Chiller Pumps - Leaking Seals
Chiller Pumps - Leaking Seals
(OP)
Hi,
I have a 120 Ton multistack chiller with two armstrong series 4382 25HP Pumps with 6" inlet and a 6" outlet that immediately gets reduced to a 4" header in the chiller. We have three of these chillers on-site and have found the seals leaking on all the primary pumps of each chiller. (secondary pumps are only for backup). We originally had to up-size the pump from a 15HP to a 25HP and we're getting about 430gpm. We've already replaced one seal on a pump and the new seal started leaking a few weeks down the road. The seals we have are spec'd for these pumps and are meant for systems with over 30% glycol. We have 35% in our system. We originally had a lot of air in the system that we thought could potentially heat up when cavitating in the pump and ruining the seals. We now have air separators on the chilled water system so it shouldn't be the problem.
Any ideas?
I have a 120 Ton multistack chiller with two armstrong series 4382 25HP Pumps with 6" inlet and a 6" outlet that immediately gets reduced to a 4" header in the chiller. We have three of these chillers on-site and have found the seals leaking on all the primary pumps of each chiller. (secondary pumps are only for backup). We originally had to up-size the pump from a 15HP to a 25HP and we're getting about 430gpm. We've already replaced one seal on a pump and the new seal started leaking a few weeks down the road. The seals we have are spec'd for these pumps and are meant for systems with over 30% glycol. We have 35% in our system. We originally had a lot of air in the system that we thought could potentially heat up when cavitating in the pump and ruining the seals. We now have air separators on the chilled water system so it shouldn't be the problem.
Any ideas?





RE: Chiller Pumps - Leaking Seals
Johnny Pellin
RE: Chiller Pumps - Leaking Seals
And feedback?
-Mike
RE: Chiller Pumps - Leaking Seals
An automated startup bypass around the chiller pump may help to reduce startup stresses as an alternate to VFD?
The seal may also be failing because of air lock up in the seal chamber ( the air sep may not be 100% efficient) - that could lead to loss of seal cooling. See if you can stop this air getting into the coolant circuit. On the other hand, the feed inlet and exit nozzle arrangement on the upstream coolant expansion drum may not be permitting the coolant to degas properly.
RE: Chiller Pumps - Leaking Seals
RE: Chiller Pumps - Leaking Seals
There are a number of things that could be leading to your seal dry running. Whats the elastomer material? How quickly does your speed ramp up? (i.e. 0 to 3600 rpm is 30 seconds) Is there a flush plan? any piping plan already with it? Does your process require you to vent on startup?