adhesive industrie.. I will recomend  you, that ask the client to get the data needed from the resins producer.. I wtll set the usual latam exporter of terpene resin

 

 

http://www.yschem.co...esin/index.html

 

Horacio