Recent content by npf

David: Thanks for your response that helped me a lot in understanding the concept. As I mentioned we have a recycle line from the discharge of the compressor that ties back to the compressor KO Drum. I think that is the antisurge protection but it is more common on dynamic compressors. Do you...

All: Currently I am working on oil flooded rotary type compressor P&ID. It compresses propane vapor from 15psia at -42.5F to around 313 psia. The slide valve will operate based on suction pressure control. Could anyone expain to me this control scheme i.e what happens if pressure is too high or...

All: Currently I am working on Air Cooler P&ID. Here are the details of the air cooler- Its a forced draft, single bay, 2 fan/bay cooler. The propane vapor enters at 210F and 300psig and leaves as liquid at 120F. The deltaP across the cooler is 5 psig. The motors are of VFD type. The speed of...

All: Thanks for the information. Right now we are working on LPG terminal project.I will try to look onto NFPA58 for more information. Regards, npf

All: I am currently working on LPG terminal project. For LPG line sizing, what pressure drop and velocity guidelines should be considered? LPG operating temperature is about-40F Also I am trying to find out the isolation philosophy to be used for isolating piping and equipments and where an...

All: Thnaks for the comments. I am planning to take a quick shot at the fire case and look at the relief load. SeanB: The pipe is insulated and the operating temp is around -260F and this relief valve is placed between 2 fail closed control valves. Regards, npf

All: I am sizing thermal relief valves for liquid LNG. Typically we do not size those and use default, but the client wants to see the calcs. These valves are located on 26" diameter long and short run of piping. The pipe length is approx 1000ft and is insulated. Do we have to consider...

JL Seagull: Thanks. Is that the reason why I do not see any instrument air supply connection to the 3 way valve? Regards, npf

JL Seagull: Thanks for your valuable inputs. I still have some doubts. As per the sketch the solenoid sends pnuematic signal to the control valve( per the instrument line symbology). If thats the case the electropnuematic positioner will convert the electric signal received from the HIC to...

All: Thanks for the responses. Regards, npf

JL Seagull: I appreciate your help.I got a better understanding now. Regards, npf

JL Seagull: Appreciate your explaination on the control scheme. It improved my understanding. I have some doubts In your reply you mentioned HIC as the operator throttling adjustment, how does that work actually? I saw some Solenoids actuated by DCS and some by SIS. What difference does it...

Dan: Thanks for your response. Just to make things clear, I have attached a sketch, HV-1000. If I undertsnad correctly we receive pneumatic signal from the controller (for eg 3-15 psig) that would cause the valve to close or open. If possible could you in short expalin whats going in that...

All: I am working on P&ID's on an LNG project. I have globe valve w/ electro/pneumatic postioner(actuator). It also has a hand jack. The valve tag is HV-XXXX A 3 way solenoid valve is feeding the actuator. Could any one tell me the use of the electro/pneumatic positioner? Would a diaphragm...

All: I am new to the process industry.I am working on LNG project in the development of P&ID's. I am trying to understand the logic (or undertsand how it is trying to control) for 2 valves HV-1000 and HV-500 marked w/ an arrow in the attachment. A sequence of operation would be good way to...