3 replies to this topic

[mccombe_kate@hotmail.com]

Hi All, 

 

Is it sufficient to use an overcurrent trip on a PD pump motor in place of an internal kickback or discharge PSV to prevent overpressure?

 

Thanks, 

Kate

[Bobby Strain]

No.

 

Bobby

[fallah]

 

Is it sufficient to use an overcurrent trip on a PD pump motor in place of an internal kickback or discharge PSV to prevent overpressure?

 

 

Kate,

 

No, because although the motor has its own protection against overcurrent it's not intended to be tripped due to any process upset leading to discharge overpressure. 

[ankur2061]

Hi Kate,

 

In services involving slurries and heavy solid content as suspended impurities in the pumped liquid, the following can be adopted:

 

1. Provide redundant pressure trips (2 in series) to trip the pump on high discharge pressure

 

2. Provide combination of Rupture Disk and PSV (rupture disk upstream and PSV downstream)

 

3. Additionally as suggested by you an overcurrent trip may also be provided

 

In slurry service and service where the pumped liquid has high solid content PSVs will plug over a period of time, and unable to provide overpressure protection. From plant experience I can tell you that for Titanium dioxide slurry in MEG we had provided two pressure switches (transmitters) in the pump discharge line for overpressure protection and it worked fine. No PSV was installed.

 

Regards,

Ankur.