Brighton,

I have started anew thred, with your question as follows, quote:
Here is a new topic:

There are a set of duty/standby pumps which are controlled by the level bridles installed on the reboiler upstream of the pumps. Both pumps are 4 KW fitted with mechanical seals. For whatever reason they need to drain the level bridles twice a day and every time they do that, the duty pump shuts down and restarts in a few seconds afterwards when they put they close the drain on the bridle and put it into service. This is because the pumps are controlled by level in the bridles but actually the suction line to the pumps has got liquid in it...I noticed they have been doing this for 12 month! I talked to the Production Superintendent to put the Maintenance Override Switch (MOS) on the pump to avoid pump stop due to action of draining the bridles. There are two options I can think of:

1- Put the MOS on as discussed above
or
2- Keep on the pumps start and stops (twice daily) and if they are busted, buy new ones as they are not big pumps.
Unquote

I would not change ANYTHING soch as an MOS, UNLESS I did a proper HAZOP. While your solution will improve pump performance, there is some considerable hazard you may introduce with regard to the MOS being monitored and controlled properly. This may end up in a disaster, so it may be the story of the kingdom for a horse! The problem is relatively minor; any solution needs to be properly engineered and risks evaluated. Please dont rush into solution mode till you have a clear understanding of the problem and its ramifications.

Brighton, why do they need to drain the bridle & thus the reboiler? Isn't this part of boiler system operations?

Josh, the reason is the reboiler tends to process MEG (Mono Ethylene Glycol) but for reasons, MEG and Gas Condensate come together and in time condensate accumulate on top of MEG in the reboiler and fills the upper section of the bridles and it leads to false reboiler level reading in the control room.

Yea, that seems to be similar to draining a steam drum's level gauge when steam accumulates on top of water.