PSV on Anhydrous Ammonia Storage Tank
PSV on Anhydrous Ammonia Storage Tank
(OP)
Need to size PSV on Anhydrous Ammonia Storage Tank. Is fire case is credible scenario for Anhydrous Ammonia? Thanks for your inputs.
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PSV on Anhydrous Ammonia Storage Tank
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RE: PSV on Anhydrous Ammonia Storage Tank
OSHA 1910.111 - Storage and handling of anhydrous ammonia
Good luck,
Latexman
RE: PSV on Anhydrous Ammonia Storage Tank
RE: PSV on Anhydrous Ammonia Storage Tank
Unfortunately you have to convert the flow rate in air to equivalent flow rate of ammonia to utilize the API relief valve sizing forumulas.
Another standard that is utilized is "The Compressed Gas Association" CGA G-2.1 which essentially replaced ANSI K61.1.
The OSHA 1910.111, and CGA G-2.2 / ANSI K61.1 are very similar.
I like the ANSI K61.1 because it calculates the required relief valve capacity in terms of lb/h of ammonia rather than SCFM of air.
Good luck
RE: PSV on Anhydrous Ammonia Storage Tank
Agricultural Ammonia Institute pamphlet, Standards for the Storage and Handling of Anhydrous Ammonia
http://canlii.ca/en/ca/laws/regu/crc-c-1146/latest...
I would be surprised to find the sizing requirement different from OSHA or K61.1, but I don't have any access to the AAI pamphlet.
RE: PSV on Anhydrous Ammonia Storage Tank
Thanks GHartmann
I don't have ANSI K61.1 or equivalent CGA G-2.1. Appreciate if you could provide it.
I need procedure to size or specify PSV based on Anhydrous Ammonia Storage Tank Size
RE: PSV on Anhydrous Ammonia Storage Tank
You will get the correct size if you use the API case for wetted fire assuming the tank area is 100% wetted. You will need the latent heat of vaporization of ammonia to complete the calculation.
Here is a source to guide you futher:
http://www.tannerind.com/PDF/blue-anhy-amm.pdf
RE: PSV on Anhydrous Ammonia Storage Tank
RE: PSV on Anhydrous Ammonia Storage Tank
I talked to Fabricator regarding it and he mentioned that it's a two port spring loaded valve which is slightly different than API orifice designate PSVs. I did calculation using API method, which gives me Orifice Size J. There is already one tank installed on site, which has different PSV than what I Calculated. Appreciate your inputs.
RE: PSV on Anhydrous Ammonia Storage Tank
Another way to make the calculation is to size the relief valve using the values from OSHA 1910.111 in SCFM of air.
Then using that size, determine the quantity of ammonia that will pass through the same relief valve.
The formula for weight from ANSI 61.1 is:
W = (34500 x F x A^0.82) / L
F = Environmental factor = 1.0
A = surface area ft2
L = latent heat of vaporization BTU/lb
W = lb/h
Good luck!
RE: PSV on Anhydrous Ammonia Storage Tank
Good luck,
Latexman
RE: PSV on Anhydrous Ammonia Storage Tank
The AAI had input into and sponsored the CGA G-2.1 / ANSI K61.1 , but somewhere along the way withdrew the sponsorship (1999 K61.1 forward)
OSHA 1910.111 incorporates much of ANSI K61.1
Thus, the Canadian regulation will be very similar to OSHA.
But, as already stated this needs to be verified.
RE: PSV on Anhydrous Ammonia Storage Tank
RE: PSV on Anhydrous Ammonia Storage Tank
Please correct me if I am wrong. Thanks
RE: PSV on Anhydrous Ammonia Storage Tank
Also, I don't think a PSV Engineer can fully delegate safety to a vendor. There has to be check and balance.
Good luck,
Latexman
RE: PSV on Anhydrous Ammonia Storage Tank
Latexman is correct. On page D9 in the catalog is the capacity required by ANSI K61.1 which specifies the capacity in SCFM of air (this table has as its roots the API fire calculation for wetted area). Then the vendor has gone off and done some more calculations to determine the area of his valves. Since these valves are not "typical" relief valves they may use some different formulas than specified by API.
I think what you need to do depends on what type facility you have and how big your tanks are.
A small nurse tank at fertilizer distributor might be OK with the REGO valves. However, if you are in a big chemical facility or power plant, you might want to have a more typical ASME style relief valve.
I would ask REGO if they comply with the OSHA guidelines and CGA guidelines as to the relief valve requirements (they are very specific in the regs).
Sorry if seems I am beating this to death. Just trying to keep you out of trouble.