3 replies to this topic

[karthik.kattupalyam]

Dear sir,

 

We are facing a regular problem of pump seal leakage and chouck problem, while transfering the material.

It is not final product, it is from reaarangement to isolation process. because of melting point 65 deg C we are flushing the line with hot water(80 deg C) before and after of the transfering the material, for one batch 7000kg.

 

material data: melting point 65 deg C, cp=0.55 kcal/kg k, Density=1.25gm/cc

 

pump data: I got from maintaince.

cap:20m3/hr , 20m head, Impeller=PP, and seal = SS316 

stand by pump also  having same data.

motor's=1. 1440 rpm and 5hp

              2. 1440 rpm and 7.5hp

 

pipe line PP with FRP coating and suction and discharge of pump are 2 inch, I know suction should be greater than dischagre line, is suction and discharge line also effect the seal??

 

My question is which Material of construction of pump is suitable for such kind of acidic material, and also i want to know moc of pumps with different materials. please suggest me.

 

thanks.

Edited by karthik.kattupalyam, 18 November 2013 - 05:09 AM.

[Ming Hooi]

Hello Karthik,

 

There are pumps in the market that come with heating jacket so that you can keep the fluid above its melting point.

 

If you use gland packing, you need to maintain the pump by periodically tightening the packing.

If you use mechanical seal, replacing the seal every 2 to 3 years is very normal. There are systems to pressurize the fluid so that it doesn't leak out from the seal, and there are systems to contain the leaking fluid so your pump area is kept tidy.

But in both cases above, wearing of the seal is "expected" because it serves to protect the shaft or the shaft sleeve which are much more expensive to replace.

Discuss the selection of your seal material and type with your supplier based on your process requirement (fluid type, operating temperature, pressure, intermittent start-stop of the pump)

 

You may want to know that there are pumps in the market that use magnetic drive, i.e. truly sealless pumps so that you don't have leakages problem. I can think of CP Pumpen and Allweiler who can help you solve your problems.

 

 

Ming Hooi

[sukanta87]

Hi karthik,

You can consult with the manufacturer of the pump.

Suction pipe size and discharge pipe size can be similar with no problem but it's better practice to have larger size of the suction pipe (or using a reducer at the discharge line if the discharge pipe size is not smaller than the suction). If the suction is not sufficient to provide the required NPSH to the pump, it may happen cavitation which damages the impeller mainly but may affect on seal. Check the strainer of the pump.

You can think about CP pumps what Ming discussed. API 610 has the details about the MOC of pump. Check the technical data sheet of the pump and verify the operating conditions like temperature, pressure and materials it can handle.

[fseipel]

Jacketing is great for extremely high temperatures.  Unfortunately that's probably a major retrofit since you're currently using PP pipe -- to eliminate flush procedure you'd have to jacket the pump and the piping or heat trace it with electrical heat tape.  You state pump impeller is PP; I would suspect pump itself has a polymeric casing.  That said, if you're on a tight budget, rather than buying a very expensive PP lined C/S head, steam or oil jacketed 100 GPM pump, you might want to try flushing the seal or gland with hot water if it has provision to do so (insert rotameter, small steam jacketed segment of pipe or tubing to heat the water), and/or placing the entire pump in a hot box, that is, a rigid, insulated box, heated electrically or with a steam coil on its sidewall.  Be sure not to overheat the plastic.