Questions on installations

[vecnaj1978]

Hello there
i recently visited a site where fire pumps has been installed, at first look of the installation i was not convinced about it. i need your expert advice on the below points

1. the installation was for fire pump pumps, there was no pressure gauges on the suction header, is this acceptable ?? if no then please advice why

2. the water is coming from the storage tank which is only 5 meters above the suction line of the pump, the outlet from the water tank is 3 inch and then connected to a 5 inch header, the pump suction is 4 inch, is this acceptable ?? if no then please advice why

3. The pumps is of capacity 1000 GPM, but the water storage grp tank is of only 45000 liters capacity connected to a municipal water line. the water will drain out in just over 10 minutes, please advice the recommended capacity of the storage tank

please help with your expert advice on this installation

thanks

 

[Artisi]

Sounds like a good installation for hosing the floor or washing your car, as for a fire pump installation - doesn't sound too effective.
Suggest you contact the local fire pump company / supplier, unless of course they were the one that undertook this installation.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[bimr]

Suggest that you retain someone that is knowledgeable regarding fire pumps.

 

[LittleInch]

vecnaj,

Have a look on the NFPA website for their recommendations - the standards are now free to download and provide a lot of guidance. A lot depends on your location and what you're trying to protect and what code or system or requirements the fire pump is designed to.

For your questions
1) Direct fed from a tank the value of a suction guage is not high. It's always good to see it for trouble shooting purposes and is quite cheap, but not essential.
2) I's a little odd and the nozzle seems a bit small, but providing the pump is getting a flooded inlet pressure above it's NPSHR value, then it is acceptable. Five inch is not a common size, but it is fine.
3) Capacity of pump might be 1000 GPM (is this US GPM or imperial GPM??), but what is the flow requirement?, i.e. what it is feeding? Monitors and hydrants have a flow requirement at a certain pressure as do sprinklers and this is how you determine the duty. The pump might actually be much bigger than the highest flow, so difficult to judge.
Capacity of standby tank (assuming no inflow from municipality) depends on the requirements. Oil and Gas facilities where back up from municipal fire fighters are available within a short time (15-30 minutes) commonly have 60 minutes, but as said above - first find your requirement then determine the reserve volume. If you can depend on the municipal supply then you might be able to argue a smaller tank size.

If the scenario is a "burn down" one then a minimum 10 minutes supply might be enough to evacuate everyone and not actually fight the fire.

Some more information on "the site", its regulations and requirements and what the fire pump is feeding will help a lot.

Hope this helps.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[vecnaj1978]

Thank you all for the assistance

 

[bimr]

Answers:

1. No. Pressure sensing line for low pressure is required.

2. No. See Table 4.26 (a) Minimum Pipe Size (in.) is 8-Inches

3. The insurance underwriter typically outlines the water supply requirements. Generally, a 2 hour water supply is required.

This installation seems to be poor. Since this is a life safety issue, a competent person should review it.

Please refer to the attachment as it outlines NFPA 20 issues.