NFPA 22 is the standard for firewater tanks, however I don't think you will find any minimum distance between two tanks, other than adequate clearance for inspection and maintenance activities.
Separation of redundant firewater supplies (storage and pumping), e.g. at a large process plant with fire / explosion hazards should be based on a risk assessment so they are not subject to the same credible fire / explosion scenario. I thought I had a recommended separation distance for this item, but can't find it, typically at two hydraulically remote opposite parts of the plant firewater system.
Have you reached out to the site fire/property insurance carrier engineering department? They will give you what they want for sure since they pay the loss and have a vested interest in site fire protection. Even if the site is self insured at some point an insurance company will be involved in a large loss. Or ask the site for the letter from the insurance carrier for what they recommend. I did a ton of these types of letters and had many meetings to discuss our “recommendations” when I was on the insurance side before retiring.
Hi, ProSafPlant1
Do you have some guideline which you had recommended separation? Maybe just advise me of step or flowchart then I will make decision by myself. Anyway, I have to find local law to define the distance also.
Hi, LCREP
Could you advise me the website of the engineering department as your mention?
You will need to find out who the insurance carrier is to find the engineering department. Here is a global insurance carrier Factory Mutual aka FM website. They insure many chemical and hazardous operations.
Tor 19, I had checked my files and couldn't find any spacing between two tanks, assuming the purpose is to be able to take one out of service for periodic corrosion inspection.
I didn't see anything in NFPA 22 although you should verify that. NFPA standards are also free for online viewing, after signing up.