Determining API Standard Flush Plan & Auxiliary for LPG Pump (OH2)

You give no operating conditions, but generally I would choose Plan 11/52. That is a flush from the discharge of the pump into the seal chamber and dual seal with non-pressurised buffer fluid.

Plan 11/76 is cheaper than the dual seals and system of the Plan 52 as it utilises a secondary sealing device (dry running. contacting or non-contacting) of some sort to divert the leaked gas to safe location with the aid of a purge gas.

11/52 would be my very strong recommendation as you have a full service second seal should your product seal fail. It is also very easy to determine the condition of both seals by using level and pressure indications on your seal system.

Hi The Prof..

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The operating condition is as follow:

Liquid: LPG (SG: 0.56, Viscosity: 0.15 cP)

Pumping temperature: 30 C

Corrosion Caused by: Etyl Mechaptan (LPG Odorizer)

Capacity: Max 167 m3/hr

Discharge pressure: 10.26 kg/cm2A

Suction pressure (min / max): 6.38 / 11.57 kg/cm2A

Hydraulic HP: 19.44 kW

NPSHA: 2.5 m

Thank you very much for your help.

Hi Premium,

I would use 11/52 - it is just that much safer (and in my opinion more reliable). The money saved by going for 11/76 is just not worth the added risk you are exposed to.

Hi The Prof,

Will consider your answer. Many thanks.

Oya, what are the considerations or critical points in determining API Flush Plan? Maybe someday we would face another tricky problem regarding this kind of matter.

Thanks so much.

If someone want to give additional information? I really really appreciate it.

If ingress of any fluid inside LPG (Pocess side) is not allowed in that case,Plan 11/52 is more reliable and recommanded. With seal configure C2A3A11/52 with Face-to-Back (FB) Seal arrangement as per Figure - 5 of API 682 3rd edition.

Otherwise, You can go for either C2A3A02/53 or 53B FF tye (Also, C2A3A11/53 FB Tye) with external pressurized seal Plan arrangement called Plan 54 also.

Regards,

Nilesh.