Caterpillar 3512 Emergency Generators, Cat ELC coolant

[Jay]

We have a pair of 1,620kw (2,172 hp) Caterpillar 3512 emergency power generators at the telecom central office where I work. This is the most recent coolant analysis result for them. The coolant is Caterpillar ELC that was installed 6 years ago. Each generator has more than 800 gallons of coolant. The analysis was done by Butler Machinery with Level II kits purchased through Dyson Analysis. The first column is gen 1, the second gen 2.

code:

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    GEN #1              GEN #2
Total hrs: 117 hrs      118 hrs
Appearance: red/orange/clear  red/orange/clear
Odor : normal          normal
Foam : normal          normal
Oil/Fuel : none        none
Maintenance & additives:
Glycol 50%              32%
Freeze -37C            -17C
Boil 107C              103C
PH 8.7                  8.7
Conductivity 3940      4040
NO2 490                 170
NO3 0                     0
SiO3 3                    3 
moO4 866                423
PO4 3                     0 
Bo3 1                    11
Seb 1380                870
Toly 1560               870
K 5636                 3437
Corrosion & Hardness:
Fe 0                      0
Cu 0                      0
Al 0                      0
Pb 0                      0
Sn 0                      0 
Zn 0                      0
TH 3                     42
Ca 3                     11
Mg 0                     31
Metal Pitting :
SO4 0                     0
Glycat 0                  0
CO3 0                     0
CI 0                      0
NH3 no                   no
Solids : none          none

  

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Many thanks to Terry for his line-by-line analysis of the data. One generator suffered a boil-over accident soon after installation, and was topped off with water. That generator is in trouble now. Can you guess which one?

 

[Chris142]

How do you overheat 800 gallons of coolant?

 

[Terry]

I am amazed at the lack of comment and questioning here with this INDEPTH coolant analysis on a stationary diesel. Jay, thanks for sharing here. Terry

 

[bruce381]

Gen 2 has a higher amount of dilution with harder water than gen 1 but corrosion metals still are low why is it trouble? bruce

 

[Jay]

Chris, you overheat the coolant by mis-configuring the load bank to operate at maximum load, at the same time building load is applied, during an outage. The combination just boils the coolant right out. Bruce, I should say, "starting to get into trouble" and you win the gold star by identifying the problem generator.

 

[04SpecV]

So who decided it would be a good idea to just "top off with water" ?

 

[Jay]

The contractor that built our network had control of the building before it was turned over to the owners, and the accident happened on their watch. The contractor decided to top off with water and saddle the owners with a $5,000 repair.

 

[Megadeus]

Wow. That's a pretty retarded thing to do with such expensive equipment.

 

[Ken2]

There is no way that engine should have overheated unless something is wrong in the plumbing or the air flow for the cooling. It should carry 110% load without overheating...big diesels are always tested at 110% of rated load on the test stand before they are shipped to the customer. Medium sized engines like this one should bog down from overload before they overheat. Are the engines subject to freezing? If not, I wouldn't use a glycol coolant--just water and suitable corrosion inhibitors and SCA. Why didn't your company's maintenance folks test the coolant at least every six months? A routine something like that is their responsibility. Ken

 

[Jay]

Ken, thanks for your comments. We definitely had a boil-over with coolant loss, and the contractor in charge of the building topped off the Caterpillar ELC coolant with water. Our coolant analysis results have shown this for some time. We do coolant analysis yearly since the generators typically run about 30 hours yearly. This is the first time we've done a level II analysis, though. I made Terry aware that we don't have freezing temps here, but he didn't recommend going with corrosion inhibiters and water. Neither did our Cat dealer. Our Cat dealer concurred with Terry's recommendations. I'm still pressing our managers to get started with this repair--expensive as it is.

 

[ctdhombre]

Jay, I have some questions. The generators were installed 6 years ago. Did the boil-over on Gen. #2 happen during install and testing? What is the nature of the problem now that is need ing repair? Is the boil-over the cause of the problem needing repair? If so, why was the repair delayed for six years?

 

[Jay]

ctdhombre, the boil-over happened soon after installation and testing. A power outage occured out of hours and, due to a mis-configuration of the load bank, full building load and full load bank load were applied at once, which exceeded the maximum power rating. The engine ran until it overheated and shut down. The $5,000 "repair" that I mentioned is the cost of draining some of the coolant and topping off with ELC concentrate and some additives to bring the anti-corrosion additives up to normal levels. The repair has been delayed because of it's cost.

 

[Gary Allan]

Okay ...so there's no "damage" other then long term corrosive insult. That is, the overheat itself hasn't ecessively damaged to engine due to the system safety interlocks. So we're talking just the dilution factor. You've got to take out so many more gallons of the current coolant ..and add way too many drums to bring the concentration up to par. Tell them to buy xxx drums a month. Wait until enough are accumulated.

 

[Jay]

Gary, thanks for the suggestion. That might work. A good portion of the bill is labor and the cost of hauling the drained coolant away (it's hazardous waste), but I'll give that a try.

 

[ebaker]

Is "Seb" Sebacetic acid? Whats "Toly"?

 

[Mr. Boston]

quote:

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Originally posted by Jay: ctdhombre, the boil-over happened soon after installation and testing. A power outage occured out of hours and, due to a mis-configuration of the load bank, full building load and full load bank load were applied at once, which exceeded the maximum power rating. The engine ran until it overheated and shut down. The $5,000 "repair" that I mentioned is the cost of draining some of the coolant and topping off with ELC concentrate and some additives to bring the anti-corrosion additives up to normal levels. The repair has been delayed because of it's cost.

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That's one tough Genset! Usually with that kind of load the alternator will loose sync and your voltage will sag resulting in a major brown-out.

 

[Jay]

ebaker, Terry tells me "seb" is sebacate, and "toly" is tolytriazole. Mr. Boston, it is a tough genset.