Bladder accumulator to avoid degassing

[Petercooper]

I have a high pressure, high temp API centrifugal pump application that will run with a plan 53B double mech seal. I am planning to use an accumulator with a bladder as the seal pot to avoid N2 degassing on the seal chamber.

Does anyone have experience with this seal? Thinking of using this bladder accumulator

http://www.hydac.com.au/accumulator.aspx

as suggested by one of the posters in another thread if this is the best option.

 

[Pumpsonly]

Plan 53B is a proven system. You mentioned high temp and high pressure but did not give any details.

 

[PumpSmart]

Petercooper,
In my experiencie, for seal mfg warranty purposes we used accesories made by the same seal mfg.
High Temperature bottom pump in petroleum refinery (320 to 360 C), start using plan 52, then plan 53A, but because of reverse pressure we change mechanical seal too.
We use plan 53B and Plan 54 for the same service too, but depends of water available, fluid for primary fluid available, budget, maintenance experience, seal chamber pressure, pumping fluid, temperature, etc, etc to make a good selection.
As previous asked by Pumpsonly, will be great to have more information.
I hope it helps.

 

[Airsporter1st]

Plan 53B, by definition (see API 682 3rd Ed) utilises a bladder accumulator to provide a store of barrier fluid at the required pressure for a dual pressurised mechancal seal.

The manufacturer I am most familiar with is fawcett Christie Hydraulics. See internet address below (I don't yet know how to insert a live link).

http://www.fch.co.uk/uk-home.htm

Generally speaking with a plan 53A, anything above 10 barg barrier pressure brings with it the risk of nitrogen dissolving in the barrier fluid and consequently affecting the fluid film at the seal faces - above that pressure therefore an alternative is required and Plan 53B is the most widely used.

The only issue you have to be aware of when using a dual pressurised seal on a hot pump is the choice of barrier fluid - you don't want it flashing off as it passes the inboard faces.

 

[Airsporter1st]

P.S. Just re-read your post: With a 53B you will also need to think about cooling the seal loop. If water is not available, you can use finned tube or, if necessary, an air-blast cooler.

In case you are not aware, as a general rule the accumulator should be pre-charged with nitrogen to 0.9x the minimum barrier fluid pressure. So if for example your seal chamber was at, say, 10 barg, then your minimum barrier pressure would be 12 barg (to maintain a 2 bar differential across the inboard seal - varies depending on seal manufacturer)and thus your precharge pressure would need to be 0.9 x 12 = 10.8 barg.

Also one of the most common problems I have encountered with plan 53B is the lack of a precharging kit. Be sure to determine what is required from your accumulator vendor and be prepared to supply and fit a pressure regulator to your nitrogen bottle. I've lost count of the number of times I've been on site and they have had no precharge kit or, even if they have one - no way to connect to the nitrogen bottle regulator.

 

[Petercooper]

thanks for the input pumpsmart. will update thread for results

 

[gyaneshwarp]

I would like to recommend API Plan 53 C.
No need of Nitrogen pressurisation. Also no need to calculate the bladder prssure.
For variable suction pressre outboard seal is subjected to maximum pressure in running as well static condition. This may reduce seal life.

 

[CaracasEC]

I would like to recommend plan 23 + 53B. Plan 23 will work on the heat dissipation on the seal chamber (outside the seal faces) while plan 53B will work on the seal faces.

 

[gyaneshwarp]

I think Plan 53 C with Face to Face Seal will be best option.

In face to face seal, no need of any flushing plan to dissipate the heat of inboard seal.

Also seals become stationary seal to give advantage of stationary seal.

 

[Airsporter1st]

I would think very carefully about the use of Plan 53C on a bottoms pump. The sense line can readily block up and the dirty oil can also cause scoring of the cylinder, damage to the piston seals and/or prevent movement of the piston altogether.

In any of the above cases it then stops working.

Even filling the sense line with clean oil, which I have done in the past, only delays the inevitable.