Waterbath Vaporizers, Corrosion, and Antifreeze

October 24 2017,

Waterbath Vaporizers, Corrosion, and Antifreeze

Featuring Rick Gladding

Two waterbath vaporizers in use.

Time for a little refresher on Waterbath vaporizer antifreeze. Waterbath Vaporizers work in much the same way as a residential boiler. You take one medium (in this case Water / Antifreeze solution) heat it up and transfer the heat the liquid LP changing it to a vapor. However, if the antifreeze is not maintained and tested it wears out over time from the constant heat and cool cycles. I have seen antifreeze that ignored over time will turn black and muddy. This is not good for the unit and also an expensive proposition to change. Anyway back to the basics.

All Waterbath Vaporizers, regardless of who the manufacturer is, share some common things. For one they are an open system. Unlike a boiler, they do not need pressure in the waterbath so don't go looking for a pressure reducing valve to fill the unit. You will notice a tank mounted on top of the vaporizer with a sight glass so you can see the level. These units also have a circulating pump to keep the heat transfer fluid at an even temperature from top to bottom of the unit. This next item is very important. You should see a ground rod that is connected to the chassis of the vaporizer. Fail to provide this and you will be kissing the vaporizer goodbye sooner that the Bruins win the Stanley Cup again. Due to these units being connected to electricity you must ensure they are grounded and protected with di-electric unions or flange isolation kits.

Now let's talk about Antifreeze. You CAN NOT run to your local automotive supply house or box store for antifreeze for these units. I have heard of one waterbath that failed in my neck of the woods due to this. When this unit was installed it was initially filled with the correct Anti-freeze but over time as it evaporated they went to the box store and added RV anti-freeze... That was a $35,000.00 no-no and the heat exchanger rotted out within 7 years. Thankfully it was the end user doing this and not the gas company. Again it boils down to training and proper maintenance practices.

There is a multitude of anti-freeze products out in the marketplace for use. Most of these commercial products have corrosion inhibitors in them. However, if you plan on using a glycol/water mix remember you must add your own corrosion inhibitor. Plan on leaving behind 5-10 gallons of whatever you fill the unit with for topping it off as needed. One further thing you must be cautious about. If you fill the unit in question make sure the antifreeze you are putting in is compatible with the material the unit is constructed of. There is a new packaged boiler-vaporizer unit on the market that has an aluminum heat exchanger and you must use an anti-freeze that works with aluminum. Also, make sure the water you are adding is Distilled or Deionized water. There are way too many additives in regular tap water.

You must test the antifreeze PH and corrosion inhibitor. One manufacturer recommends testing immediately after installation, then after 2 months or 200 hours, whichever comes first, then every 6 months or 500 hours after that. Just remember that at some point the antifreeze will have to be completely drained and replaced. A waterbath vaporizer is happy with a PH between the 8-10 range. Make sure your test strips have a range at least 7-10. If your PH is above or below the 8-10 range you must make adjustments to the fluid. Depending on what brand of antifreeze you installed there will be adjustments that you can make. Please consult with the manufacturer of your specific antifreeze to find out how to adjust it. If all else fail’s there are companies out there that do nothing but deliver install, test and maintain antifreeze. I know of one located here in New England that specializes in this and I bet there are more companies out there.

Stay safe and practice good service techniques...

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Branch Manager Rick Gladding.