Dear all,
we have an issue with my current design of tank overfill protection.
we have chemical storage tanks with foam chambers installed at tank side. As per API 2350 recommended, the minimum distance between LSHH level to overfill is 3 inches (76mm).
Current design the response time is calculated from tank LSHH level to the bottom of foam chamber nozzle and it meets API recommendation (it equals to 2 minutes).
However, Client has just provided us their design guideline that response time from LSHH level to overfill level should be minimum 2 minutes plus a margin of 2 minutes. it means total of 4 minutes from LSHH level to overfill.
We already purchased all level switches (LS and the their length can not be adjusted. So, initial we planned to trim the nozzle of LS or relocate the nozzle location to meet the 4 minutes of response time (avoid a new order).
However, someone in my team defends that the foam chamber is designed to go up to the top of tank, create an U turn before going down to ground. Hence, the overfill level can be considered higher than foam chamber nozzle as the current calculation. therefore, 4 minutes that Client standard can be met. So we don't have to make any change at site.
If anyone of you have experience with this matter, could you please advise me if with this kind of foam chamber, could the overfill level be higher than bottom nozzle?
I attach here a snapshot for tank model for information.
I do appreciate all opinion.
Thank you
Attached Files
Edited by linda_pro, 23 October 2019 - 09:32 AM.