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Pump engineering design

Pump engineering design

Here´s my issue.
There is several pumps in the plant that have an API plan, to be exactly Plan 52+11.
The product to be pumped is gasoline 95 octanes, and in others is Diesel.
supposedly to cool the mechanical seal (eagle Burgmann). the pumps also have a cooling system (Fin Fan cooling system) to cool the water that takes from the plan 52 (that use a thermical Oil). In the upper part of the image "Plan 52" shows a venting, that acording to the image is normally open. What I want to know is the following.
If it is necessary the plan 52 to these products (gasoline) (Diesel). why?
If it is not what is the use of plan 52, please examples. For warranty the system need to be work on that way. The venting system. I have read that need a cylinder to provide pressure.
It is possible to leave the venting to the atmosphere, The valve open while the system is working. (why?. Additional data: Power of the pumps: 50HP, 75HP, 70Kw, 180HP. These go to the loading rack.
I also have a plan 53B in other pumps (To a tanker) the same questions. 200KW, 250KW.
these are air cooling. (Do not have the fin fan system).
In my experience I have never seen a system in these types of pumps handling gasoline or Diesel, that´s why my questions.

RE: Pump engineering design

An API Plan 52 system is defined as a non-pressurized dual seal with a barrier fluid tank vented to a suitable vapor recovery system (such as a flare). This plan is usually installed for environmental control of emissions to atmosphere. In our location, this would not typically be required for low temperature gasoline or distillate to a loading rack. A plan 52 is not designed to be pressurized and should not be pressurized without careful review of the design. The seal may not be suitable for reverse pressure. The cooling of the seal pot is often used to remove the heat generated by the seal faces and the pumping ring. Even in low temperature applications, such as yours, the seal pot may run quite hot.

I would not recommend leaving the vent on the plan 52 open to atmosphere. Doing so negates some of the benefit of a dual seal arrangement. Blocking in the vent would allow the barrier fluid to pressurize to seal chamber pressure over time which can also be detrimental to the reliability of the seal. Ideally, the vent would be open to a vapor recovery system such as a flare. If a vapor recovery system is not available, it can be operated with the vent blocked in. We do this in some of our offsite areas, but I would still not recommend it.

The plan 53B system is designed to be pressurized above seal chamber pressure and must be pressurized to work properly. This system does not require the vent to flare, but is generally more complicated. Some cooling is typically required.

For high octane gasoline or diesel fuel to a loading rack, we would normally use a single seal with an API Plan 11 flush. If a dual seal was required for some reason, we would use an unpressurized Plan 52 vented to a flare or other vapor recovery system. We would only use a Plan 53B in this service if no vapor recovery system was available and if we were required by environmental requirements to install a dual seal.

Johnny Pellin

RE: Pump engineering design

eagle Bergmann have some good info -

All the info says keep the vent open to atmosphere via an orifice but connect to a flare or similar.

The valve needs to be open as the seals are designed that way to have seal fluid at very low pressure.

Is it needed in gasoline or diesel service - no idea - you would need to question the process engineer or environmental requirements about fugitive leaks and seal leaks

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Pump engineering design

thanks for your replies. See the image for datails.
All these system is necessary. In others words the api plan 52 plus the fin fan heat exchanger system to cooling the water to convey gasoline or diesel to a loading rack.
A double seal arrangement is necessary for this. is a simple system. I don´t understang why so many things for the cooling. I think that API plan 11, it is enough.
Excuse me for my foolishness, but I did not understand something, let me see if I understood; you are saying that If a keep a block the venting valve is good because would allow the barrier fluid to pressurize to seal chamber of the seal. But if I let it so much time it can be detrimental to the reliability of the seal. So is.

Plan 53B need to be pressurize with Nitrogen (chamber of the api plan) how I can determine the pressure necessary for that.
and the last what is the difference between a plan 52 y 53A. I know that have a manually pump to refill the thermical Oil. But I don´t find the reason why.

The tank of gasoline and diesel are atmoshperic.
Thank you for your help. You deserve five stars.

RE: Pump engineering design

I would not have selected the cooling arrangement shown for these systems. For cold finished product, the heat generated by the seal faces is unlikely to be high enough to require such a complex cooling system. A plan 52 with no cooling and a Plan 11 on the primary seal would be much simpler and should be more than adequate. If additional cooling was required (consult with the seal manufacturer), then I would consider a Plan 23/52 as shown in the attached picture.

If the vent on the seal pot is closed on the Plan 52, the seal pot will pressurize to seal chamber pressure over time as the slight leakage across the inner seal has no path to escape. Once this pressure is equalized, there will be no differential pressure across the primary (inner) seal. This is generally considered to be bad for seal reliability. Mechanical seals should have some differential pressure.

A Plan 53B is normally pressurized to about 30 to 50 psi above the process pressure in the seal chamber. If the process pressure is highly variable, this can be difficult. We have also seen variation in the pressure of the 53B bladder system from day to night, rain to sun and with changes in ambient air temperature. The pressure needs to be set high enough to maintain at least 30 psi differential at all times. But, if the differential pressure is too high for the particular seal design, reliability may suffer.

A Plan 53B system is complex and expensive. It is only used if the process pressure is too high to allow for direct pressurization of the barrier fluid. Below about 80 psi, we would apply direct N2 pressure to the pot and not install the bladder system. A pressurized system (53 or 53B) is normally used for streams that are very toxic or environmentally damaging. For clean finished gasoline or diesel fuel, I would not normally consider a 53B. A 52 is more than enough protection against fugitive emissions or visible leaks. We have not had good results with 53B and I would use that plan only if I had no good alternative.

Johnny Pellin

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