Glycol Issue Closed loop 1

[MacMcMacmac]

Hello again. We just shut down for our annual maintenance an I was greeted with the following mess. Glycol was replaced in 2014 with GE Corrshield 4404. Unit is a Munters CargoCaire dehydration unit utilizing a Carrier chiller to remove heat from the system. Just wondering if anyone has dealt.with this before. I would have though this would ha e lasted a lot longer than this. The green color immediately raises concerns of copper corrosion. GE Power and Water was sold off and sold off again so trying to reach any engineering support is hopeless. Very concerned with coil plugging. Surge tank also has a thick layer at the bottom, but much thinner and diluted. The glycol was gin clear when we put it in.

 

[HVAC-Novice]

i couldn't find actual data on corr-shield you list. What is the actual glycol and is that the approved inhibitor?

There is supposed to be annual testing and replenishment of buffers etc. With proper maintenance, brand name glycol should have a life of 20 years.

system also should have de-aeration.

If you don't do or have what I listed, then problems you see are what you expect after 19 years. what I say is based on DOW glycol (and the appropriate one used for the application). If you use lesser quality, things are worse.

 

[Rputvin]

Corrshield is a molybdate-based inhibitor if memory serves. It works better in systems that are not de-aerated. Nitrite inhibitors require de-aeration.

You charged the system in 2014 and didn't look at the fluid for nearly a decade? Or is inspection of the fluid part of annual maintenance? What were the results last year? Or was any testing done beyond "looks good"? Does the concentration of glycol match the readings taken during initial fill and subsequent maintenance? Any other additives used, or was it just water, glycol, corrosion inhibitor? What cleaning procedure was used before the glycol charge was put in? Was city water used as the water half of the glycol charge, or was it from premix totes diluted with distilled water? Was deionized water used?

We ship over 100 closed loop systems per year, we see glycol failures every few years. Some are newly commissioned systems that have trouble out of the gate, some run for a few months or years before trouble arises, some we see at the end of life 10-20years into service. Incompatible chemistry, leaving cleaning products in place, overtemperature events, pH imbalance, chloride intrusion, bad fill water, unchecked corrosion, incorrect maintenance procedures like topping off with incompatible fluids, or my favorite common cause "yeah we had a guy checking on that, I guess I haven't seen him in a few years..."

Flush it, recharge it, and move forward with the right fluid. Send off samples for analysis to the new vendor if you want to open that can of worms, but if no one has been watching the numbers I'm not sure what an analysis will tell you at this point other than you've got corrosion and failed glycol.

 

[HVAC-Novice]

Yu will have to do really great cleaning of the entire system. imagine that sludge sitting in all the coils, valves.... didn't they ever check strainers? I'm surprised they even had sufficient flow/heat transfer.

 

[MacMcMacmac]

So, we've sent off the goop to be analyzed and will be getting the glycol itself analyzed as well.

Looking through the manuals of both CargoCaire units, the type of glycol is indicated, but there is no mention of ongoing analysis or changeout intervals. You don't know what you don't know, or aren't told.

The current chemical is Corrshield OR4404, which is an inhibited ethylene glycol. Before installing this, the system was flushed with a product called Ferroquest to clean out any iron deposits in the system. We got the full meal deal at the time, I'm sure. It was flushed after cleaning and the Corrshield was installed. I'm sure city water was used for the dilution. The water here in Ottawa is not very hard, but I guess distilled water would have been a better choice. Finding 6 205l drums of distilled water would have been a bit of a performance I'm sure.

This filter is installed within 3ft of the pump outlet and ties back into the inlet, so the pressure drop across it is always very high.

For now, we will await the analysis and perform a very aggressive filter monitoring and changeout procedure for the next few months.

The glycol in the second system has been in there since 2003, so I'm a bit worried about it now. It's still crystal clear in the tank sight glass.

 

[Rputvin]

City water brings more than just dissolved solids (hardness) - they treat it with all kinds of fluorides and chlorides as part of the sanitation process and preparation for drinking, depending on your local municipal setup and how the water is sourced and treated. Some city water is more prone to biologic growth, some is more prone to deposit minerals, some has pH values that are outside the ideal.

Your best bet is a local water treatment specialist who is well-versed in the local water chemistry as well as codes and regulations that determine acceptable chemical usage and discharge limitations for your site. Sign up for annual diagnostics at a minimum, and save the reports so you can track water chemistry over time. If you end up with another mess you'll at least be able to track down the timeline and better determine if there was a gradual shift over time, or a specific event that caused a shift. And you'll have someone to blame if the contract says they need to watch it, though I've seen varying levels of success trying to hold vendors accountable when something goes wrong with plant water.

There's nothing wrong with city water use, it just brings with it some unknowns and requires a little more monitoring and potentially extra additives to balance things out.

If you made it 9 years on a glycol system using city water for the fill with no real monitoring - you did pretty well. And if the end result was some goopy stuff you made it out alright. I've had customers lose equipment to corrosion or chemical erosion due to poor water conditions. One of the worst recently was a 304 stainless tank that wound up having high chloride content in the water from lack of maintenance and resulted in pinhole leaks, the fix included removing a wall in the building to get the old system out because of poor planning years prior.

 

[MacMcMacmac]

Ok. Sounds good. We have a very good Nalco rep who is well aware of the city water conditions. I'm sure he won't mind being able to increase the scope of his contract.

 

[HVAC-Novice]

Glycol usually is pre-mixed and a glycol system is NOT connected to domestic water. If you add domestic water, any leak you make up will dilute the glycol. A glycol system usually has a fill-station that has a tank with pre-blended glycol.
I'm not sure at what point of the distribution the blending happens (they don't want to truck water through the country). I suspect some distributor blends the glycol with tested water. The end user or contractor usually only gets to buy the mix and not 100% glycol.