Risky to Run Two Gear Pumps in Parallel?

You are working with a positive displacement pumps, so I don't see why you can not put them in parallel, withou much risk.

Check the outlet liknes to handle the flow, These pumps will give (PD Pumps) almost constant flow, and pressure will be built up by the outlet restriction.

If the load is able to absorb the flow, it will be OK.

The Risk1: one pump shut off- recirculation through the shut off pump: put NRV (check valve) along with the isolation valves for maintenance purpose at the inlet and outlet. So thet you can take out this pump (shutting off isolation valves) without disturbing the running pump. And before the isolation valves are closed, NRV automatically takes over the function.

Risk 2: one pump closed- reduced flow. You should havd logics in hydraulic circuit to shut off a few outlets to stabilise the outlet pressure and flow. Else your burners will not get enough oil.

Motor power etc, I feel will not be constraint here.

There is no issue with running gear pumps in parallel in principle, as they are positive displacement pumps. A safety issue arises should one of the users shut down suddenly, so there needs to be a way of re-routing surplus fuel oil back to, say, the main storage tank. So provided there is some form of pressure relief to protect the pipework and a surplus oil return arrangement downstream of the pumps, then go for it in principle subject to a safety review at site.

Thank you

Useful information, I am quite satified!

It's all part of the service. There's no extra charge.

I presume that the pressure before the nozzles is important for the combustion quality. You could use one pump at constant speed to supply the minimal requested flow and regulate the speed of the second pump so that pressure stays constant which ever is the number of nozzles open or which ever is the flow through the nozzles if they are controlled. This control is a speed control based on a pressure feed-back.

Installing a pressurized accumulator/reservoir to absorb pulsation and provide a supply of fuel for a period of time, should one of the pumps hiccup, allowing some time for diagnosis and correction of any incidents, wouldn't hurt. Maybe a third pump in parallel as a reserve that could be cut in, in case of an inevitable pump failure in the future.

It is a common practice to use hydraulic pumps in parellel in hydraulic presses. Depending on the load, we used to switch on 2 to 4 pumps in our 5000T hydraulic press. It has been functioning satisfactorily for more than 20 years.

You can confidently connect them in parellel. Any marginal difference in output pressure of the 2 pumps, will be corrected by the system & you will get a constant pressure.

Hi,

You can use both pumps, but check the following:-

1] What flow rate and system pressure you need for optimised operation.

2]Fix spring loaded relief valves to meet your requirement from pump discharge to the suction pipe of the pumps with suitable isolating valves.

3]You can also fix second relief valve set about little higher ... say 5 % higher than the suction line and let the discharge be led to the fuel tank with a good sized pipe line.

4] You can also fix a pressure switch connected to a hooter to give you alarm.

thanks and regards

B.k.kar

If both pumps are pulling suction off the same line be sure that the line is sized properly so that the pumps are not suction starved. The piping should be set up as a "loop" - meaning a return line to the supply tank and the relief valve on the discharge side of the pump should be routed to the return line. In my plant the fuel oil supply "loop" feeds individual pumps located on the skid for each one of my CT's. Relief valves on these pumps are routed to the suction side. Edmund

you will get more flow, if the pipes are wide enough according to linght of pipes. If the pipes are to small for the flow you will get higher pressure so you have to check if the pipes are made for higher pressure or if you have security return valve.