Marcos:
In my response to your post, I did not mean to imply that your application does not merit any emergency design consideration. The API Standard 2000 states:
“This standard covers the normal and emergency vapor venting requirements for above-ground liquid petroleum storage tanks and aboveground and underground refrigerated storage tanks designed for operation at pressures from vacuum through 15 psig (1.034 barg). Discussed in this standard are the causes of overpressure or vacuum; determination of venting requirements; means of venting; selection, installation and maintenance of venting devices; and testing and marking of relief devices.”
Under Special Notes, it further states: “API standards are published to facilitate the broad availability of proven, sound engineering and operating practices. These standards are not intended to obviate the need for applying sound engineering judgment regarding when and where these standards should be utilized. The formulation and publication of API standards is not intended in any way to inhibit anyone from using any other practices.”
You are not storing a hydrocarbon, but instead are dealing with plain water. It is perfectly admissible to apply API 2000 to your project - even though you are not dealing with relatively higher vapor pressures that are flammable and possibly explosive. The term “emergency” in the API standards is normally related to the ignition, spillage, over-pressure, over-filling, or release of potentially dangerous hydrocarbon fluids.
In your case you are dealing with a relatively benign fluid. But, nevertheless, the storage and handling of even water can cause some unforeseen hazards - and these, in my opinion, merit that they always be at least considered before implementing a project to completion. For example, have you taken into consideration:
- The sudden rupture or disconnection of a hose while filling or pumping-out? What would be the possible vacuum caused in the tank and can your vent handle the possible sonic velocity in the vent nozzle?
- Do you have credible, safe protection against a tank over-fill? If your vent cannot safely handle a potential overfill, the tank might be over-pressured and rupture.
- Your tank will go from empty to full in approximately 30 minutes as designed. Are your operations manual or automatic? Can your local operators react fast enough to a potential overfill or sudden excessive pump-out?
Depending on where your tank is located, these could be defined as emergency situations.
I hope I have cleared up my comments on a safe storage tank design. The spillage or leakage of water may not be considered hazardous. But the sudden rupture or collapse of a storage tank certainly poses a potential danger to humans and its surroundings.
Cumprimentos.