Location of NRV in Fuel Pipe Line

First, your schematic is too small to read or make sense of.

Second this sounds like homework (I hope).

Third, if you do not understand the purpose and function of the valves in the system you have no business working on them.

Finally, if you cannot understand the purpose and function of the process in place and the function and routing of the pumps, valves and piping, you are an accident waiting to happen.

So, sit down and sketch out the flows required to meet the functional requirements of the process at hand and figure it out yourself.

It is normal for NRVs to be downstream of the pumps, Guv. You really need to do a HazOp on the installation.

Dear All,

Thanks for your valuable replies, my intension behind asking question is not for telling you I dont want to study/understand/. Some buddy have designed this system but I am having doubt toward location/ positions.

If you people felt that I have no business with it. its not fine....! I dont know that is right, but I have rights to ask.... its wrong.....! I think this is the best platform to ask/share the knowledge, thats what I think and .

Still instead of anweringg me, you have given me this all statements. Please suggest me whether NRV should be at input side of pump Or output side when it is 2 pump bridge system one is on duty and other one is on stand by...............?

Come on! If you can't figure this out, give up.

What is the purpose of a non-RETURN-valve?

If one wants to keep a solution from RETURNING to its source, where should one place the non-RETURN-valve?

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Downstream, Matey. Downstream.

Non Returning Valves would of course be downstream. Since the purpose of these valves is uncertain, I believe the wrong acronym meaning has been used here. The devices appear to have No Redeeming Value over their Natural Range of Variability as they attempt to control the Nutrient Reference Values of the product they secrete.

I wonder if Norman Ray Vaughn will be upset with his initials used in vain.

What we have here is failure to understand simple concepts and to communicate.

OP says, "with manual operated gate valve, what is the position of the that manual gate valves. (I have considered it should be OFF/CLOSE for stand by, all the time). In case of any trouble with duty pump, a person should go physically on site to change the positions" why would one need any check valves?

Why can't " a person should go physically on site to change the positions" change the positions of the valves who's function/purpose the OP doesn't comprehend?

With pressure/flow switches, controls, motor operated valves and some knowledge, a person would not be needed to manually turn valve handles.

I am not sure what your local code(s) require on this installation but you really need to find out and adhere strictly to all.

Where I am currently employed and at locations where I have provided service to or worked at in the past:

1. All fuel pumps are required to have a check valve (NRV) immediately after the discharge of the pump.

2. All fuel pumps are required to have an isolation valve rated for use with flamable liguids and gasses immediately downstream of the check valve (NRV).

The NRV is there to prevent fuel from being pushed back through a non-operating pump.

The isolation valve is there to allow safe isolation of the pump and to allow maintenance on the pump and NRV without impacting the process.

BTW the NRV must also be properly rated for flamable liquids and vapor operation.

First, I think you are using NRV for non-return valve, is that correct? In my US experience, non-return valves are a specific type of valve used on steam boiler outlets - they serve as a block valve when closed (to isolate the boiler), and as a check valve when open (to prevent back flow of steam from other boilers in case of tube failure, for example).

I can't make out the valve symbols in your diagrams, but I see a bunch of tanks and a couple of pumps. I assume from your description that you have 2 pumps in parallel, one in service and one as a spare. Check valves are commonly used in this instance to prevent the discharge of the pump running from flowing backwards through the non-running pump. I have seen a few large systems where the check valve was eliminated by installing an automatic actuator on the discharge block valve, which was coordinated with the pump starter to start opening when the pump was started.

The check valve is almost always installed on the discharge of the pump, for 234 reasons. 1) Many times the pump installation is sensitive to NPSH requirements, and all unnecessary friction loss in the suction (such as a check valve) is eliminated. 2) If the check valve were installed on the suction side, all portions of the system back to the check valve would have to be designed for the discharge pressure. 3) The suction piping is often/almost always larger than the discharge piping, so a suction valve would have to be larger, adding cost. 4) Sometimes the suction velocity might not be high enough to fully open a swing check valve, adding wear to the hinge and pin.

In the end, though, you should understand the operability of the entire system. What I have described covers many systems, but each installation has to be reviewed for any potential exceptions.

5) Any component running loose as a result of inadvertent self-disassembly of the valve upstream of it will find its way into the pump, inevitably causing impeller damage there.

I will try to explain the system with an example and some diagram for the system.

Lets consider 2 tanks which supply to 1 day tank located at some fa off point using pumps. The general philosophy for working of pumps if 2 pumps are given is as you told 1 working and other in standby mode. The lcoation and type of valves completely depends on what has been agreed between the owner (plant owner) and the contractor. For my example i will consider to provide ball valves since they are best suited for the fuel oil application. Refer to the flow diagram below showing the same. The below filled valve is Normally closed and shall be opened only when has to be used. The discharge valves can be replaced with motorized valve to overcome any manual intervention in the operation.