6 replies to this topic

[Sherif Morsi]

Hi,

 

Currently a biocide injection line is connected to the drains tank to for intermittent injection. Operations requires that the same biocide be delivered to biocide cells for storage elsewhere in the facility. Under the new arrangement, the biocide will be injected into a vertical line coming from the seawater distribution system (this SW line is not used anymore, the butterfly valve is normally closed - not locked closed).

 

I have two options:

Option 1: Just install isolation valves on the 2 branches as shown in the attached sketch

Option 2: Install an isolation valve and a check valve on the branch connecting to the vertical section of the SW line to avoid back flow in case the SW supply is resumed for any reason in the future.

 

Your thoughts?

 

Thanks,

Sherif

Attached Files

•  2017-06-26 16.45.39.jpg   111.48KB   3 downloads

[Mahdi1980]

Hi,

If your vertical sew water tank is pressurized or the injecting line is connected to the bottom of the tank such that a head of liquid is above the inlet nozzle,you are recommended to install option 2 including both of isolation and check valves to avoid back flow.

Anyhow, Option two is a safer choice.

You have injection/dosing pump in your system. don't you?

[Sherif Morsi]

Yes, it's a small metering diaphragm pump.

 

None of the tanks is pressurized. Both tanks are atmospheric. The injection point is at EL+115.0, the inlet nozzle on the tank is at EL+88.5 and the top of the tank is at EL+90.4.

 

I am more inclined towards option 2 as well given that there is no guarantee that the SW line will not be used in the future! 

[Bobby Strain]

One would typically use a separate pump for each service.

 

Bobby

[Sherif Morsi]

Completely agree Bobby, but the cells are filled once a week plus this is an existing facility and clients are trying to capitalize on each and every thing they have to reduce their costs given the status of the industry as a whole.

[Sherif Morsi]

Hi,

If your vertical sew water tank is pressurized or the injecting line is connected to the bottom of the tank such that a head of liquid is above the inlet nozzle,you are recommended to install option 2 including both of isolation and check valves to avoid back flow.

Anyhow, Option two is a safer choice.

You have injection/dosing pump in your system. don't you?

 

The inlet line is connected to a nozzle at the bottom of the tank. The tank is not pressurized.

 

But, the injection point is way higher than the tank itself, then the line runs all the way down.

 

Do you think we still need the check valve?
 

[Mahdi1980]

No, I don 't think so.