7 replies to this topic

[Meysam_45000]

Dear friends,

 

I have a question about the maximum seal flush temperature of centrifugal pump. We have some centrifugal pumps which their sealing plan are based on API Plan 21. We have always a repeatable problem with adjusting the highest seal flush temperature that we have to turn off the pump and clean the water-cooler of seal flush.

 

Moreover, I have found some data on datasheet of mechanical seal (manufactured by John Crane). It said that the flow of seal flush 51 l/min at 100°C. This temperature is far lower than the temperature of seal flush even if we use the clean water-cooler for the first time. It seems that this temperature is not the normal or highest seal flush temperature.

 

To sum up, I want to know how to find the maximum acceptable seal flush temperature for adjusting the cleaning time of the water-cooler. As you probably know we have a Local Temperature Indicator on the seal flush stream which is for surveying the condition of water-cooler.

 

It would be very grateful if you could help me.

[Rahimzadeh]

Dear Meysam:

I read in some document that recommend max.seal flush temperature is 60 degree centigrade.

best

M.R.Rahimzadeh

[Meysam_45000]

We have lots of Hot service centrifugal pumps which are working in from 150 C up to 205 C (seal flush temperature) without any problem. I think what you said is not practicable as the flow of cooling-water and size of Cooler.

[V Ramesh]

The maximum seal flush temperature is largely dependant on two factors- the stuffing box pressure and the vapourisation temperature of the fluid at the stuffing box pressure. For the seal to work properly , there must be a sufficient margin between the vapouristaion temperatire and the flush fluid temperatire. A safe margin will be 20 deg C. Typical flow rates will be 5 l/m to 10l/m. This can be achieved by a suitable orifice in the flushing line and by fitting a close fitting throat bush at the bottom of the stuffing bax.The HE for Plan 21 should be sized suitably to provide this temperature at this flow rate.

Hope this helps.

V.Ramesh

[Rahimzadeh]

Dear maysam:

Please tell me what kind of liquid you pump their temperature?

Best Regards

[Meysam_45000]

Dear m.r.rahimzadeh,

 

We pump hydrocarbon (c10-c13) and the temperature is about 240C.

 

Thank you, in advance, for your help.

[Meysam_45000]

Dear V Ramesh,

 

Could you please state your resource for (safe margin will be 20 deg C. Typical flow rates will be 5 l/m to 10l/m.).

 

Many Thanks.

[breizh]

Meysam_45000,

Probably good to consult the big names : John Crane , Burgmann , Flowserve and others .

 

They are the specialists !

 

Note : You will find temperature indication in the document attached !

 

Breizh

Edited by breizh, 15 August 2014 - 12:48 AM.