Buried pipe in fire protection system

It can be buried.
I would not use butterfly valves at the flow meter.
They are OK for flow regulation from the pump.


Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

Is there a reason to route the relief back to the tank? Normally, there is no flow from a relief valve and the valve discharges to atmosphere.

What is the purpose of the flow meter? To check the pump flow rate? You may also confirm the flow rate using a monitor or fire hydrant and discharge to atmosphere.

Yes, the pipe can be buried. Be sure to follow FM guidelines for the components.

Why are you making that question? In a fire water system, any pipe if well protected against corrosion can be buried I don´t understand your doubt!?

The question arises because in an article on the internet I read that in fire systems it is recommended that the return line to the tank of a PSV in a fire system go aerial and I wanted to know if this recommendation is in the standard or manual. In the case of the flow meter, although NFPA 24 indicates that the return line must return to the tank or optionally be re-injected into the suction line, it does not mention whether there is another restriction on mounting the instrument apart from the distances upstream and downstream of the instrument before an accessory.

Thank you very much everyone for the help.

Hi,
What is the point to connect the outlet of the PSV back to the tank? How will you know that the valve is activated? Should be routed to the ground.
What is the usefulness of the flow meter? Is it to monitor the pump during periodic tests? If this is the case, I will use a portable flow meter well calibrated.
Butterly valves are not isolation valves, review your PID accordingly, you may want to use them to throttle the flow at the outlet of the flowmeter.
If pipes have to be buried, consider wrapping material (polymer film) to prevent corrosion.

Pierre

There is no sense to route the underground lines for the pump discharge water returns.
There is extra cost for installing the short round of U/G pipes. Also, it can be an issue for the inspection and maintenance of the U/G lines in the future.
IMO, the tank nozzle of the water return line can be located at minimum height on tank shell instead of the tank roof, as there is no air gap requirement for the pump discharge return.